My 1972 LT1 runs hot all the time and will occasionally overheat.  I have had the thermostat replaced and changed out the antifreeze but that did not help.  I am wondering if having the radiator repaired or replaced is the next step.

Jim

(Jims72LT-1)

If it's O.E.M. most definitely!  Check for all rubber/foam inserts on the perimeter of radiator. If they are not there, they allow air to go around radiator and not through it.

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Thanks, I know the foam between the top of the radiator and the hood is there but I will double check the rest.  If it's not that it, would you replace with reproduction or have the existing radiator reworked?

Depending on your future of the car, and what you want to do with it. If not a desire to keep it original, I would go with a new aluminum one. "BE COOL"  "DEWITTS" and others have exceptional products. A 40+ year old radiator is on its last legs, and is not financially feasible to rebuild. 

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Good morning,I have a 78 Pace Car and have done extensive work on this 35,000 mile all original one owner car.This car sat in storage for over 10 years.She’s a beauty now.

 I changed out the radiator with a custom fabricated “Entrophy” duel fan ,I use the “Evan’s” fluid system.I’ve put a Hi-P.O. “Sanden” compressor and water pump on it.Ive just changed out the Harmonic balancer and went to a duel gear timing chain.

 I live in TampaBay and heat was always the issue with the C3 vettes.This conversion in 90 plus degree keeps the car at 165-185 with a/C running.It wasn’t the least expensive route but I can run this car anytime anywhere now.

P.S this is just one of the modern upgrades I’ve done to this car over the last two years since Ive owned it..Your welcome to call me to talk about what I’ve done anytime (KevinH 727-593-4504C/727-470-9680H)

I use “VetteWorks” Sergio Fernandez company in St.Petersburg who specializes in Corvette restoration,(parts at cost and $75 hr.) he is also a Top Flight  national judge.

 Travel safe !

Kevin, thanks for your reply.  Your car sounds well prepared for the heat. 

I prefer to keep my car as original as possible.  I am leaning toward a reproduction unit as close as possible to the original.  My car does not have air conditioning and I can deal with some heat.  I just want to avoid spitting out antifreeze (LT1s do not have an expansion tank).  

Jim

Actually, the LT-1 radiator does have an expansion tank.  It is the top 4-ish inches of the radiator.

My LT-1 has a/c and the only time I have a temp problem is at a stop light here in N. Texas.  And that is in the heat of the summer with temps over 98 degrees.  I often wonder if the water pump impeller vanes are all there and not rotted away some.

I put a DeWitts exact fit aluminum radiator painted "Black Ice" and it looks exactly like the old copper and brass.  Cools much better.  Lighter too.

When I flush my radiator, I just fill it to the rim and let it puke until it seeks it's own level which is where the normal level should be.

Gary

I really appreciate your response and congratulations for having one of the 240 LT1 corvettes with A/C.  I knew that there should be some room between the top of the radiator and the fluid level (although I never heard it described as an expansion tank) and I like your method of having it seek its correct level by filling the radiator and having the engine displace what shouldn't be there.  

The impeller on the water pump is a possibility but I intend to replace the original radiator first.  What temperature does your car run at?

Jim

When it is not hot out, it runs at about 180.  Summer time if I am moving, it stays just below 200ish.  That's according to my gauge, who knows how accurate the are.

Being a convertible, mine is 1 of about 58 out of the 240 total.

It's also a convertible with air, and it works. 

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Hello, I own a 72'. It is not a real LT1, but has been rebuilt to LT1 standards. I have a DeWitt radiator and it runs 195 in traffic at most speeds. It is not as hot as Texas, but is consistent in hot weather. It is also a convertible and has air that works. 

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Is gauge reading correctly?

An "out of the box" question - have you checked the tuning, specifically the fuel delivery?  I thought I had a cooling system issue with "BLKBRRD" as it was consistently running hot, no matter what the outside temperatures were.  Had the stock radiator checked (it had been rebuilt a time or two) and it was fine.  Tried different thermostats with no success (didn't expect that they would make a difference).  Finally discovered that it was running very lean, which was the root cause of the overheating. 

Most recently have discovered that the distributor was failing internally and it is in the process of being replaced.  When I get the car running again it will be interesting to see if there is an overall improvement in the performance.

Jim Olson 

"The Toys"...!!!  Save the Wave!

Where I've been in a Corvette...!!!

I think the ethanol in our gas causes it to run slightly lean. 10%?

Thanks for all the responses.  I am not sure if the gauge reads correctly but I suspect its pretty accurate as the car overheats when the gauge is at the maximum.

As for the car running lean, I am not sure.  I have had it serviced several times at a local Corvette specialty shop.  I have had the carburetor rebuilt, the valves adjusted, and have replaced plugs and wires.  I have to assume that they have checked everything out engine wise as the car has never run better in the 15 years I have owned it.

At this point I think I will wait until spring and replace the radiator. 

Thanks again for all the feed back.

I would make sure the gauge and sending unit are working correctly

My '75 Stingray 350/330 cruises at 190° F on a cool day and approximately 205° F on a hot day. 

I have a 190° F thermostat. If I run the air-conditioning on a hot day, my temp gauge indicates approximately 210° but not in the red, it doesn't seem to affect the engine performance. 

Personally, I think either the cars cooling capacity is either a poor design, or the temperature gauge may not be accurate as designed.

From what I've read in past C3 forums on the internet, this is a common issue. You might take a laser temp sensor and check your engine & radiators under the hood temp, then observe the cars temperature gauge to see if they are close.

You might have to add an external electric cooling fan to help, run 50/50 antifreeze, and of a 180° thermostat if needed.

Hope this is helpful!

I have read that besides the fuel-air ratio, timing and advance can affect engine operating temperature.

1973 L-82 4 spd

My LT-1 is timed to 16 degrees btdc and I am using manifold vacuum with a B28 vacuum advance can.

I run 12° static advance. I forget how much that vacuum advance adds to that but that's mainly at idle and slightly above. I have light springs and heavy weights on mechanical so that advance is all in by around 1800 RPM.  No AIR or EGR. 

That may all change when I get the engine put back in the car because I went from 9.0 compression ratio to 10.0 CR and a slightly more aggressive roller cam .  But I intend to run alcohol-free gas and you can only get that in mid-range and premium around here.

1973 L-82 4 spd

Thanks 73 Shark and F4Gary

I appreciate the info.  To be honest its over my pay grade but io will share the ideas with the shop I go to.

Jim

UPDATE!  Thanks again for all who posted ideas and suggestions.  I did end up replacing the original radiator with a DeWitts Direct Fit aluminum radiator.  It was past 52009 from Top Flight Aoto and it fit perfectly.  I replaced the hoses and shroud foam with part number 39859.  The net result is that the car runs perfectly with the needle indicating a steady 180 degrees.  My only regret is not having done this 2 years ago.  Thanks again to everyone that offered advise and assistance. 

Thanks for the update! Glad you got it resolved!

-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry 
C4 Vette Registry, C6 Vette Registry

My first Vette, now owned by JB79:

 On my '72 350 base with A/C, I had the original tanks fitted with four row tanks 22 years ago. Stock fan and clutch.  The temp gauge bareley goes past the first line, just past it in traffic... I live in Los Angeles...

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