Overheating Issue

[Gerald C.]

My 1963 has a 160 degree thermostat, fresh antifreeze and good flow. However, if I drive down the highway the temp gauge goes to 220 and more. When I'm on country roads, the car cools down to about 180 degrees. The fan moves freely.

Any thoughts?

Thanks,

jerry

[John H.]

Re: Overheating Issue

Gerald -

Step #1 is to verify that you really have a problem - take an I.R. gun shot of the radiator hose just above the thermostat housing and compare it with the gauge reading at the same time so you know what the gauge is really telling you.

[Paul B.]

Re: Overheating Issue

Jerry,

Just had exactly the same symptons on my 56, did an antifreeze / CO test and the head gasket has gone. Sometimes a plugged radiator can give the same effect.

Paul.

[Timothy B.]

Re: Overheating Issue

Jerry,

The thermostat has nothing to do with the high temperature unless it's not opening and in this case that's not your problem. If the car is not puking fluid out the overflow I think your OK. Make sure your expansion tank cap is holding pressure 13lb, and make sure the expansion tank is a good half full when the engine is cold.

The temperature sender/guage could be off just a bit so if you have access to a IR gun double check the thermostat cover for temperature and compare with guage. Does the car run hot slow driving in stop and go traffic and has the original aluminum radiator been changed?

[Stuart F.]

Re: Overheating Issue

All good questions guys, and I'll be watching this one close as I too have a 63 w/a 160 thermostat. I check mine with an IR gun before I put it away after a drive to monitor both my cooling system and exhaust temps. I used to see over 100* difference side to side in my manifold temps until I wired open the heat riser butterfly. My radiator was last changed in 75 so I'm watching for signs of plugging as well.

Stu Fox

[Duke W.]

Re: Overheating Issue

My 1963 has a 160 degree thermostat, fresh antifreeze and good flow. However, if I drive down the highway the temp gauge goes to 220 and more. When I'm on country roads, the car cools down to about 180 degrees. The fan moves freely.

Any thoughts?

Thanks,

jerry

Tell us about your radiator. Is is an OE 316? Date code? If not what is it? How old is it? What kind of coolant replacement schedule has this radiator seen since it was installed?

Duke

[Gerald C.]

Re: Overheating Issue

Thanks to everyone for their responses.

1. There is no fluid coming out on any overflow.
2. I just got the car and the radiator has no marks of corrosion, etc. I haven't seen the radiator markings yet.
3. I don't know what an IR gun is.
4. The car is hot, but no signs of "boiling"
5. Could I have a fan clutch issue

Thanks,

Jerry

[Gary C.]

Re: Overheating Issue

Thanks to everyone for their responses.

1. There is no fluid coming out on any overflow.
2. I just got the car and the radiator has no marks of corrosion, etc. I haven't seen the radiator markings yet.
3. I don't know what an IR gun is.
4. The car is hot, but no signs of "boiling"
5. Could I have a fan clutch issue

Thanks,

Jerry

Jerry, reference your #'s. Gary....
3. IR gun is an infra red temp gun such as RayTek MT4
http://www.amazon.com/Raytek-Non-Con.../dp/B0002198GY
A temp gun can be used to verify that the temp guage sender is accurate by comparing the readings with a temp gun taken at the radiator hose just about the water inlet connection
5. Fan blade should be resistive to move when the engine is hot and easy to move when the engine is cool.

[Stuart F.]

Re: Overheating Issue

Jerry;

You say you just got the car. Did this overheat condition occur after you did maintenance, like changing the coolant, or was it that way from the getgo (when you first got it)? If it was that way when you got it, I assume from a previous owner, have you checked with them as to how it was acting before and what kind of maintenance they may have last performed. there are a lot of areas you may have to troubleshoot in order to locate the problem, and the more you can learn about the maintenance history the better.

Stu Fox

[Duke W.]

Re: Overheating Issue

Thanks to everyone for their responses.

1. There is no fluid coming out on any overflow.
2. I just got the car and the radiator has no marks of corrosion, etc. I haven't seen the radiator markings yet.
3. I don't know what an IR gun is.
4. The car is hot, but no signs of "boiling"
5. Could I have a fan clutch issue

Thanks,

Jerry

The most common cause of highway overheating is insufficient radiator heat transfer capacity. This can occur to old OE radiators because precipitates from the traditional "green" antifreeze build up deposits in the tubes, which act as insulators and substantially reduce heat transfer performance.

Many old Corvettes also have bolt-in aftermarket brass replacement radiators that can be recognized by having soldered side tanks. These designs have 30-40 percent less heat transfer performance than the OE "316", so even when new they have very little margin. The 316 does not have side tanks because it is a furnace brazed aluminum matrix - like an aviation cooler. That's why they have the remote expansion tank.

If the car has a brass radiator it can probably be rodded-out by a radiator shop. An OE 316 radiator is not field reparable due to its construction.

If you need a new radiator a Dewitts 316 repro is the only way to go if you want reliable cooling. It is a very high quality piece and can even be date coded for your car.

GM used premium parts in the Corvette's cooling system for good reason. The clutch fan and aluminum radiator were very high-tech for the time and still are. Big engines in a relatively small envelope require special attention to the cooling system. GM did their homework and cooling problems such as yours are best corrected by bringing the system back to as new configuration and performance.

You should also check clutch fan function and the spark advance map, and use Zerex G-05 HOAT antifreeze. The archives are full of antifreeze discussions.

Duke

[Gerald C.]

Re: Overheating Issue

Thanks everyone. When the car stops after reaching about 220 degrees, there is no spillage of antifreeze. I just bought a new sensor, let's see how that helps. If not, I'll do the fan clutch. If that doesn't work, I'll watch everything until the winter and pull the radiator.

I'll keep everyone posted.

Thanks,

Jerry

[Gary S.]

Re: Overheating Issue

Thanks everyone. When the car stops after reaching about 220 degrees, there is no spillage of antifreeze. I just bought a new sensor, let's see how that helps. If not, I'll do the fan clutch. If that doesn't work, I'll watch everything until the winter and pull the radiator.

I'll keep everyone posted.

Thanks,

Jerry

Jerry,
You said some things that cause me to question your evauluation techniques. Several posters suggested verifying the temperature PRIOR to doing an R & R, remove and replacement, of parts. If you don't want to spend the money on an IR gun, then drive to your nearest radiator shop and see if they will do it. Also, another source for a test is a local volunteer fire department - they usually have very sophisticated IR guns and may help you out. In addition, there are lots of posts where owners have had issues with over-the-counter temp sensors since they are not properly calibrated. I thought I rememberd reading that Lectric Limited had calibrated temp sensors.

It was suggested that you probably do NOT have a fan clutch so why would you change it out? Fan clutch operation, as I understand it, is a slow speed issue and not a driving issue. If you are cruising along at highway speeds, you could remove your fan and clutch and just let air flow, caused by the forward vector, do the work. The fan only works at slow speeds when insufficient air flow is available, such as stop and go driving.

Yes, you can replace the radiator with a great unit from DeWitt but if it isn't faulty, why do it. Fwiw, my 66 had real heating issues at highway speed and a new radiator solved my problems. Like Duke said, IF your radiator temps are high (you won't know until you check) then you have insufficient heat transfer. Prior to pulling the original radiator out of my 66, there was a perceptible difference in the radiator, just by feel.

Again, to beat this dead horse, verify things before you start spending money on parts.

Gary

[Stuart F.]

Re: Overheating Issue

Gary;

Good advice. I know I'd be lost without my IR gun. I picked mine up at the Sun-n-Fun at Lakeland, Florida a few tears back. They are a must in aviation, as you probably know well. I see your C-130 in your heading. Did you fly them? I have two sons who flew for 10 years in the USAF in C-130's - one was head eval. pilot on AC-130's at Hurlburt. They are both now with JetBlue (the Fox twins).

Stu Fox

[Jim T.]

Re: Overheating Issue

Gerald speed do you travel down the highways in your 63 versus the speed you drive on the country roads? If your rear end is a 3:70 or worse a 4:11 you would be turning some good engine RPM's at 70-75-80 mph on the highway.
I don't get my 68 327/350 M21 3:70 out on the interstates for much traveling but the last time I did was in July, air temp was 105 and I was driving 70-75.
Have replacement copper radiator I installed in 1974 and my temp guage was showing 210 at 70 and about 215 or so at 75 that day. With a 3:70 rear gears the RPM's at 70-75 produce more engine heat.
The guage usually stays at operating temp stays about 180.

[Gary S.]

Re: Overheating Issue

Gary;

Good advice. I know I'd be lost without my IR gun. I picked mine up at the Sun-n-Fun at Lakeland, Florida a few tears back. They are a must in aviation, as you probably know well. I see your C-130 in your heading. Did you fly them? I have two sons who flew for 10 years in the USAF in C-130's - one was head eval. pilot on AC-130's at Hurlburt. They are both now with JetBlue (the Fox twins).

Stu Fox

Stu,
What a coincidence. Yes, I flew C-130's - for 25 years, both active duty and Reserves. AND I also fly for JetBlue. I will have to look up your sons. Ok, just looked them up. Would that be Brady and Brian?

The only time I have had need for an IR gun while flying was an indicated (but false indication) brake fire. The gauge was showing 700-900 degrees C . After an emergency return to the airport, the fire team shot the brakes with their IR equipment and it showed that they were ambient temperatures.

I have used my IR gun to calibrate my wife's oven, the outdoor thermometer as well as multiple checks of engine temperatures.
Gary