VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 32 Chevy Engine runs hot

My 32 Chevy original 6 cylinder Engine runs hot, engine water temp is good, but engine is giving off a lot of heat, can feel it through the firewall. Even with open hood loovers. Is this normal for a 32 Chevy?

Yup, heat through the firewall is normal. Is a blessing in the winter and not in Summer.

These vintage cars are definitely hot inside of the cab in the summer and fairly cold inside of the cab in the winter.

Do you still have the firewall mat installed and the engine pans? Its my opinion that the heat is reduced when the engine pans are off. It allows the air to flow past the engine and under the body rather than being directed at the firewall. The downfall is it also allows a lot of road debris in. Not fun when touring dirt roads in rainy weather.

The firewall mat does reduce not only the heat from the engine but also noise. Removing the engine pans reduces the heat removed from the engine which in my opinion is more important than a bit cooler passenger compartment.

Thanks gentlemen, appreciate the info!!

I'm a bit puzzled by this suggestion that it is better to leave side pans on. I would think the more air getting into the engine compartment the better for cooling, that's what the louvers/vents to as well. So removing the side pans should significantly improve air circulation around motor improving heat dissipation as heat has a much larger area to escape, especially at speed when the warm air will be drawn out by suction. The heat that gets transferred into the cabin is largely due to the hot air surrounding the engine, not from direct contact with the hot engine itself, and also heat from exhaust pipe. I'm sure a VCCA member who is familiar with thermodynamics can give up the exact calculation.

It does not take a degree in Thermodynamics to understand why leaving the pans in place helps to cool the engine. The cooling has to do with the path that the air takes. First one needs to understand that virtually all the cooling air enters past the radiator core. Air will take the path of least resistance. In the case that the engine pans are removed the major path is through the radiator, then drops down toward the bottom of the engine and underneath the passenger compartment floor. It basically bypasses the rear of the engine. When the pans are in place the majority of the air again passes through the radiator but is forced to flow past the engine block before being directed down by the toe board. Yes a little air also exits out the hood louvers or doors (if they are open). The air therefore helps cool the exhaust manifold, rear of the block and head. Since approximately 1/3 of the energy in the gasoline goes to power the vehicle, 1/3 is removed by the radiator and cooling system and the remaining 1/3 is removed by the exhaust system and directly to air passing by the engine, that air flow is important to cooling the rear of the engine.

Now if you want a dissertation on thermodynamics, air flow models, pressure gradients, laminar and turbulent flow I could do that too. Just not worth the effort in MHO.

Chipper, while you give a very good explanation of how the air moves about in the normal engine compartment, the question was whether the removal of the sidepans would result in there being less heat showing up in the cabin.

I would expect if the hood was removed entirely for example, as well as the sidepans, the engine compartment area would run close to the temperature of the outdoors, and the engine itself would run perhaps a bit cooler than normal (and maybe not uniformly same temp). Since heat entering the cabin comes largely from the hot air in the engine compartment (and as it flows under the toeboard), no hood or sidepans would significantly reduce cabin heat I would expect. So any change in the airflow characteristics in the engine bay that results in more air entering the space (swirling in from sides of radiator rather than just through it) and having a ready source of escape (down sides as well as under toeboard) would reduce heat in engine bay and as a result reduce heat getting to cabin. Most hotrods have hoods removed, a big advantage of which is eliminating the over heating/cooling problem in a small engine bay.

I am not trying to challenge any conventional wisdom here, just trying to think of how the sidepans removal may serve to help cool the cabin. Of course the best means of determining this is to simply remove the pans and go for a drive.

Obviously you didn't understand my earlier post. Guess I may need to be a bit more thorough in my posts.

In that vein, a course in fluid dynamics might help better understand the flow of liquids and gasses (yes gasses are fluids). From Wikipedia "In physics, fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow…the natural science of fluids (liquids and gases) in motion." In case you didn't know that gasses are fluids.

Could you explain that to my 32 which runs cooler (engine temp) without the engine pans as apparently it can not read. Do you have any actual Chevrolet test or technical data to validate your eloquently stated post. Like Gunsmoke I do not want to be confrontational, however I am seriously considering removing the engine pans to help the cooling on my 32.

I spent many years in coolant research and development with a major coolant suppler. That included testing with instrumented engines under controlled and uncontrolled conditions. Also worked with all major automotive and heavy duty engine companies. That included several GM divisions as well as the tech center. I try to educate people on engine cooling and what factors are involved. That includes the inaccuracy of using only temperature gauge readings as an indicator of engine temperature.

Sorry that I have some how irritated you and your '32. You can choose to believe what you want and do what you want with your '32. Hope it helps.

No not irritated as life is too short for that. I do have a heat gun (and use it) so the gauge reading is not a problem. My car ran cool for several years without the pans and hotter after. The first time it overheated (after seven years of cool running) I found the water pump packing a little loose and adjusted. Also retorqued the head bolts and found a few seemed not tight enough. Installed a FS sealed pump and FS four blade fan (which was the same as I already had). The radiator was recored with a FS core when restoration was done in 2001. The block was boiled (hot tanked) when rebuilt. Due to a machine shop error it was rebuilt a second time five years later and cleaned again. The timing etc. is as suggested on this site and the car runs fine, but does heat on long uphills or when idling in traffic. Irritated? No! Frustrated? Yes! So I sure would like to cure this problem. My next attempts will be to remove the thermostat (160 which checks ok), remove the engine pans and replace all the head bolts. I do appreciate any and all ideas and thank you for sharing your expertise.

The engine has never been rebuilt on my all original '32. The original honeycomb radiator has not been cleaned and the core has several small leaks. The engine underpans are still in place and the water pump has not been rebuilt (it leaks a little around the shaft). There is no thermostat in the car either. At operating temperature the car runs in the "Alcohol Boils" zone. Since the car had sat in a barn for years and with the gunk that is probably in the cooling passages of the cylinder head, one would think that the car should tend to run hot.....but it doesn't.

I will try the stat removal first. When first restored without a thermostat the gauge hardly moved off the cold mark. Now with a 160 I can drive at 45-50 mph all day and it will stay in the "alcohol boils" range unless I pull a long or steep hill-one or two miles of 6-8% grade.

You might try adding a modern transmission cooler (a small radiator) plumbed into an oil line to help cool off the oil. I did this on my '27 truck and it helps keep the engine temp down.

Cheers, Dean

I agree that might help, but seeing it ran cool for a number of years I am sure there is a logical reason why it now tends to run hotter. Would rather find that reason than pile on the add-ons, but I do appreciate the information.

Chipper, I understand what you are saying, I can't tell if the engine pans are on or off because I don't even know what they look like, (sorry new at this, that's why I joined... to learn these things), also not sure what the proper firewall mat looks like, there is a vynal mat there but it's very thin, it has a few leaks and the heat is coming thru. Never the less, based on what I read from all those who posted is that they normally run hot, that doesn't sound unusual for a 32, and the water temp stays about normal regardless of how hot the engine is, so it appears the radiator is functioning properly. I'll have to more research to determine if the pans are on, and try to find out what the proper firewall mat looks like to determine if I have that or not.

I appreciate everyones input!!

Bobby

Raise the hood. Look down between the engine and the frame rail. If you can see the ground your engine pans are missing. If you can't see the ground then your engine pans are in place.

I had problems with my engine running hot before I installed the splash pans.I also got the new water pump from FS.Took out the rad.and backflushed it.Lots of goop came out.I threw away the thermosat and run Peak coolant with anti foaming additives and a water pump lubericant.Now my car runs in the (Normal) range all day long.Even after I stop the motor and come back and fire it up its normal.No more overflow from the cap.The passenger compartment is warm but not unbearable.As a matter of fact I don't even notice the heat.I believe the pans helped along with everything else.Its hotter outside than in my car.(I live in Florida).

OK, confirmed the engine pans are off, and as I say, still runs pretty hot in the cab, water temp stays around low side of alcohol boils zone. If there is a thermostat, shall I remove it? It will never be driven in the cold.

It sounds as though your engine is running as it should and I would not change anything. There are seals around the pedals, steering column, etc. Perhaps with a helper while going down the road and with a heat gun you could determine where most of the heat is coming thru. With an open vent and if a closed car and the windshield raised there is good ventilation, but it is not A/C . There are heat reflecting products that can be added to help if you are not concerned with showing or point deductions.

You did not confirm if you have the correct firewall mat to insulate the cab from the heat of the engine. The firewall mat is a heavy rubber with a thick jute backing and it covers the complete instrument panel side of the firewall.

OK,it doesn't appear to be heavy rubber, I'm guessing its not the original or proper mat. So now I have to figure out where I can I get one. Any suggestions?

www.quietride.com 209-942-4777 They are in Stockton Ca.