When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hey everyone new to the site and new to owning a C3.
Now the issue. I am having over heating problem. To start with I will tell you what's done. I turned the motor into a 383 stroker with headers. I have put a new water pump, thermostat and 3 row single pass aluminum radiator with duel electric fans. I am also using water wetter but I am still overheating. It did over heat befor I did all of this back when I first bought it. I just couldn't pass up 2k for a running and driving c3 numbers matching. My question is what to try next. Tempeture wise when I used a laser to check it was 255. Any advise would be great
Just to clarify, you checked the upper radiator hose while the car was running and warmed up, and you got 255 degrees F?
The stock L82 electric fan switch doesn't come on until 235 degrees. Did you use a lower temp switch to control your dual fans, with relays, and are they operating?
What is your timing set to?
Did you drill a tiny hole in your thermostat to ensure there isn't a trapped air bubble stalling your water pump and/or keeping your thermostat closed?
What water pump did you use, the specific one for a Corvette?
Are you sure the thermostat is opening?
Is the spring still in the lower radiator hose (you can feel it if you squeeze it, don't burn your hand)?
Is it overheating while driving, or at idle, or both?
I hope that gets you started. Can you take some pictures inside the engine compartment? Someone might notice something obvious.
• Yes the thermostat housing, engine block and heads. 255F. At one point fuel was vaporizing in the carb.
Fans turn on at 180 or 190 and run good.
36° total advance
No I have not drilled a hole but thinking of going to a restricter plate instead of actual thermostat.
It's a cast iron made for the corvette from O'Reilly's
Yes it is but the flow is not steady like it opens and closes kinda fast. Might be some air left in system but not much.
the spring is still in the lower radiator hose
Over heat is at both I will let it run and see what it goes up to without driving at all tomorrow.
Also I will take some pictures in the morning tomorrow of the engine bay. have heard of a air dam that is sapose to be in the front that is not there could that cause it too? Thanks for the advice much appreciated. I am so ready to drive with out the worry of overheating.
Looking forward to photos. I hope they show something obvious. Here's some of my 80 that sorta show the air dam. I also have the (stock) dual-snorkel CAI installed, which fills some of the space above the radiator. Foam fills the rest. Without these pieces, a lot of airflow bypasses the radiator.
36 degrees total, mechanical timing, right (with the vacuum advance disconnected)?
Here is also a similar thread with some additional things to check. In that case, it was the fan clutch, but that won't be your problem.
Nice yea I definitely probably need the air damn than. Thank you. Have you done anything extra done to yours?
More suspension work than anything else. My car was a numbers matching L48 4-speed project that needed everything, but I was able to drive it home. My build page is linked below.
As for heat related changes, my car overheated and had run-on/dieseling when I first got her. I fixed that with a Lars-style tune. I've since added sidepipe headers, dual-Spal electric fans (on at 195, off at 185). a new water pump (ACDelco 252-585 from RockAuto), high flow 180 degree Milodon thermostat, with a tiny hole drilled, and I have a stock dual-snorkel CAI with the flappers removed (so "cold" air all the time). The only remaining vacuum hoses do the headlights, brakes, PCV, fuel vapor canister, and manifold vacuum for the distributor vacuum advance.
Driving around, my car never gets above the thermostat temp. The fans do not come on unless I'm at a light or stopped in traffic, and then they cycle.
I can't find it on Eckler's site now, but the front panel piece must have been replaced by a PO. Perhaps it is still available. Here are the front spoiler extensions, but you may need the panel itself.
Yup no extension or panel just went outside to look definitely not getting enough air when moving. I thank you for the link I found the panel too. Ordering them now
It's easy to get air trapped. You can add coolant into the thermostat opening, with it removed, or add it into the heater hose where it connects to the water pump.
I assume You meant numbers matching L-48 4 speed and not L-82. There is lots of info on overheating on this web site if you use the search feature. What immediately jumps out at me is the Aftermarket Radiator which might fit poorly and generally means the surrounding foam insulation has been thrown away. Aftermarket water pump why ? Not using water with antifreeze why ? It sounds as though You might be going down the band wagon of making everything better than GM did. The early BB C3's had over heating issues and GM fixed them. As emissions came in it only got worse but GM kept up with it. These cars were deigned with the low front end that we all like which forced the engineers to lay down the Radiator which didn't help air flow. We have way more congested traffic now than when they were built and yes the temperatures might be higher. Did the car overheat when it was still numbers matching or only after everything was made better ? Gm concentrated there efforts on getting air to flow threw the Radiator I would do the same.
We have no idea of the type of water pump you are using, the radiator design you selected, whether you have installed a (proper) shroud to use with those fans, whether the fans have the 'real' capacity to move adequate air through that radiator, nor several other pertinent bits of data regarding your engine, how it is connected to vacuum advance, whether the vacuum advance even works, etc. etc, etc.
How would you like us to assist you????
We have no idea of the type of water pump you are using, the radiator design you selected, whether you have installed a (proper) shroud to use with those fans, whether the fans have the 'real' capacity to move adequate air through that radiator, nor several other pertinent bits of data regarding your engine, how it is connected to vacuum advance, whether the vacuum advance even works, etc. etc, etc.
How would you like us to assist you????
thanks for the help all. I figured a bit out. The air damn and everything under the front bumper like the air dam. The radiator is a single pass 3 row aluminum from corvette mods. With duel pull fans I belive 12" not sure with re measuring and it is shrouded properly. I have a stock water pump just new.. The vac advance is connected to distributor. I am no longer overheating at idle staying at 180 to 190. I had to heat wrap the headers to drop the temp when the hood was closed. And with the air dam and vln numbers are still matching. Just rebuilt the stock into a 383. With air dam and everything helped alot.
Late in, but I can confirm that air dam makes a huge difference. Ran mine for several years without as it was never installed by the dealer. Apparently they didn't ship with them installed due to likelihood of dinging them on the truck ramps. When I finally installed it the running temp dropped about 20 deg.
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Slideshow: A Jaguar designer's personal project imagines what a modern front-engined Corvette might look like if Chevrolet revisited the golden age of the Stingray.
1980 C3 L82 overheat
