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tough one: overheating on the highway
#1719465
01/01/15 08:29 PM
01/01/15 08:29 PM
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Joined: Jan 2003
Posts: 1,381
Youngsville, NC
dem440c
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,381
Youngsville, NC
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I'm at a loss on this one and I need some new ideas. Been fighting this on my Ramcharger since the beginning. 1985 4wd with a 318/727.
Plain and simple, it won't control the water temp on the highway. It will idle at 160° until it runs out of gas, you could drive it from NY to LA as long as you never got on the interstate. But start pushing the speed to 65 and beyond and that temp needle will slowly climb and climb until you back it down to 55 again.
First of course you say this is classic symptom of a plugged up radiator. Second you think maybe there is an airflow problem. After that you start reaching for ideas. I'm well past all of that, well past the "replace everything" stage. I'll summarize with bullet points.
- new 3 core radiator (replaced twice)
- new hoses (lower has the spring in it to prevent collapse)
- thermostat (replaced twice)
- water pump
- all air baffles in place
- engine is clean, no dirt/grease blanket etc.
- coolant is perfect color, nice and clean, so no crud is circulating in it
- no water in oil, no oil in water, no exhaust gases in water, no leaks anywhere inside or out
- runs perfect
Basically I'm down to replacing the engine, but I refuse to believe there is anything wrong with this engine, I have to be missing a clue somewhere. I'm serious, you could idle forever in traffic on a 100° day and barely crack the thermostat open. You could drive around the world at 55 MPH. Oil pressure etc. is perfect. There is no way this engine needs to be replaced.
Any other ideas?
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719467
01/01/15 08:43 PM
01/01/15 08:43 PM
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Joined: May 2007
Posts: 952
Queens, N. Y.
FASTBACK340
super stock
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super stock
Joined: May 2007
Posts: 952
Queens, N. Y.
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When I lived out in Pa. I had wrecked my then-new car and needed a bang-around. I found a `75 Dart (this was in `94) that had only 32K on it. Nice clean 4 dr. 6 cyl, A/C, automatic Brown & tan. The original owner, she said "it's never been out of Lancaster County. Never run on the highway". First time I attempted to drive back to NY with it to visit family I had the SAME EXACT CONDITION and eventually replaced exactly the same parts, PLUS I reverse-flushed the cooling system. Still overheated. At that point I wrote it off as sediment in the block from the car sitting that was fused in there…. and it wasn't until recently that I ran across the same condition in a late model Infiniti when I was still doing that. Here's what I learned.
When I reached-out to the factory service hotline for repair incidents similar, and what the resolution was, I was told that once a block is scaled-up around the cylinders it will never transfer heat correctly back into the water jackets. I had to replace the short block in the FX-35 to fix the overheat problem. We threw a whole bunch of parts at it too going from diagnosis to guessing. Is this a vehicle you've owned for a while? Or is it a recent addition to the garage? Granted, the Infiniti was aluminum, but it sounds like your gakked-up around the cylinders…..
`68 Barracuda 340-S
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Re: tough one: overheating on the highway
[Re: dd340]
#1719471
01/01/15 08:53 PM
01/01/15 08:53 PM
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Joined: Feb 2005
Posts: 528
SW CO
HemiSportFury
mopar
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mopar
Joined: Feb 2005
Posts: 528
SW CO
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Have you tried running the heater full blast while it's over heating? Does that help cool it down or does it even blowing hot air? That can give you a hint at what the problem might be.
'64 Sport Fury, 528 Hemi, FiTech EFI, 4-speed, 4.10 Dana 60
'57 Belvedere 2dr sedan, current project in process
'19 Cherokee Trail Hawk Elite
'03 Ram 2500 CTD HO, 6-speed 214,000 miles and still going strong
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Re: tough one: overheating on the highway
[Re: HemiSportFury]
#1719472
01/01/15 09:13 PM
01/01/15 09:13 PM
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Joined: Jan 2003
Posts: 1,381
Youngsville, NC
dem440c
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,381
Youngsville, NC
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thanks for the replies, I'll try to address them all - stock clutch fan and shroud, replaced the fan clutch once (forgot that on my original list) - have tried several different carburetors (not because of this problem, just because I have other 318s and carburetors get swapped around during various adventures) and the problem is always unchanged. So things like air/fuel mixture aren't real logical unless every 318 carb I have has the same problem, also unlikely cuz they run the gamut from 60's Stromberg to 70's Carter to 80's Holley models. BTW I have also been all through the ignition system and settings, checked for vacuum leaks, etc. The truck runs absolutely perfect, no hiccups, issues, weirdness of any kind. Starts instantly, runs perfect. - it has always been this way. I bought the truck in a dilapidated state and restored it. So I don't know if it was going on before that. - I have verified the aftermarket gauge reading two ways- with a Snap On thermometer in the rad neck and also with an infrared temp meter. It's right. - basically, if you are driving around town or sitting in traffic it will barely hang out at the thermostat setting of 160°. If you start running down a two lane highway at 55-60 MPH it will climb a bit and stabilize around 180°. If you get on the interstate and run with traffic at 65-70 MPH it will slowly climb and climb and climb, I've let it get as high as 240° before I ran out of nerve and backed it down. If you take it down to 50-55 MPH it will come back down to normal. Again, jump out and shoot a few spots on the block with the infrared meter and it will be darn close to whatever the dash gauge says. I've driven Chrysler products with every type of malady and in various states of disrepair, I've never seen something like this that had no reason to complain and still does. A d@#n 318 like this should be able to go to the moon and back. Frustrated.
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719474
01/01/15 09:22 PM
01/01/15 09:22 PM
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Joined: Jan 2003
Posts: 15,311
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,311
Omaha Ne
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has the timing been checked, initial, mechanical, vacuum, and total ??? Restricted exhaust???? heat riser not opening all the way, cat plugged (if it's still there), Internal baffle in the muffler, or restricted in some other way Converter slipping (long shot) I am assuming if it has an a/c condenser that it is not plugged 
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Re: tough one: overheating on the highway
[Re: TJP]
#1719475
01/01/15 09:36 PM
01/01/15 09:36 PM
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Joined: Jun 2006
Posts: 5,161
CT
GTX MATT
master
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master
Joined: Jun 2006
Posts: 5,161
CT
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My guess: youre not running a vacuum advance and don't have enough timing.
What is the timing set at?
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719481
01/01/15 11:33 PM
01/01/15 11:33 PM
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Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,443
Indiana
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""have tried several different carburetors (not because of this problem, just because I have other 318s and carburetors get swapped around during various adventures) and the problem is always unchanged. So things like air/fuel mixture aren't real logical unless every 318 carb I have has the same problem, also unlikely cuz they run the gamut from 60's Stromberg to 70's Carter to 80's Holley models."" Back when the 318 carbs were designed and tuned from the factory, I would guess that there was a different type of fuel than what we use today. If you tried several different 318 carbs, I would assume that they would all give the same results. Todays fuel (E10) needs a richer A/F mixture than when these 318 carbs were designed. If the engine starts to warm up at 55-60mph, then gets even warmer above that speed, then I would at least try to richen up the jets to see if that helps out the temp at those speeds.  I have had to richen up my A/F mixture just over the last couple of years. I am assuming that this is due to change in the fuel at the pump over the last couple of years. I can't imagine trying to run a stock 318 carb on todays fuel without changing the carb setup.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719482
01/02/15 12:59 AM
01/02/15 12:59 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I love the toughies  . I gotta stick with the basics: not enough water flow or not enough airflow. I'd make sure there is adequate airflow thru the rad however way you choose to check that. I'd toss the stat for an hour test which wont hurt the eng it being gone for an hour. I'd double check that lower hose/spring & you could block the rods up so it's on the power circuit just to elim AF ratio/potential vac leak. You might pressure check the cooling system when hot to see if there is a minor pinhole leaking combustion into the coolant. Keep us posted! With it going up to 240 there has to be a severe coolant or airflow restriction showing up at higher RPM when the eng is producing the most heat & that is when the inadequacy shows up. I have the same vehicle ex it's 2wd. You wouldn't happen to have a shop manual or a wiring diagram for it would you? Gas gauge is non op
live every 24 hour block of time like it's your last day on earth
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Re: tough one: overheating on the highway
[Re: scatpacktom]
#1719485
01/02/15 03:10 AM
01/02/15 03:10 AM
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Joined: Jan 2003
Posts: 1,381
Youngsville, NC
dem440c
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,381
Youngsville, NC
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some of you guys asked some really good questions, although if you go back through my first two posts on this topic so far you'll see that I already posted the answer.
Interesting thought regarding pulley sizes... it's the stock pulleys, they don't look any different than any other set of Chrysler small block pulleys that I have... and I have literally dozens of engines and twice as many parts in boxes (I have my own little Mopar junkyard with about 50 vehicles along with whole engines and tons of random parts stashed away). Interesting thought though, even though they look ordinary I believe I will take a measurement to verify the diameter. Why not, I've done everything else.
See, it bothers me that this is going on. I've driven Chrysler v8's hundreds and hundreds of thousands of miles with a 3 speed automatic and factory cooling systems. Before I got my diesel, I towed cars through over a dozen states at full highway speed with my 440/727 truck. When we moved from St Louis to NC I drove a 67 NYer with a 440/727 back and forth three times at full highway speed. Just a couple of stories, point is they weren't stymied by today's fuel or less than perfect conditions or anything else. A gol-durned stock 318 with every blooming part on it replaced and every blooming tuning setting quadruple checked shouldn't even come close to having this problem. An 85 318 should continue to purr away after a direct nuclear strike. What the heck is going on here.
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719486
01/02/15 04:29 AM
01/02/15 04:29 AM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
master
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master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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I think the new or rebuilt water pumps are the problem the impellers are cheaper and the tolerances start to stack up. Let us know what you find, this problem gets asked often. Maybe a hi volume water pump will help.
Last edited by ademon; 01/02/15 04:30 AM.
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Re: tough one: overheating on the highway
[Re: dart1962_440]
#1719492
01/02/15 01:18 PM
01/02/15 01:18 PM
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Joined: Jan 2003
Posts: 1,381
Youngsville, NC
dem440c
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,381
Youngsville, NC
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just put -another- new water pump on it yesterday, that's what prompted me to post this. Rad cap has been changed twice. here's a pic for the guy wondering about a winch up front:  it's an A/C delete truck with nothing in front of the radiator. The fan is working great, holds a piece of paper against the rad just fine. And if you reach towards the carb or something while it is running you can feel the air rushing over the area from the fan. The idea about disconnecting the trans cooling lines is a good one.... I had thought of that a year ago and forgot about it. I was thinking the same thing, eliminate the possibility of the trans fluid heating up the coolant in the exchanger. I'll try that too, thanks for the reminder. I guess some of you are on to something with cleaning the inside of the block. I have been discounting that since the coolant stays so clean but if there is a LOT of gunk really impacted in there I suppose it is possible that it just stays put. Gonna suck removing the headers and the motor mounts to get to all the freeze plugs so I can get a pressure washer in there... running out of ideas I guess.
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Re: tough one: overheating on the highway
[Re: 65Fury440]
#1719495
01/02/15 03:44 PM
01/02/15 03:44 PM
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Joined: Aug 2005
Posts: 11,543
chicagoland,usa
buildanother
I Live Here
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I Live Here
Joined: Aug 2005
Posts: 11,543
chicagoland,usa
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After all of the ramchargers from that period I had, only thing left I could suggest, I believe you should have covered by now, is the common issue of the factory worm clamps on aux trans cooler, which is sandwiched between rad and a/c condensor, seeped oil over time and the dirt and dust would collect on cooler core and rad core, slowing down efficiency big time.  You could easily spot that issue after removing that big plastic seal thing.
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Re: tough one: overheating on the highway
[Re: GTX MATT]
#1719496
01/02/15 06:56 PM
01/02/15 06:56 PM
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Joined: Jan 2003
Posts: 15,311
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,311
Omaha Ne
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Quote:
What about the question about timing, what is the initial, total without vacuum, and total with vacuum advance? 
Item 1, see above.
Item 2, Do not overlook a restricted exhaust. make sure the heat riser is wide open, then disconnect everything from the head pipe back. Pretty simple and will eliminate it. 
Item 3, The pulley sizing is also a possibility if the truck has been messed with over the years.
Item 4, Possible but unlikely. you appear to have a borderline heat transfer situation. Disconnecting the trans will most likely improve it due to removing a heat source which is designed to be there. That may mislead you to believe the trans is the culprit when you are just chasing your tail.
Keep it simple and 1 step at a time. Try to repeat your testing as EXACLTY as possible.
I will add that I use a digital thermocouple meter with a probe into the system as close to the thermostat as possible. doing so Gives you an EXACT readout if how fast and when things are changing
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Re: tough one: overheating on the highway
[Re: TJP]
#1719497
01/02/15 07:40 PM
01/02/15 07:40 PM
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Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan
I Live Here
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I Live Here
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Posts: 10,847
Oakdale CT
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I had the same problem, turned out the fan was not spinning fast enough at highway speeds. Was fine at idle or low speed all day..
"I think its got a hemi"
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Re: tough one: overheating on the highway
[Re: gdonovan]
#1719498
01/02/15 08:35 PM
01/02/15 08:35 PM
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Joined: Jan 2003
Posts: 8,393
Highland, MI.
Sunroofcuda
master
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master
Joined: Jan 2003
Posts: 8,393
Highland, MI.
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Someone mentioned the exhaust & whether or not the truck has the catalytic converter still on or not? Make sure the exhaust is flowing freely - clogged or really restrictive will make the engine temp go way up if it's enough. It would make sense on the highway that higher prolonged RPM would need more exhaust flow.
Also, I used to have a '78 Dodge Super Coupe that always ran hot. Pulled the radiator & had it boiled & pressure tested & it was fine, reinstalled & same hot running condition. Changed coolant & flushed the system & still ran hot. One day, we decided to pull the engine & clean it up, repaint everything (car was for sale & we were bored), & replace all the freeze plugs while the engine was out. When we popped the first freeze plug out, that was our clue. Basically, MUD came out. We pulled them all & really hosed out the passages & a LOT of sediment came out! Installed new freeze plugs, painted everything, put it all back together & it never ran hot again. The crap inside the coolant passages was the culprit. Good luck.
No Man With A Good Car Needs To Be Justified
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719499
01/02/15 10:16 PM
01/02/15 10:16 PM
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Joined: Jan 2003
Posts: 43,522
Round Lake Beach, Illinoisy
Rhinodart
Rhinotruck
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Rhinotruck
Joined: Jan 2003
Posts: 43,522
Round Lake Beach, Illinoisy
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I had a 69 Dart slant six that would do the same thing. I actually used it to tow my Harley down from Illiniose to Daytona Beach for the 50th Bike Week and had to stop every 100 miles or so to let it cool down, it got worse of course because I was towing a single axle trailer.  I tried everything on the way down, then I got mad and got ready to throw the radiator cap across the highway!  I took a good look at it and the brass seal was cracked it three places!  I walked across the street to an auto parts store, bought a new cap, and never had another issue. Basically there was not enough pressure in the system to keep the coolant flowing. 
Last edited by Rhinodart; 01/02/15 10:18 PM.
The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.
JB Rhinehart, Realist
A-Body's RULE!
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Re: tough one: overheating on the highway
[Re: Rhinodart]
#1719500
01/02/15 10:53 PM
01/02/15 10:53 PM
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Joined: May 2006
Posts: 2,046
ky.
kenworth_goose
top fuel
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top fuel
Joined: May 2006
Posts: 2,046
ky.
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Quote:
I had a 69 Dart slant six that would do the same thing. I actually used it to tow my Harley down from Illiniose to Daytona Beach for the 50th Bike Week and had to stop every 100 miles or so to let it cool down, it got worse of course because I was towing a single axle trailer. I tried everything on the way down, then I got mad and got ready to throw the radiator cap across the highway! I took a good look at it and the brass seal was cracked it three places! I walked across the street to an auto parts store, bought a new cap, and never had another issue. Basically there was not enough pressure in the system to keep the coolant flowing.
Rhino, the coolant flowing wasn't the issue. Every pound of pressure increases the boiling point or temp at which it will boil. I can't remember exactly how much but that's what the cap does. And of course keep coolant in. LOL
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Re: tough one: overheating on the highway
[Re: kenworth_goose]
#1719501
01/03/15 12:13 AM
01/03/15 12:13 AM
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Joined: Nov 2013
Posts: 695
Southern Alberta
Uberpube
mopar
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mopar
Joined: Nov 2013
Posts: 695
Southern Alberta
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If it hasn't physically boiled over, I am going to call out the gauge. I have had 2 mid 80's dodges do this that had bad engine to chassis grounds. Half gauge at idle, but when I put load on the engine, the gauges would climb, but I wondered why they never boiled over..Replaced the sensor, same deal, put a set of booster cables between the block, the chassis, and the brake master cylinder and the battery neg, gauge never went over half. Replaced the main ground cable, cleaned all the rest of the factory ground points, fixed.
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Re: tough one: overheating on the highway
[Re: Uberpube]
#1719502
01/03/15 01:07 AM
01/03/15 01:07 AM
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Joined: Feb 2003
Posts: 4,793
Castlegar, BC, Canada
That AMC Guy
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master
Joined: Feb 2003
Posts: 4,793
Castlegar, BC, Canada
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Quote:
If it hasn't physically boiled over, I am going to call out the gauge. I have had 2 mid 80's dodges do this that had bad engine to chassis grounds. Half gauge at idle, but when I put load on the engine, the gauges would climb, but I wondered why they never boiled over....
I had this exact condition in my baby blue Hornet. Would idle all day and putt around town and barely break a sweat. The instant you got it out and held a steady 55, the gauge would climb and climb. Well, one day on my way to my weekend job, it was a cool day and the gauge continued to climb. I said to hell with it. If it blows, it blows. I got to work expecting the overflow to sound like a coffee maker or who knows what - but it should have shown SOME sign of overheating.
Nothing.
I had a V8 rad in it (two core, 26" wide) and a 160° stat in it. I decided to swap out the sender just to make sure I physically changed everything.
Now, with the big rad and the cool stat, the gauge barely moves. Now I've got to swap the six rad back in and put in a proper t-stat to see if it gets any hotter.
Bloody Mary, Full of Vodka, Blessed art thou among cocktails....
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Re: tough one: overheating on the highway
[Re: gdonovan]
#1719503
01/03/15 02:06 AM
01/03/15 02:06 AM
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Joined: Jan 2003
Posts: 10,538
Freeport IL USA
poorboy
I Live Here
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I Live Here
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Freeport IL USA
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I think the first place I would start, at this point, would be by popping out one of the rear most freeze plugs and seeing how much gunk is in the block. That might solve the whole issue. I've seen blocks so full of gunk I pulled a freeze plug and it was packed full of sediment, there wasn't even any sign of coolant having been there for a long time. That one even flushed clear before the freeze plug removal! If that isn't the problem, you need to look for something strange. It well may be a combination of little things adding up. You have swapped a lot of parts. Now its time to shift or relocate some of those parts and see what happens. Quote:
I had the same problem, turned out the fan was not spinning fast enough at highway speeds. Was fine at idle or low speed all day..
I've experienced this one before as well. A simple test is to pull the fan off and hit the interstate and see if it gets hot.
Is your temp gauge mechanical or electric? I've seen electrical gauges miss read when the charging system is in a high rate of charge. They work fine at lower rpm, but as the voltage increases with rpm, things go array. Like stated earlier, if its really overheating, there should be signs of it doing so, more then a gauge reading.
While your looking at your pulleys, check to be sure the groves are not worn. I've seen recently (these parts are all getting pretty old now) where the sides of the pulleys were worn off and the belts were actually running on the bottom of the pulley instead of on the sides like they were designed to run, The result was slipping belts as the engine rpm increased. At lower speeds everything was great.
The sides of the pulleys need to be "V" shaped, the ones causing an issue were more "U" shaped. Gene
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Re: tough one: overheating on the highway
[Re: smos001]
#1719507
01/03/15 11:41 AM
01/03/15 11:41 AM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
Might be leaning out as you press into the higher speeds. Does it miss at high cruise? faint lean miss? a lean miss also cause a slight hesitation as you press on the gas at a stop sign.
You may have to rejet the carb a little.
Vacuum leak?
Do not discount the 2 guys who suggested this. I third this suggestion.
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Re: tough one: overheating on the highway
[Re: FASTBACK340]
#1719513
01/04/15 12:26 PM
01/04/15 12:26 PM
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Joined: Jan 2003
Posts: 1,381
Youngsville, NC
dem440c
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,381
Youngsville, NC
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Quote:
I sure hope we find out what the cause is as the remedies are all over the map…. 
holy moly you aren't kidding... you guys have a LOT of great ideas. A lot of them I have tried already and I've been taking notes on some things to try that I haven't done yet.
- full length headers, 2-1/2" duals through Flowmasters exiting in front of the axle. I'm pretty confident there is no exhaust restriction.
- gonna try the idea to remove the fan and see what happens. Only problem there is I have to drive 25 minutes to get to a highway, guess I'll bring tools and see what happens.
- I haven't mapped the timing yet to see exactly what the distributor is doing as the RPMs increase, I can do that. It runs perfect so I haven't been thinking in that direction but it wouldn't hurt to see what it is doing.
- pulling freeze plugs is gonna be a sucky job but I agree that the symptoms would line up with that cause so it should be explored. Man, that is gonna take me a whole freakin' weekend to pull all that apart and then get new plugs back in... sigh
- changing the ignition module is easy, I have a box full of them. I'll try that just because it is quick and easy.
- someone mentioned air baffles, I have all the ones in place that cover the gap between the core support and the radiator. What else should be there?
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719514
01/04/15 12:44 PM
01/04/15 12:44 PM
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Joined: May 2007
Posts: 952
Queens, N. Y.
FASTBACK340
super stock
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super stock
Joined: May 2007
Posts: 952
Queens, N. Y.
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Might be easier to pull the water pump and use a bora-scope and peek in through the timing chain cover openings first. Freeze plugs are a chore on an educated guess.
`68 Barracuda 340-S
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Re: tough one: overheating on the highway
[Re: FASTBACK340]
#1719515
01/04/15 02:02 PM
01/04/15 02:02 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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that if you do not post the solution (when you find it) that there might be a cyberspace lynching  . Recently a member lost his life cuz he DELETED his thread  . On the timing, in your driveway just run it up to the same RPM you are at on the highway when it is getting hot & see what you get with your dialback or make some marks. 0.0632683" around the circumference is 1 degree on the dampener or can use the tab as a ruler. 2&1/4 (2.246") is 35.5 deg which should get you close to what you have tho the can will kick it higher above that
live every 24 hour block of time like it's your last day on earth
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719516
01/04/15 03:41 PM
01/04/15 03:41 PM
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Joined: Jan 2003
Posts: 3,575
The Netherlands
BigBlockMopar
master
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master
Joined: Jan 2003
Posts: 3,575
The Netherlands
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Quote:
- someone mentioned air baffles, I have all the ones in place that cover the gap between the core support and the radiator. What else should be there?
I don't know what came stock on your car as I don't have any experience with these models.
But if you're adventurous you could take a trip simply without the hood mounted and see if the issue remains.
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Re: tough one: overheating on the highway
[Re: RapidRobert]
#1719517
01/04/15 03:49 PM
01/04/15 03:49 PM
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Joined: Jan 2003
Posts: 727
Ottawa, ontario
dd340
super stock
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super stock
Joined: Jan 2003
Posts: 727
Ottawa, ontario
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Quote:
that if you do not post the solution (when you find it) that there might be a cyberspace lynching . Recently a member lost his life cuz he DELETED his thread . On the timing, in your driveway just run it up to the same RPM you are at on the highway when it is getting hot & see what you get with your dialback or make some marks. 0.0632683" around the circumference is 1 degree on the dampener or can use the tab as a ruler. 2&1/4 (2.246") is 35.5 deg which should get you close to what you have tho the can will kick it higher above that
This made me think of something, can you duplicate the overheating in 1st or 2nd gear if you hold it at the same rpm as you run at highway speeds? If the engine doesn't heat up in the lower gears this would seem to eliminate the water pump and pulley possibilities. I would be interested to know the results of that.
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Re: tough one: overheating on the highway
[Re: Rhinodart]
#1719519
01/04/15 04:40 PM
01/04/15 04:40 PM
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Joined: Jan 2003
Posts: 3,050
Bowling Green, KY
cudaboy
master
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master
Joined: Jan 2003
Posts: 3,050
Bowling Green, KY
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Quote:
I still have not read if you checked or replaced your cap...
Its in there. Changed twice.
Dennis
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Re: tough one: overheating on the highway
[Re: FASTBACK340]
#1719522
01/04/15 06:46 PM
01/04/15 06:46 PM
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Joined: Apr 2005
Posts: 4,916
new berlin wisconsin
Mr T2U
master
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master
Joined: Apr 2005
Posts: 4,916
new berlin wisconsin
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I am surprised no one mentioned weak fuel pump.
if it cuts out at higher rpm's it can make it run lean.
of course if it's lean at the top end it usually surges.
perception is 90% of reality
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719524
01/04/15 08:16 PM
01/04/15 08:16 PM
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Joined: Jan 2003
Posts: 15,311
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,311
Omaha Ne
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Quote:
Quote:
I sure hope we find out what the cause is as the remedies are all over the map….
holy moly you aren't kidding... you guys have a LOT of great ideas. A lot of them I have tried already and I've been taking notes on some things to try that I haven't done yet.
- full length headers, 2-1/2" duals through Flowmasters exiting in front of the axle. I'm pretty confident there is no exhaust restriction.
- gonna try the idea to remove the fan and see what happens. Only problem there is I have to drive 25 minutes to get to a highway, guess I'll bring tools and see what happens.
- I haven't mapped the timing yet to see exactly what the distributor is doing as the RPMs increase, I can do that. It runs perfect so I haven't been thinking in that direction but it wouldn't hurt to see what it is doing.
- pulling freeze plugs is gonna be a sucky job but I agree that the symptoms would line up with that cause so it should be explored. Man, that is gonna take me a whole freakin' weekend to pull all that apart and then get new plugs back in... sigh
- changing the ignition module is easy, I have a box full of them. I'll try that just because it is quick and easy.
- someone mentioned air baffles, I have all the ones in place that cover the gap between the core support and the radiator. What else should be there?
At this point I would
1. verify the timing
2. verify the pulley sizing
3. look at lean condition due to jetting or a vacuum leak.
4. pop a freeze plug
What intake / carb setup are you running ??
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Re: tough one: overheating on the highway
[Re: TJP]
#1719525
01/04/15 08:38 PM
01/04/15 08:38 PM
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Joined: Jan 2003
Posts: 1,381
Youngsville, NC
dem440c
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,381
Youngsville, NC
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intake and carb are factory 2 bbl... I think the carb on it now is the factory correct Holley for an '85. At different times I've had a variety of factory carbs on it from 60's, 70's, and 80's vintage. As I mentioned, I have lots of cars/trucks/parts and am always swapping stuff around. The highway hot issue has been exactly the same regardless of what carb was on it. I can't recall ever changing the fuel pump, all I will say to argue that point is that by the seat of the pants dyno it runs good.
Ya know, that's another idea, I could book some dyno time to experiment with it. It would give me some other data points about how it is running and the A/F conditions etc.
I hope I don't get an internet lynching, please be patient with me as this truck is mainly just our beach cruiser and occasional knock around town rig. Updates may not be fast and furious as it is just one of many projects demanding my limited wrenching time. I would like to be able to drive to the beach at full speed so I continue working on it here and there.
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Re: tough one: overheating on the highway
[Re: roe]
#1719528
01/05/15 12:35 AM
01/05/15 12:35 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Dan you're doin fine & the lynchings ain't from an OP being too slow to respond to inquiries/suggestions etc but instead are from deleting whole threads and not reporting back when a final solution is finally realized/hit upon. Yes it's gonna be a blast when you discover what it as (assuming the gauge is correct & I'm inclined to think it is since it creeps up) cuz sumpin for sure is makin it reach 240F
live every 24 hour block of time like it's your last day on earth
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719529
01/05/15 12:53 AM
01/05/15 12:53 AM
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Joined: Jan 2003
Posts: 8,393
Highland, MI.
Sunroofcuda
master
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master
Joined: Jan 2003
Posts: 8,393
Highland, MI.
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Quote:
Quote:
I sure hope we find out what the cause is as the remedies are all over the map….
holy moly you aren't kidding... you guys have a LOT of great ideas. A lot of them I have tried already and I've been taking notes on some things to try that I haven't done yet.
- full length headers, 2-1/2" duals through Flowmasters exiting in front of the axle. I'm pretty confident there is no exhaust restriction.
- gonna try the idea to remove the fan and see what happens. Only problem there is I have to drive 25 minutes to get to a highway, guess I'll bring tools and see what happens.
- I haven't mapped the timing yet to see exactly what the distributor is doing as the RPMs increase, I can do that. It runs perfect so I haven't been thinking in that direction but it wouldn't hurt to see what it is doing.
- pulling freeze plugs is gonna be a sucky job but I agree that the symptoms would line up with that cause so it should be explored. Man, that is gonna take me a whole freakin' weekend to pull all that apart and then get new plugs back in... sigh
- changing the ignition module is easy, I have a box full of them. I'll try that just because it is quick and easy.
- someone mentioned air baffles, I have all the ones in place that cover the gap between the core support and the radiator. What else should be there?
Pop out one EASILY ACCESSIBLE freeze plug & see if there is a bunch of mud in that area. If it's clear, then it's probably not that issue. When I started popping out all the freeze plugs on my Super Coupe, there was lots of sediment at each of them - simply put - the cooling passages were really restricted. Sounds like you do not have an exhaust issue (headers & Flowmasters). If one of the mufflers was defective & really blocked, you would have no upper RPM's so you could feel & probably hear that. Good luck. Yeah - we are all anxious to hear what the issue really is - this is a GOOD one!
No Man With A Good Car Needs To Be Justified
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Re: tough one: overheating on the highway
[Re: stumpy]
#1719531
01/05/15 12:02 PM
01/05/15 12:02 PM
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Joined: Jan 2003
Posts: 1,381
Youngsville, NC
dem440c
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,381
Youngsville, NC
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Quote:
What torque converter are you running?
factory I assume... I haven't been inside the engine or trans, that would be the only parts of the truck I haven't worked on yet. I did replace the transfer case but that's as close as I got to the T/C. There are major parts from 5 different parts trucks in this thing so far, eventually to be 6 when I do a Cummins conversion but that is not planned for another couple of years. In the meantime I'd like for the 318 to be fully functional.
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Re: tough one: overheating on the highway
[Re: dem440c]
#1719532
01/05/15 06:27 PM
01/05/15 06:27 PM
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Joined: Jan 2003
Posts: 15,311
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,311
Omaha Ne
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Quote:
intake and carb are factory 2 bbl... I think the carb on it now is the factory correct Holley for an '85
Ok a stock 2 barrel with headers and flow masters coupled with todays awesome fuel could point to a lean condition especially when leaning on it IE: highway speeds. Bear in mind they were lean from the factory 
I would map the timing, verify the pulley sizing and then check the AF ratio 
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Re: tough one: overheating on the highway
[Re: TJP]
#1719533
01/05/15 06:33 PM
01/05/15 06:33 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
Quote:
intake and carb are factory 2 bbl... I think the carb on it now is the factory correct Holley for an '85
Ok a stock 2 barrel with headers and flow masters coupled with todays awesome fuel could point to a lean condition especially when leaning on it IE: highway speeds. Bear in mind they were lean from the factory
I would map the timing, verify the pulley sizing and then check the AF ratio
I have installed at least 10 sets of headers for my self and friends over the years. Every time I jetted up the carb, you have to when you put on headers. That's called tuning your car, not just bolting on stuff.
Then add 10% ethanol and your lean as hell.
Can't believe the OP and most everyone else over looks that. 
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Re: tough one: overheating on the highway
[Re: Challenger 1]
#1719534
01/05/15 08:52 PM
01/05/15 08:52 PM
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Joined: Jan 2003
Posts: 1,381
Youngsville, NC
dem440c
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,381
Youngsville, NC
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Quote:
Quote:
Quote:
intake and carb are factory 2 bbl... I think the carb on it now is the factory correct Holley for an '85
Ok a stock 2 barrel with headers and flow masters coupled with todays awesome fuel could point to a lean condition especially when leaning on it IE: highway speeds. Bear in mind they were lean from the factory
I would map the timing, verify the pulley sizing and then check the AF ratio
I have installed at least 10 sets of headers for my self and friends over the years. Every time I jetted up the carb, you have to when you put on headers. That's called tuning your car, not just bolting on stuff.
Then add 10% ethanol and your lean as hell.
Can't believe the OP and most everyone else over looks that.
fair enough, you could be on to something there. I have it on my short list to book some dyno time and see what the data says. Never a bad idea anyhow to measure things on the dyno.
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Re: tough one: overheating on the highway
[Re: Challenger 1]
#1719537
01/06/15 04:23 PM
01/06/15 04:23 PM
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Joined: Aug 2005
Posts: 303
Staten Island, NY
RO23dave
enthusiast
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enthusiast
Joined: Aug 2005
Posts: 303
Staten Island, NY
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Been reading this post with interest, as i have been having overheating problems with my truck, pulling my trailer. On level streets or highways, no problem, soon as i hit a hill, as on PA turnpike going to Maple Grove, i can watch the temp climb rapidly. Got me thinking, and saturday nite, i started my truck, let it warm up and checked the flapper, inside the snorkle extension of the air cleaner. It was completely closed, wouldnt open up, so i flipped over the top lid. Air cleaner was new, and the truck stopped shaking and ran smoother. I wont know if this will cure my heating problem, until the spring, but, i was desperate. Everything that was mentioned here, i've done, radiator, hoses, waterpump, spring in lower hose, distributor, fan clutch, you name i've done it. I would think the motor would go super rich, with this problem, and computer is trying to compensate. Again, i won't know until spring. Dave ss/ea 1355
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Re: tough one: overheating on the highway
[Re: dan9]
#1719539
01/07/15 04:10 PM
01/07/15 04:10 PM
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Joined: Jun 2006
Posts: 5,161
CT
GTX MATT
master
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master
Joined: Jun 2006
Posts: 5,161
CT
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More air/fuel being burned = more heat from combustion
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
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Re: tough one: overheating on the highway
[Re: GTX MATT]
#1719540
01/11/15 06:39 PM
01/11/15 06:39 PM
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Joined: Jan 2008
Posts: 2,225
ILLINOIS
volaredon
top fuel
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top fuel
Joined: Jan 2008
Posts: 2,225
ILLINOIS
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the "several carbs" he has had on there would rule out that, I'd think.
No 2 carbs I would think were jetted identical. especially that many carbs taken over that many model years. IDK if he tweaked them out and made all the adjustments possible on each carb while it was on this engine, but unless they were all Holley 2 barrels that came off of '85 Dodge trucks, I would have thought that he would have seen something different in how hot it ran between the various carbs if this was the issue. I have installed headers on more than 1 vehicle myself over the years and have never had it cause a lean condition or an overheat; headers release alot more heat than manifolds, if anything I would think things would run cooler with them especially at highway speeds, that was why so many motorhome guys would go to headers to dissipate the heat better;
Having said that, I used to maintain a '73 Dodge Van for an older couple in town, they'd bought it used and had sat more than not, before they got it; back in like '95 the thing had like 32K miles (over 20 years old "then") One time I got a call for a water leak, the back freeze plug on the pass side was trickling water; I went to replace it and that remains the most gunked up motor I have seen to date; I could not believe all teh rust and scale in the water jackets; it was so bad as to actually help slow down the leak at the freeze plug. They always only drove it in town and it wouldn't overheat but did seem to run a little warmer than it should; good thing they had not taken it out on the road.
Having discovered that, I popped every freeze plug I could and flushed the $#!t out of that block. It made a huge difference. Trucks and vans have plenty of room to get at most of the freeze plugs.
You don't need to pull them all but at least the easiest ones on each side and run a garden hose in one so the water can run out the next freeze plug hole.
Also; something I have seen more than once is casting sand remaining in the jackets after many years even with multiple "typical" coolant flush jobs over the years, sand collects in the very bottoms of the jackets and coolant just flows over. I just pulled a '76 360 apart 2 weeks ago, and sent to the machine shop for hot tank and bore/hone. I popped the freeze plugs from that block on the stand, and found it to have ALOT of sand in the jackets; this engine came out of a wreck 20-some years ago and put in a barn with a tarp over it and basically forgotten about.
I found the 4.0 block on my Wrangler to have had the same issue when I pulled it out to replace the frame 5 years ago.
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Re: tough one: overheating on the highway
[Re: volaredon]
#1719541
01/12/15 02:39 AM
01/12/15 02:39 AM
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Joined: Feb 2003
Posts: 4,793
Castlegar, BC, Canada
That AMC Guy
master
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master
Joined: Feb 2003
Posts: 4,793
Castlegar, BC, Canada
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Any thoughts on a blown head gasket? Water in the oil isn't always a sign of a bad head gasket. They can pop between combustion chamber and water jacket too and if light enough, don't always use coolant under this condition either.
Bloody Mary, Full of Vodka, Blessed art thou among cocktails....
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