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
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OP
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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
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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
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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
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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: 15,565 Omaha Ne
TJP
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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
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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: 8,414 Highland, MI.
Sunroofcuda
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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: 43,650 Round Lake Beach, Illinoisy
Rhinodart
Rhinotruck
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Rhinotruck
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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.
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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
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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: 728 Southern Alberta
Uberpube
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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: 4,815 Castlegar, BC, Canada
That AMC Guy
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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: 10,668 Freeport IL USA
poorboy
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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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