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Excessive Heat Under Hood
#2501495
05/28/18 10:24 PM
05/28/18 10:24 PM
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Joined: Feb 2015
Posts: 265
Philadelphia, PA
GTXKARL
OP
enthusiast
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OP
enthusiast
Joined: Feb 2015
Posts: 265
Philadelphia, PA
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Hi everyone. I have really excessive heat underneath the hood my of 1970 Plymouth GTX. People tell me its too hot, that you cannot even touch the dip stick. The factory gauge says 180 degrees to a 190. Its not boiling out. Any suggestions for why this would be happening? Thanks.
“Working on cars teaches you patience... and every curse word imaginable.”
1970 Plymouth GTX -- A true gentleman's coupe, but a serious muscle machine.
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Re: Excessive Heat Under Hood
[Re: GTXKARL]
#2501656
05/29/18 11:34 AM
05/29/18 11:34 AM
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Joined: Jun 2004
Posts: 3,372
St. Charles, MO
wingman
Uncreative Title
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Uncreative Title
Joined: Jun 2004
Posts: 3,372
St. Charles, MO
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Underhood heat and engine heat are not necessarily the same problem.
You could be running very normal 180 or 190 degree engine temp, but have high underhood temps. Different things can contribute--cowl seal, radiator support seals, do you run headers, fan shroud or no, ignition timing, etc.
1969 Dodge Coronet Super Bee 383 A4
1970 Plymouth Road Runner 440 FC7 (sold)
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Re: Excessive Heat Under Hood
[Re: GTXKARL]
#2501696
05/29/18 12:36 PM
05/29/18 12:36 PM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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Are you running stock manifolds or headers? Headers coated inside and out run a lot cooler on my stuff.
As mentioned, check your under hood seals AND let us know what your timing is at both initial and total. Also, curious what is your A/F readings at idle and cruise?
Reasonably priced laser temperature guns are readily available on-line.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Excessive Heat Under Hood
[Re: topside]
#2501889
05/29/18 05:57 PM
05/29/18 05:57 PM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
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Although it might sound "weird" it seems if it's fresh restoration, we have a tendency to overdo it in the paint and coatings dept underhood and on the engine and related components, so it seems in some cases it "feels" like it's running "excessively hot", even though a temp gauge/heat gun say otherwise, so some additional heat may be trapped underhood, or more components are generating/radiating, or absorbing heat than they normally would if they were in their raw/natural or flimsy factory finish, I've had customers of restored cars swear it's "superheating" to on the verge of "meltdown", yet a hand held heat gun says otherwise, I've even installed thermal-couples in radiators/water pumps/blocks on running engines to prove that water temps where "normal", along with probing with a heat gun all the underhood components...so if the OP has a freshly painted engine/engine compartment, and no actual sources of high temp can be found other than the "human feel" of excessive heat, give the freshly painted components some time to age... if this is the cause?, just something to take into consideration
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Re: Excessive Heat Under Hood
[Re: GTXKARL]
#2502216
05/30/18 01:35 PM
05/30/18 01:35 PM
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Joined: Nov 2006
Posts: 2,254
IL
furious70
top fuel
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top fuel
Joined: Nov 2006
Posts: 2,254
IL
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My heat gun will show temps a little above 200* in various areas of the engine even with the 180* tstat, parts get hot.
You should try commuting with twin turbos, I can feel the heat rolling out from under the car at a stop with my arm out the window!
70 Sport Fury
68 Charger
69 Coronet
72 RR
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Re: Excessive Heat Under Hood
[Re: GTXKARL]
#2502426
05/30/18 10:02 PM
05/30/18 10:02 PM
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Joined: Nov 2010
Posts: 3,696
jersey
Spaceman Spiff
master
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master
Joined: Nov 2010
Posts: 3,696
jersey
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if it try to open the hood on my car after a drive, i have to wear a glove, or i'll just about leave skin on the hood latch.
526 cubes of angry wedge, pushbutton shifted, 9 passenger killer!
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Re: Excessive Heat Under Hood
[Re: GTXKARL]
#2502427
05/30/18 10:05 PM
05/30/18 10:05 PM
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Joined: Jul 2011
Posts: 953
Chicago
PurpleBeeper
super stock
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super stock
Joined: Jul 2011
Posts: 953
Chicago
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I really like the heat gun idea. Wrapping headers (if not coated) helps a lot. As jbc426 mentioned, you can get excessive underhood heat if the engine is running to rich (fuel burning in exhaust) or if too lean (lean = hot)...... I think that part is right anyway.
70 Roadrunner convt. street car
440+6, NOS, 4-spd, SS springs
'96 Mustang GT convt. street car
'04 4.6 SOHC, NOS, auto, lowered
"Officer, that button is for short on-ramps"
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Re: Excessive Heat Under Hood
[Re: GTXKARL]
#2503043
06/01/18 08:26 AM
06/01/18 08:26 AM
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Joined: Aug 2003
Posts: 2,465
Answering the call of the wild
ThermoQuad
top fuel
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top fuel
Joined: Aug 2003
Posts: 2,465
Answering the call of the wild
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Install an analog temp gage near the carb. This is on a 440 - Barbecue temp gage from the home store - mounted it in the middle of the intake next to the coil. The problem being described is not normal. Tune up required. 60% distilled water 40% antifreeze and a bottle of coolant enhancer. Mopar thermostatic fan package
Last edited by Dilbert; 06/01/18 08:28 AM.
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Re: Excessive Heat Under Hood
[Re: GTXKARL]
#2503101
06/01/18 11:23 AM
06/01/18 11:23 AM
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Joined: Aug 2005
Posts: 1,383
Az
69hemibeep
pro stock
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pro stock
Joined: Aug 2005
Posts: 1,383
Az
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My steering wheel is to hot to touch this time of the year LOL. Lack of timing will heat the exhaust system up also.
1969 Hemi Roadrunner 2nd owner
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Re: Excessive Heat Under Hood
[Re: furious70]
#2503139
06/01/18 12:51 PM
06/01/18 12:51 PM
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Joined: Mar 2005
Posts: 11,269
Slantytown
DUFFMAN
Ask And Ye Shall Receive
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Ask And Ye Shall Receive
Joined: Mar 2005
Posts: 11,269
Slantytown
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My heat gun will show temps a little above 200* in various areas of the engine even with the 180* tstat, parts get hot.
The thermostat only sets the minimum operating temperature of the cooling system, the capacity of the radiator and the operation of cooling fans determines the maximum operating temperature.
No longer taking $h!t from anyone!
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Re: Excessive Heat Under Hood
[Re: DUFFMAN]
#2503292
06/01/18 06:49 PM
06/01/18 06:49 PM
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Joined: Nov 2006
Posts: 2,254
IL
furious70
top fuel
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top fuel
Joined: Nov 2006
Posts: 2,254
IL
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My heat gun will show temps a little above 200* in various areas of the engine even with the 180* tstat, parts get hot.
The thermostat only sets the minimum operating temperature of the cooling system, the capacity of the radiator and the operation of cooling fans determines the maximum operating temperature. Yes, I should have made it clearer that my post meant that underhood temps won't equal the tstat trigger point.
70 Sport Fury
68 Charger
69 Coronet
72 RR
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Re: Excessive Heat Under Hood
[Re: TC@HP2]
#2503475
06/02/18 07:59 AM
06/02/18 07:59 AM
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Joined: Aug 2003
Posts: 2,465
Answering the call of the wild
ThermoQuad
top fuel
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top fuel
Joined: Aug 2003
Posts: 2,465
Answering the call of the wild
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Try being just a bit analytical here...do you want to fix this or not? I am a retired technical support engineer for extremely complicated technology so troubleshooting old cooling system should not be difficult.
There is an excessive heat issue here. Put the mud away that you all throw at the wall. Do you want to fix this or wallow in mudslinging? I really think you all like slinging mud. Utilizing a the process of elimination we can resolve this issue. I have dealt with this heat issue myself very successfully i might add...on more than several cars.
Put an analog temp gage under the hood like in the picture.
The cooling system and tune up must be at a fundamental basic starting point! 60% water/40% antifreeze/bottle of wetting agent. Timing and fuel mixture set properly. Min 15 degree btdc on the timing.
We have no clue as to what water pump is on here or does this engine have a Chinese alum water pump housing restricting flow.
We really don't know a whole lot do we?
Is the lower hose collapsing under load?
Manifold heat control valve not opening?
Check the temp across the radiator core while running at temp.
Make a chart of the temps - this could be a plugged core issue.
What radiator cap? How old?
Rad core - last time it was re-cored?
Rad shroud?
Fan type?
Viscous fan package?
What are the temps after a heat soak?
Does the car start by itself after heat soak [just turn the key]
After fixing the tune up, correcting the coolant package do you still have an issue?
Disconnect the transmission lines from the radiator and connect them together. No the trans will not blow up - we need to eliminate the trans as a contributing factor. 195 degrees thermostat is required btw.
There may be a significant change here then again maybe not
If the car has power steering it is very possible the pump is adding a ton of heat.
Last edited by Dilbert; 06/02/18 08:09 AM.
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Re: Excessive Heat Under Hood
[Re: ThermoQuad]
#2503712
06/02/18 10:51 PM
06/02/18 10:51 PM
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Joined: Nov 2010
Posts: 3,696
jersey
Spaceman Spiff
master
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master
Joined: Nov 2010
Posts: 3,696
jersey
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Try being just a bit analytical here...do you want to fix this or not? I am a retired technical support engineer for extremely complicated technology so troubleshooting old cooling system should not be difficult.
There is an excessive heat issue here. Put the mud away that you all throw at the wall. Do you want to fix this or wallow in mudslinging? I really think you all like slinging mud. Utilizing a the process of elimination we can resolve this issue. I have dealt with this heat issue myself very successfully i might add...on more than several cars.
Put an analog temp gage under the hood like in the picture.
The cooling system and tune up must be at a fundamental basic starting point! 60% water/40% antifreeze/bottle of wetting agent. Timing and fuel mixture set properly. Min 15 degree btdc on the timing.
We have no clue as to what water pump is on here or does this engine have a Chinese alum water pump housing restricting flow.
We really don't know a whole lot do we?
Is the lower hose collapsing under load?
Manifold heat control valve not opening?
Check the temp across the radiator core while running at temp.
Make a chart of the temps - this could be a plugged core issue.
What radiator cap? How old?
Rad core - last time it was re-cored?
Rad shroud?
Fan type?
Viscous fan package?
What are the temps after a heat soak?
Does the car start by itself after heat soak [just turn the key]
After fixing the tune up, correcting the coolant package do you still have an issue?
Disconnect the transmission lines from the radiator and connect them together. No the trans will not blow up - we need to eliminate the trans as a contributing factor. 195 degrees thermostat is required btw.
There may be a significant change here then again maybe not
If the car has power steering it is very possible the pump is adding a ton of heat.
His COOLANT temperature is fine. UNDERHOOD temperature is what he’s asking about.
526 cubes of angry wedge, pushbutton shifted, 9 passenger killer!
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Re: Excessive Heat Under Hood
[Re: GTXKARL]
#2504418
06/04/18 04:23 PM
06/04/18 04:23 PM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
super stock
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super stock
Joined: Jul 2011
Posts: 817
Eugene, Oregon
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Make some basic sheet metal heat shields for your manifolds/headers.
Every single car and truck you could buy started running stamped sheetmetal heat shields several decades ago. They reflect radiant heat coming off the exhaust away from the rest of the compartment & down toward where air is flowing off the K frame and towards the floors. They work.
Before I made & installed mine, I couldn't even touch the underside of my air cleaner after driving the car. I just reuse the bottom left/right corner valve cover bolts to mount mine.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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