If it overheats at idle, it isn't a radiator capacity issue. If it overheats at speed, it isn't from lack of airflow (not a fan problem.)

You still didn't say if this prob just started or not, but I think your water pump failed, or you have some blockage keeping water from the radiator.


If the problem just started, did you change something, or did it unexplicably appear?


You are not getting too fast of water flow, especially if the problem just started.

You said the Tstat works, you just changed it? is it opening fully?

Doug

 

Thanks Dennis. Would you suggest sticking with the motor driven fan or converting to electric (4139063M) ?

 

I have owned the car for only two weeks and the issue has been there the whole time. Now I know why the seller only wanted to meet after 730 at night. Other things like a 160 deg thermostat, 16# radiator cap, lockout tab on clutch fan, etc. lead me to believe that this issue has been around for a while.

The Tstat opens fully. Checked it in the kitchen first.

Good input Doug. Thanks

 

This may sound off the wall, since you've stated that you are running a #'s matching 327/365 engine, but, have you checked the block to make sure it is a 3782870 and not a 3858180. The 8180's were used in conjunction with the 2870's, but, had much thinner cylinder walls. If the overbore of .060" is done on an 8180, I'd be a little worried. Just a thought.

 

If you could post a few pics of your engine bay so we all could see your set up that could help. Do you still have the fan shroud and the seals for example. Is the fan correct or some aftermarket flex fan? Original distributor with full time ported vacuum? Just a few more specifics and we should be able to narrow this down a bit.

Dennis

 

Possibly a head gasket leak or cracked head. A block tester kit will verify if so, many shops offer this service, shouldn't cost too much, ot just buy your own, they are not expensive.

I would eliminate combustion gasses into the coolant first, then investigate things like water pump. The 16# cap is a combustion gas clue.

You can also leave the cap on loose (first notch) and drive the car and see if problem continues, releasing the gases into the air should slow or eliminate teh overheating, especially if you have a 160* Tstat.

Doug

 

What if Bubba put a reverse rotation water pump in? You would probably need to pull the pump to inspect the impeller.

 

Electric fan is just another fix to try and solve a different problem. You DON'T have an airflow problem, anything over 20 MPH, and you don't need a fan at all for cruise conditions.

Ah, the old meet at night trick. Kinda like the car is already warmed up when you get there to look at it trick. There is something being hidden, the question is, what?

Doug

 

 

Let's hope is only a couple hundred dollar fix and not a couple thousand dollar fix.

 

The fan is a clutch and I've also used a rigid racing fan, but I'm not certain about the distributor.

Here are the only engine pics I have at this time:

 

I know that the water is flowing correctly because the lower hose is 20 deg cooler than the upper hose.

 

Hang in there. Post some pics for us we can sort it out.


Dennis

 

Kits are only $25 bucks so that's not bad. Although I doubt that's the case. I haven't seen any oil in the water or water coming out of the tail pipes. Never hurts to check though.

 

I had a leaky headgasket/overheat problem once, and never had eitehr of those symptoms. It was a minor gas leak, car would over heat and puke coolant.

Doug

 

Here is some additional reading from just a few days ago. Same year as yours.
http://forums.corvetteforum.com/c1-a...g-problem.html

Dennis

 

Good opinion Miguel! Years back when building Hot Rods with lots of miss matched parts we would occasionally have to put a man made blockage of some sort into a cooling system due to too fast a flow threw the Radiator. Last time I mentioned this in a Thread, Barry, of Barry and Linda Fame ridiculed me for suggesting such a thing. Experience teaches us some things that Slide Rules contradict!
If I were the OP, I'd remove the Therm. and drive the car just to observe the result. Next I'd try filling threw the upper Radiator Hose and the Therm. Housing Port.. Never know, could be an Air Trap somewhere. (I know, highly unlikely). All Diagnosis Testing can be done with plain tap water for convenience. Keep us posted so we all learn something new. Al W.

 

Any chance the last owner painted it himself and clogged all of the fins?

 

Although not as good as a DeWitts repro, that Griffin radiator, in good condition, has plenty of capacity for your car's engine. My bride's track car runs this radiator which cools a 377 in full song lap after lap. On-track coolant temps have never gotten above 180.

That said, you might want to run your hand all around the front of the core to ensure that the whole radiator is participating in cooling the engine.

Jim

 

Borrow a rad pressure tester and test the system for leaks . Check it cold first, then warm it up and pump it up again .
My guess would be a cracked head or a head gasket and
the pressure test will show you if it has either one .

Bill