Thread: incredibly hot engine bay temps, need advice or suggestions 41 Willys 350, pics insid

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small front grill area also and then the grill bars restrict about half of that--------------Whole truck as an aero object--little air flow into the engine bay where the carb/engine burns up a lot of that, then using air for the rear that is already super heated from the engine /exhaust-------then trying to pull air thru that rear rad with those two little fans(do you know the amps for them?????) that aren't mounted so as to shroud the whole core area--------

Plus probably an A/C evaporator in front of the front rad??????

Common problem with fat fendered cars. Correct timing port might help a little, and Jet Hot (or similar) coating on the headers will help some but as 34-40 and others have mentioned you have got to get some ventilation under the hood!!! Can't get much air in there and then it has no place to exit the hot air! Louvers on the inner panels will help a lot, along with some sore of air pickup under the car at the front to get some air coming into the underhood area....

Originally Posted by jerry clayton

small front grill area also and then the grill bars restrict about half of that--------------Whole truck as an aero object--little air flow into the engine bay where the carb/engine burns up a lot of that, then using air for the rear that is already super heated from the engine /exhaust-------then trying to pull air thru that rear rad with those two little fans(do you know the amps for them?????) that aren't mounted so as to shroud the whole core area--------

Plus probably an A/C evaporator in front of the front rad??????

I see what your saying about the rear radiator fans not really covering the whole radiator, I should try and find or make a shroud for the rear radiator. The coolant temps arent horrible and over the summer they were manageable, I think most of my problem is in the engine bay with not venting the heat out however. I do have an A/C evap in the front as well yes, im going to have to come up with something to get air in and out of that engine bay.

Originally Posted by rspears

You say which seems to say that it may not be different than it was before the carb change, but that you're noticing the operating temperature more now that you've got it running better?

Mike's right, some actual measured temperature data would help, but I think your problem is that tonneau. We can't see the details of the louver/vent cover, but from the picture it appears to have very small openings compared to the area. Without calculating the effective free area of your louver I'd bet that you're getting about 25% of the rated free air flow (CFM) of your fans, and maybe much less than that. In effect, it looks to me like you're bottling up the air beneath the tonneau cover, stifling air flow. The first thing I'd try is removing that black panel (if you can) and see what effect that has on your problem. If that solves it then your task is to come up with a louvered panel that has sufficient free area to move the volume of air your fans put out, with as little restriction as possible but still maintaining a "look" that you find acceptable, like maybe a sheet of aluminum or steel with rows of punched louvers. When you look at the rated flow of your fans and the necessary free area, you may find that you need to make that panel larger. Whatever you do don't add pusher fans to the pullers, or you'll further restrict the air flow even more.

I havent done any kind of testing really as far as temps there, however i am looking to do something to promote some air flow into that engine bay for sure. AS far as the fans in the back im going to look into a shroud of some sort, they kick out some serious air.

Do you think something like this hid along the inside of the inner fenderwells pointing down towards the exhaust and forcing the air to exit would be a plausible idea?
http://www.summitracing.com/search/p...rd=air%20ducts

nope, not enough pickup area. Louvers are about the only thing that will allow sufficient air flow to do any good.

Yea im going to continue looking, I have a good idea of what I want to do I just need to find it. Im sure I can find or make a sheet metal duct that would bend slightly to vent air from under the truck up into the engine bay. Secondly at the hood hinge I can possibly space it somewhat and be able to vent it out up there. Im also going to get some underhood temps to see if what im doing is going to work.

Underhood temps are driven by your engine temperature, and while the air flow out of the engine compartment will affect the outcome it appears from what you say that most of your cooling is done in the rear radiator. Like Dave Severson says, punching louvers in your splash panels is about the only way to provide the air outlet you're looking for.

What coolant temps are we talking about here, and what thermostat are you running? Is your second radiator plumbed such that the thermostat controls the flow in that cooling loop, too, i.e. do you have the radiators running in series with no air trapped in the rear unit? Do you have an electric water pump, or are you trying to flow through that extra system volume with an engine driven OEM style pump?

Well my coolant temps have remained reasonable so far, but it is currently pretty cool out so its going to be hard to say what its going to do in the summer. My biggest thing is the underhood engine temps, the thing really hasnt overheated on me except for when the relay went out for the rear fans.

I had it out in some 100 degree temps with the ac on over the summer and it stayed around 200 (that was with a large carb and a rich mixture), the stat is a 160. My concern is driven by the hot underhood temps and the leaner burn im getting from a more efficient carb. I just really want to get that underhood temp down, im going to have to take some before hand temp readings.

I found some nice little fenderwell vents that im going to cut in around where the headers are, they look as if they will blend well too. Secondly ive come up with a design to promote some air flow from under the truck into the engine bay. Thirdly im going to space the hood near the windshield an inch to help vent the heat out there. Fourth im going to build a shroud make a better shroud for around the fan that is in the engine bay. Then we shall see what happens from there.

I could run hoodless too that would take care of it all.

Here is a source for round vents that you can put into the fender skirts with a hole saw;
Dive-N-Dog: Dive-N-Dog Vent-R-5 Stainless Steel 5 Inch Boat Engine Vent Cover

Just one question and I may have missed this Your radiator is in the rear area with a fan or fans> You have an A/C Evap in the front grill I assume.. Why can't you put a fan In the grill to pull air into the engine bay.

Originally Posted by cffisher

Just one question and I may have missed this Your radiator is in the rear area with a fan or fans> You have an A/C Evap in the front grill I assume.. Why can't you put a fan In the grill to pull air into the engine bay.

Yea I do have one on the front behind the grille so that helps too

Originally Posted by 36 sedan

Here is a source for round vents that you can put into the fender skirts with a hole saw;
Dive-N-Dog: Dive-N-Dog Vent-R-5 Stainless Steel 5 Inch Boat Engine Vent Cover

Yea there's a few I found that are even bigger than this yet that I'll probably be putting in.

Could always add louvers to the hood also...

If you're running a 160 t-stat and your coolant temps are pushing 200F cruising on a 100F day that points to an air flow problem. Shrouds are a must have, because without them you can just be blowing the same hot air through the radiator in a re-circulation pattern, but giving the fan discharge a free flow path is critical. If your cooling system is doing it's job the underhood temps will take care of themselves - you're not going to pick up much heat due to the air surrounding the engine if your coolant is circulating right, your radiators are sized right and clean, and your airflow is unrestricted. I still say your problem is bottled up air beneath the tonneau, and the easy test is to run without it to see if the engine stays nearer to the t-stat control point.