William Buckley

Just purchased a restored C2 coupe (327/300hp) with auto tranny, AC, power steering, power brakes, and found that it has the same problem that I have heard about previously ..... over heating in city traffic with 98 temps outside. New restoration included new radiator, new thermostat, new water pump, so I assume that the problem can be corrected with a thermostatically controlled electric radiator fan. Any suggestions would be appreciated if you have other ideas for solving my problem.

Nowhere Man

What's your definition of overheating? Have you verified the temp your reading? Have you read the articles written by our own JohnZ?

William Buckley

Overheating to me means the temp gauge starting to enter the "red zone" when stopping in city traffic. And I have not read precious articles on this subject, because I am not a "senior member" like yourself. Give me a break, guy. I just purchased the car and have just joined this website. That's why I ask experts like yourself.

Nowhere Man

Here is a link with all of his articles. Read the Corvette cooling 101. But did you verify the gauge with a IR gun. Those gauges are known to be wrong.

http://www.camaros.org/articles.shtml

Powershift

With a newly restored car, you really don't know what you have. Someone else built it.

1. You need to find out if you temperature gage is accurate. A wrong sending unit or a incorrect temp gage calibration could cause the needle to go into the red and yet the temperature is within acceptable limits. So first check your calibrations and actual temperatures with a good IR gun.

2. What radiator is installed?? If it is not a NOS original or a DeWitts aluminum reproduction, it may not have the BTU capacity needed. What is currently installed??

3. Engine timing and vacuum advance can play a significant role in overheating or not. You need to determine what your actual initial/mechanical/vacuum/total advance is and at what corresponding RPM.

4. AC cars have special seals and fan shrouds from the factory. Does your car have have all the special factory seals and shroud extension??

5. If your car is/was a K19 California AC/Powerglide car, then there are other things you also need to do to increase performance and cooling (at the same time). You can tell this from the engine stamp pad.

All of this has been asked and answered here over a half-dozen times each year......especially during peak summer months. There is a FAQ Section at the top of our C2 forum page that contains a lot of this information...so we don't have to repeat it each time someone asks. The JohnZ article should be part of this.........it may also be on the web if you Google "JohnZ" and "Engine Overheating Magazine Article". I will try and find it for you and post it as an edit. Then you can read it easily.

Electric fans may cure the problem, but should not be needed if everything else is right. Hang with us and we can help you.

Larry

EDIT: Here is the article. http://www.camaros.org/pdf/corv_cooling2.pdf And here is a another good one addressing another side of engine performance and cooling. http://www.camaros.org/pdf/timing101.pdf

William Buckley

Checked everything this morning and it looks proper. The car was sold at Barrett Jackson in 2006 after restoration, but that does not mean that something could have gone wrong between that time and now. Proper Harrison high capacity aluminum radiator with side tank, and the radiator has the proper shrouding. It is a California k19 car, but everything looks ideal under the hood with proper fan and cooling system. I am not a mechanic, so it will have to be checked for accurate temp gauge and proper cooling by a mechanic. Will run without AC in the hot south until I can get that done. Thanks for all the input.

Frankie the Fink

Guys on here really try to help but they can seem a bit abrupt at times...don't read much into it. Powershift's advice is spot on. There are lots of things to explore before you add one of those double fugly electric fans. Don't do a knee jerk reaction and add a non-stock part until you've worked through Larry's suggestions above.

William Buckley

Thanks for the advice. I'm going to take it to a recommended shop that works on vettes, and not going to go overboard in doing something other than OE set up. Do not want to modify the "original status".

66RBS

Check the C60 section of your AIM. This section deals with the AC mods. There are a lot of rubber seals around the radiator and shroud that force the air thru the radiator rather than bypass it

Note that AC cars have a seal on top of the radiator and an additional lower seal on the shroud. All to force more air through the radiator.

Not saying this is your problem but you want to direct as much air as possible through the radiator

Randy

Nowhere Man

You don't need to be a mechanic to check to see if the temp gauge is right or not. Just about any tool store sells a IR guns for less then 40 bucks. Go get your self one and get your car up to temp and point the gun at your upper rad hose and see if the temp on the gun matches the gauge. If so you know it's working. If not then you got some other options.

William Buckley

The aluminum high capacity radiator has a shroud that completely surrounds the fan ...... just like it is supposed to look. I'm taking it to a shop to have an IR gun reading, and then looking at a bad temp gauge or a thermostat being the problem. Thanks for your advice and concern.

Powershift

K19 cars with Powerglide (California cars) originally had an ignition map that was supposed to help emissions, but it DOES NOT help the engine run........especially hot and at idle. Add in AC and you compound the problem.

Over the years, many folks changed the advance system (mech and vac) to be more efficient and allow the engine run cooler and better. So if your car still has the original K19 advance curve, and it has auto, and AC, and it is a hot summer.......yes overheating is very possible.

But first check the actual temps with IR gun. Then check the entire distributor advance system (initial, mechanical, vacuum, and total) versus engine RPM. If you still have the original curve, then a decision point is reached regarding how to improve things. We can talk more at that time.

If I recall, the original curve had about 4 degrees RETARDED timing at idle (ATDC), a ported vacuum advance that didn't start the advance until the engine RPM was maybe around 1500 RPM or so, with a total mechanical advance (no vacuum....plugged) of 36 degrees at 5100 RPM. The original vac can produced 15 degrees of advance @ 12 in HG vacuum and 0 degrees at 6 in HG vacuum. I don't know right off what #number is stamped on the vacuum can, but can find it if needed. Tell me what you see on your car.

It is also possible that the K19 cars got the 195 F thermostat, which is a bit high for these cars.......especially with AC. A 180 F is much better.

Larry

EDIT: I would also check the kind of fan and fan clutch you have installed. A 7-blade (non-stock) fan may help. I have one myself on my factory air car. Also the fan clutch may be worn out or replaced with one that does not lock up until a higher engine temperature. A pic of the fan and fan clutch would be great if you can get it...........otherwise describe what you have.

William Buckley

I have the original owner's manual with the car. It says 6 degree advance at 500rpm and a 195 degree thermostat with the K19 California car. I'm sure that this does not help hot summertime temps. Already talked to a very trustworthy vette mechanic and he will take a look at the situation. My thought, and I hope that I am right, is the thermostat opening only part way. Thanks for your advice.

Powershift

Bill:

Need some additional information. Is your car a 1966 or a 1967?? That helps me to help you.

I know for a fact that 1967 K-19 automatic cars had 4 degrees ATDC. Only the manual trans K-19 cars had 6 degrees BTDC......also all non-K19 cars had 6 BTDC.

Now, if your car is a 1966 model, it is possible that the advance is what is shown in your Owner's Manual..........as there is some conflicting data on this. But my original point is still valid.......and that is you must map out the advance curve to really know what you have after all these years.

And, don't discount the fan and fan clutch questions I raised. They can mean the difference between success and failure.

Good luck.

Larry

427435

X2

Don't let any mechanic get their hands on the car until you know for sure it is overheating. They see $$$$$ whenever an old Corvette comes in. Harbor Freight has the temp guns as do any auto store. Very cheap investment.

irwiny

My 66 / 327-350HP w/AC non California car with original Harrison aluminum + fan clutch & 5 blade fan + Shroud (3/4 circle - missing last bottom 1/4 piece) runs about 185 w/AC off at 80 degrees outside.

One thing I did do was change from 195 to 180 thermostat. I have no idea why a 195 was installed. My car would run before at 200 normally and creep pass 210-215 on hot or traffic days. It still goes up but from 180/190 and not passing 210 anymore after changing the thermostat.

Be sure to run 50/50 antifreeze - Zerox G05.

If your IR gun test, timing and vacuum advance are fine, check some Vette catalogs to see if you have a correct shroud installed. After reading all of the excellent forum suggestions about running hot, I was lucky the fix was pretty easy.

Irwin

William Buckley

The car is a 1966 model with 327/300hp and an automatic tranny. Sold in California originally as a K19 car. Do not know if it has been modified since then, but the manual says 6 degree advance. Left the car this afternoon at a very trustworthy corvette shop. Will get word tomorrow what they find. Thanks very much for your help.

mblake101

Hey William - Welcome to the forum. Out of 6 c2's over the years, I've had two A/C coupes, that got hot sitting at red lights in Texas summers. One was corrected with timing/advance, the other finally cooled down after getting some miles on a fresh L36 engine rebuild. My current 63 Coupe showed hot as well during it first summer here, but I took the advice of great members and ran down to Harbor Freight for a temp gun. Low and behold, my dash temp gauge read 12-15 degrees hotter than it really was.....may not be your actual problem, but know this, these guys saved me big time in worry, headaches and $$$$$.
Good luck!

Mike

William Buckley

Shop said this morning that the 195 thermostat was not opening all the way, and installed a new 180 degree thermostat. Hope that this takes care of my problem. Thanks for the help from everyone. I will be back on if this does not solve my problem.

Nowhere Man

what did there IR gun read??