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engine runs hot #2696053
09/10/19 08:51 AM
09/10/19 08:51 AM
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Posts: 176
Ontario Canada
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Bennoel 10 Offline OP
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Bennoel 10  Offline OP
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Joined: Mar 2019
Posts: 176
Ontario Canada
where do I start as I thought everything was covered. So here I go.... rebuilt 340 (stock),new rad with new clutch fan and shroud, new water pump, new heater core everything new as this was a rotisserie restoration. however the engine temperature gets very high. I have put 1000 miles on the car and it always runs very hot. over 200 degrees with a 160 thermostat. I noticed that the lower rad hose was cold when the temp. gauge read hot. the upper rad hose along with the heater hoses were hot. this lead me to believe that there was no circulation of coolant. pulled the rad, water pump, thermostat. everything checked out fine. the only thing that I found was the block wasn't cleaned out properly. quite a bit of sludge. found this out as a result of one of the freeze plugs rotted through. (engine shop closed down) Now I am wondering if this is my problem as I have lost confidence in the engine build. could the head gaskets be the problem?? maybe upside down causing blockage?? Not looking foreword to pulling the engine out. Any suggestions, similar problems??? Thankyou Moparts forum members.

Bennoel

Re: engine runs hot [Re: Bennoel 10] #2696065
09/10/19 10:16 AM
09/10/19 10:16 AM
Joined: Mar 2003
Posts: 5,134
Las Vegas, NV
Tom_440 Offline
master
Tom_440  Offline
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Posts: 5,134
Las Vegas, NV
What do you mean "sludge?" If the motor sat for a long time with water in the jackets, there would be rust. You could flush a lot of that out while the engine is still in the car.

Have you run the engine with the radiator cap off and seen the coolant circulating? Or if you run the engine with the thermostat out, is the lower radiator hose still cold?

Re: engine runs hot [Re: Bennoel 10] #2696067
09/10/19 10:17 AM
09/10/19 10:17 AM
Joined: Apr 2003
Posts: 12,188
Looking for a way out of Middl...
IMGTX Offline
I Live Here
IMGTX  Offline
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Posts: 12,188
Looking for a way out of Middl...
A few tips

Run the engine with the radiator cap off from stone cold to warm enough to open the thermostat.

As it warms up, and throughout the testing look, for strings of bubbles in the radiator neck that may indicate a leaking head gasket or crack. These will be more obviously a pattern of bubbles and not just gurgling splashing.

When the thermostat opens coolant should flow and you will see turbulence in the radiator neck. If it doesn't flow you probably have a thermostat problem. One thing that may help is to drill a 1/8" hole in the thermostat to help water flow around it. Many thermostats already have this. It makes sure hot water gets to the thermostat to open it.

If it flows well give it a minute to start warming up the radiator. Run your hand along the radiator feel for cold spots. If you have them it's probably a clogged/defective radiator.

If it is flowing well and the radiator is warmed up evenly you may have an undersized radiator or low coolant flow from bad water pump or restricted passage.

Pull the thermostat completely and see if it still overheats and if the water flows. No water flow is a definite clog or pump problem. This sounds dumb but is the water flowing correctly. Some water pumps push water in from the bottom and out the top of the radiator the factory pushed in the top of the radiator and out the bottom. Doubtful you have a defective water pump with the impeller reversed but I have seen crazy crap.

If you feel you need to flush the debris out of the block I have done it by popping a couple freeze plugs out of the motor. Preferably two per side and as far apart as possible. I use a garden hose to flush the crap out. It often can be done without removing the engine but it is messy. Since it is a fresh restoration you may want to have a fresh paint job on the engine and want to keep it that way. If it is a small block they have plugs behind the flywheel

Re: engine runs hot [Re: Bennoel 10] #2696070
09/10/19 10:22 AM
09/10/19 10:22 AM
Joined: Jan 2003
Posts: 28,063
Irving, TX
feets Offline
Senior Management
feets  Offline
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Joined: Jan 2003
Posts: 28,063
Irving, TX
Your best shot at cleaning out the cooling system comes from draining the coolant, refilling with water and lots of dish washing soap. Put the cap back on the radiator and run the engine for 20 minutes or so. Drain the system and do it a second time if it was really nasty.

That radiator could be clogged. You need a temp gun to scan across the radiator and look for temp spikes.

Last edited by feets; 09/10/19 10:31 AM.

We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: engine runs hot [Re: feets] #2696091
09/10/19 11:08 AM
09/10/19 11:08 AM
Joined: Sep 2003
Posts: 19,239
north of coder
moparx Offline
"Butt Crack Bob"
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north of coder
my question is, if this engine was "rebuilt", why is there sludge in the coolant passages ?
makes me suspicious of the entire "rebuild" process.
what other shortcuts were taken ?
sounds pretty scary to me.
beer

Re: engine runs hot [Re: Bennoel 10] #2696104
09/10/19 11:53 AM
09/10/19 11:53 AM
Joined: Feb 2014
Posts: 1,695
central il.
S
second 70 Offline
top fuel
second 70  Offline
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Posts: 1,695
central il.
If the lower hose is cold it isn't circulating the coolant. It could be air locked or clogged. Take off cap run engine and keep a look in the radiator to see if the thermostat opens if it does check temp gauge and let it run with the cap off and see if the lower hose gets warm. If it doesn't something is probability clogged but if it does watch it and see if it overheats. If it doesn't put the cap on and watch gauge and check hose if it starts getting hot and the hose gets cooler it's air locked. I have seen them overheat because the overflow hose was clogged up and even found one where for whatever reason if you took the lid off the overflow tank it was fine but if you put the lid on it would stop the flow??? Drilled a hole in the overflow container and never had a problem again. Good luck. Mike

Re: engine runs hot [Re: second 70] #2696143
09/10/19 01:21 PM
09/10/19 01:21 PM
Joined: Aug 2005
Posts: 299
Hinckley, Ohio
KWF340 Offline
enthusiast
KWF340  Offline
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Joined: Aug 2005
Posts: 299
Hinckley, Ohio
I battled a cooling problem a while back. Flushed the system multiple times to no avail. Then I had the radiator rodded out and everything was fine for a day, but the problem quickly returned. Running out of ideas, I installed a Tefba cooling system filter, flushed the system again and cleaned the radiator and no problem since.

It turned out there was (for lack of a better term) crud in the system. It looked like dirt/rust particles that presumably were slowly breaking loose from walls of the coolant passages, lodging in the radiator and inhibiting coolant flow. The filter did trap a bunch of particles that I saved in a jar to keep a running tab of what was in there.

Last edited by KWF340; 09/11/19 02:38 PM.

1968 Charger R/T, 440 Auto, GG1;
1969 Super Bee, 383, 4-speed, T5;
1969.5 Road Runner, 440-6, 4-speed, 96;
1970 Duster 340, 4-speed, EV2;
1970 Charger R/T SE, 440 (496), Auto, EB3;
1970 Dart Swinger 340 (416), 4-speed, EV2;
1970 Corvette coupe, LS5, 4-speed, Daytona yellow;
2000 Corvette coupe, LS1, 6-speed, Twin Turbo, Torch red.
Re: engine runs hot [Re: Bennoel 10] #2696598
09/11/19 03:57 PM
09/11/19 03:57 PM
Joined: Feb 2011
Posts: 211
Halifax, VA.
M
moparjack44 Offline
enthusiast
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Halifax, VA.
Originally Posted by Bennoel 10
where do I start as I thought everything was covered. So here I go.... rebuilt 340 (stock),new rad with new clutch fan and shroud, new water pump, new heater core everything new as this was a rotisserie restoration. however the engine temperature gets very high. I have put 1000 miles on the car and it always runs very hot. over 200 degrees with a 160 thermostat. I noticed that the lower rad hose was cold when the temp. gauge read hot. the upper rad hose along with the heater hoses were hot. this lead me to believe that there was no circulation of coolant. pulled the rad, water pump, thermostat. everything checked out fine. the only thing that I found was the block wasn't cleaned out properly. quite a bit of sludge. found this out as a result of one of the freeze plugs rotted through. (engine shop closed down) Now I am wondering if this is my problem as I have lost confidence in the engine build. could the head gaskets be the problem?? maybe upside down causing blockage?? Not looking foreword to pulling the engine out. Any suggestions, similar problems??? Thankyou Moparts forum members.

Bennoel


Do you know "for sure" it is running hot, or does the gauge says it's running hot. Is it steaming, is it pukeing? I had a "heating" problem on my 1st Gen 392. After much checking, re checking, doing and re-doing. I installed an after market temp gauge. ZAP,,,,, gauge problem, not heating ptoblem.


K.I.S.S.
Re: engine runs hot [Re: moparjack44] #2696733
09/11/19 09:58 PM
09/11/19 09:58 PM
Joined: Jan 2003
Posts: 10,486
Freeport IL USA
poorboy Offline
I Live Here
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Freeport IL USA
First off, 200 degrees is not hot, modern stuff runs at 210-220 normally. Hot is 230.
2nd, The 160 on the thermostat is the point at which the stat opens, past the opening point, the thermostat does nothing else but stay open until the temp drops below the 160, at which point it would start to close.
3rd, Are you sure your gauge is accurate?
4th. I'd be pretty concerned if I had to replace the core plugs on a freshly rebuilt motor. Sounds like they skipped cleaning the motor. What else did they skip? Gene

Re: engine runs hot [Re: Bennoel 10] #2696735
09/11/19 10:05 PM
09/11/19 10:05 PM
Joined: Nov 2013
Posts: 676
Southern Alberta
Uberpube Offline
mopar
Uberpube  Offline
mopar

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Posts: 676
Southern Alberta
Wondering about gauge as well, bad engine grounds make the gauges read high on old chryco products.

Re: engine runs hot [Re: Uberpube] #2696892
09/12/19 01:30 PM
09/12/19 01:30 PM
Joined: Jan 2003
Posts: 1,496
Bradenton, Fl 34203
Kilroy was here Offline
pro stock
Kilroy was here  Offline
pro stock

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Posts: 1,496
Bradenton, Fl 34203
As others have said, and I agree with, take the thermostat out. Fill it with water and watch the water flow. There could be crud in the cooling passages, slowing the flow. And as others have mentioned make sure it's flowing the correct way.

Re: engine runs hot [Re: Kilroy was here] #2697277
09/13/19 06:32 PM
09/13/19 06:32 PM
Joined: Jan 2011
Posts: 15,713
Central Florida
larrymopar360 Offline
Stud Muffin
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Stud Muffin

Joined: Jan 2011
Posts: 15,713
Central Florida
As poorboy mentioned, you already had a rotted through freeze plug??? How soon and they weren't brass???

And as many already said, if you had a cold lower hose you definitely weren't getting circulation, so it isn't JUST the gauge, and you have to figure out the circulation issue. Start with the suggestion of running it with the cap loose and heat on high and see if you get circulation and burp any air out if you're lucky. But if you had a plug rot out already, something is going on inside the block.

Last edited by larrymopar360; 09/13/19 06:35 PM.

Facts are stubborn things.
Re: engine runs hot [Re: Bennoel 10] #2699753
09/22/19 09:57 AM
09/22/19 09:57 AM
Joined: Mar 2019
Posts: 176
Ontario Canada
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Bennoel 10 Offline OP
member
Bennoel 10  Offline OP
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Joined: Mar 2019
Posts: 176
Ontario Canada
update.....
first off I want to thank everyone for taking the time to share their knowledge and help.
So I removed the rad, water pump, p/s pump, alt and brackets. Next I popped out the leaking (weeping) frost plug on the pass side along with a plug at the very front of the block. Then I ran water from the garden hose and flushed out what I could. Quite a bit of sludge (debris, sludge, stuff that doesn't belong) came out. I then popped out a plug on the drivers side also at the front of the block. At this point I borrowed a scope and tried to get a visual look inside. I had a difficult time figuring out where I was as it looked like I was inside some underwater cave or something. I did see the inside of a plug or two. I generally was satisfied that 95% of the sludge was gone, At this point I aimed the probe upwards and to my dismay I saw what looked to be a blocked coolant passage. (could see the blue gasket) I believe it was the closest to the front of the engine. I then looked in the drivers side at the same places and saw identical images. I do believe that directly behind this passage was a similar passage that I could see a opening through to the head.(could see a hole in the blue gasket) So at this point I think aha there's the problem, no circulation as a result of this restriction. I wasn't prepared to pull the heads off yet. I have reinstalled the water pump, rad etc. No thermostat as recommended by most. Started up the engine and discovered that the lower rad hose eventually got hot and could see circulation of coolant in the top of the rad. (very happy at this point) So far after running the engine at fast idle for some time the temp gauge stayed in the safe zone.(directly straight up and in the middle). Haven't had a chance to take it out on the road for the real test. hopefully that will happen today. My questions now are should I run a thermostat and are those gaskets suppose to block these passages????? Thankyou to all and will update later

Bennoel

Re: engine runs hot [Re: Bennoel 10] #2699758
09/22/19 10:09 AM
09/22/19 10:09 AM
Joined: May 2019
Posts: 6,175
nowhere
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Sniper Offline
master
Sniper  Offline
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nowhere
Not all the holes are for water circulation, most of them are to get the sand out after the cast iron has cooled off.

Tell us what head gasket you are using, maker AND part number.

Circle the blocked holes int eh picture below.

[Linked Image]


Re: engine runs hot [Re: Tom_440] #2699760
09/22/19 10:14 AM
09/22/19 10:14 AM
Joined: Mar 2019
Posts: 176
Ontario Canada
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Bennoel 10 Offline OP
member
Bennoel 10  Offline OP
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Joined: Mar 2019
Posts: 176
Ontario Canada
Originally Posted by Tom_440
What do you mean "sludge?" If the motor sat for a long time with water in the jackets, there would be rust. You could flush a lot of that out while the engine is still in the car.

Have you run the engine with the radiator cap off and seen the coolant circulating? Or if you run the engine with the thermostat out, is the lower radiator hose still cold?




by sludge I mean sand, grainy type of sediment.
after running without stat saw circulation and lower hose gets hot

Re: engine runs hot [Re: moparx] #2699762
09/22/19 10:17 AM
09/22/19 10:17 AM
Joined: Mar 2019
Posts: 176
Ontario Canada
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Bennoel 10 Offline OP
member
Bennoel 10  Offline OP
member
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Joined: Mar 2019
Posts: 176
Ontario Canada
Originally Posted by moparx
my question is, if this engine was "rebuilt", why is there sludge in the coolant passages ?
makes me suspicious of the entire "rebuild" process.
what other shortcuts were taken ?
sounds pretty scary to me.
beer


unfortunately for me my exact thoughts as I had other issues already

Re: engine runs hot [Re: IMGTX] #2699767
09/22/19 10:24 AM
09/22/19 10:24 AM
Joined: Mar 2019
Posts: 176
Ontario Canada
B
Bennoel 10 Offline OP
member
Bennoel 10  Offline OP
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Joined: Mar 2019
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Ontario Canada
Originally Posted by IMGTX
A few tips

Run the engine with the radiator cap off from stone cold to warm enough to open the thermostat.

As it warms up, and throughout the testing look, for strings of bubbles in the radiator neck that may indicate a leaking head gasket or crack. These will be more obviously a pattern of bubbles and not just gurgling splashing.

When the thermostat opens coolant should flow and you will see turbulence in the radiator neck. If it doesn't flow you probably have a thermostat problem. One thing that may help is to drill a 1/8" hole in the thermostat to help water flow around it. Many thermostats already have this. It makes sure hot water gets to the thermostat to open it.

If it flows well give it a minute to start warming up the radiator. Run your hand along the radiator feel for cold spots. If you have them it's probably a clogged/defective radiator.

If it is flowing well and the radiator is warmed up evenly you may have an undersized radiator or low coolant flow from bad water pump or restricted passage.

Pull the thermostat completely and see if it still overheats and if the water flows. No water flow is a definite clog or pump problem. This sounds dumb but is the water flowing correctly. Some water pumps push water in from the bottom and out the top of the radiator the factory pushed in the top of the radiator and out the bottom. Doubtful you have a defective water pump with the impeller reversed but I have seen crazy crap.

If you feel you need to flush the debris out of the block I have done it by popping a couple freeze plugs out of the motor. Preferably two per side and as far apart as possible. I use a garden hose to flush the crap out. It often can be done without removing the engine but it is messy. Since it is a fresh restoration you may want to have a fresh paint job on the engine and want to keep it that way. If it is a small block they have plugs behind the flywheel


rad seemed to be fine as there was good flow out of the car
no stat I can now see flow with no bubbles
water pump also checked out fine with a visual check when removed
used a garden hose and flushed as recommended (don't think that was my issue) I think the stat wasn't opening

Re: engine runs hot [Re: Sniper] #2699769
09/22/19 10:30 AM
09/22/19 10:30 AM
Joined: Mar 2019
Posts: 176
Ontario Canada
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Bennoel 10 Offline OP
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Bennoel 10  Offline OP
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Joined: Mar 2019
Posts: 176
Ontario Canada
Originally Posted by Sniper
Not all the holes are for water circulation, most of them are to get the sand out after the cast iron has cooled off.

Tell us what head gasket you are using, maker AND part number.

Circle the blocked holes int eh picture below.

[Linked Image]



don't know the gasket manufacturer of gasket or part number as I intrusted the engine shop to build my engine (my mistake)
as for the circles …. not sure as I was using a scope and traveling unknown territory

Re: engine runs hot [Re: Bennoel 10] #2699771
09/22/19 10:30 AM
09/22/19 10:30 AM
Joined: Jan 2003
Posts: 13,544
md
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mopars4ever Offline
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md
I agree. i think the t stat was not functioning.

Re: engine runs hot [Re: KWF340] #2699774
09/22/19 10:35 AM
09/22/19 10:35 AM
Joined: Mar 2019
Posts: 176
Ontario Canada
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Bennoel 10 Offline OP
member
Bennoel 10  Offline OP
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Joined: Mar 2019
Posts: 176
Ontario Canada
Originally Posted by KWF340
I battled a cooling problem a while back. Flushed the system multiple times to no avail. Then I had the radiator rodded out and everything was fine for a day, but the problem quickly returned. Running out of ideas, I installed a Tefba cooling system filter, flushed the system again and cleaned the radiator and no problem since.

It turned out there was (for lack of a better term) crud in the system. It looked like dirt/rust particles that presumably were slowly breaking loose from walls of the coolant passages, lodging in the radiator and inhibiting coolant flow. The filter did trap a bunch of particles that I saved in a jar to keep a running tab of what was in there.


I believe I have the same crud, but mine seemed to stay in the engine block and rot the frost plugs out in a short time.(three or four seasons and only a thousand miles)

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