My '64 coupe OEM 327/365 has recently developed a severe overheating problem after historically running cool. I have checked all of the obvious including ... the water pump, flushed the cooling system, boiled and leak tested the radiator, removed the thermostat and re-set the timing. It still heats up quickly and stays there. Any suggestions what to check next or a solution will be greatly appreciated! THANKS, Fred
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Re: 327/365 OVERHEATING PROBLEM - HELP!
Fred:
Please provide more info. Has anything been done which might be causing the condition? How long since you last started and drove the car? What do you mean by "overheat"..... this has different meanings to different people. Many folks, myself included, say "running hot" when the temp gauge is above the comfort zone, and "overheat" when it actually boils over. Are you using an infrared temp sensor to verify the gauge reading? You should aim the IR beam at the base of the temp sender, or the base of the t-stat housing (only after the t-stat opens, otherwise you'll get an improper reading). Did you recently change your temp sender? It can be a lot of things. Does it happen while moving, or standing still? Tell us everything that you can think of, no matter how stupid you think it might sound.
Joe -
Re: 327/365 OVERHEATING PROBLEM - HELP!
Joe, Overheating is defined as boiling out the overflow, so not likely just an improperly high reading from a bad sender or gauge. THANKS...Comment
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??? *NM*
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Re: 327/365 OVERHEATING PROBLEM - HELP!
Everybody has their own definition of overheating. How about providing some real detail?
What is the gage reading?
You say it's loosing coolant out the overflow - while the car is running or after shutdown?
Do you know what the proper coolant level is in the expansion tank?
Garbage in garbage out!
DukeComment
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Re: 327/365 OVERHEATING PROBLEM - HELP!
Thanks Duke, but I was looking for help from anoter Corvette enthusiast, not a lecture. As I said, it's boiling over (50% glycol mix), so not likely a faulty sender or gauge. This occurs when running and the temp gauge is pegged. The expansion tank is kept half full. Thanks for any ideas for other things to check. FredComment
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Re: 327/365 OVERHEATING PROBLEM - HELP!
Fred, you won't get any better advice from Duke, Joe and others. But you never answered any of their original questions other than to seem a bit confrontational. Has anything been done to the car prior to overheating? Have you tried a IR temp gun pointed at the radiator to determine if it is plugged. Any modifications to the car? The more information you give, the better the good guys and gals on this board can help.
GaryComment
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327/365 OVERHEATING PROBLEM - HELP!
Gary, Not trying to be confrontational, but thought Duke was. I am a backyard mechanic who has owned four 'vettes over the years, not and professional tech. There were no mods prior to the problem, however the car was sitting for long periods between uses. That's why we flushed everything and pulled the thermostat. I do not have an IR thermometer, but the fact that it's boiling over would indicate a coolant temp greater than say .. 230 degrees with a 50/50 antifreeze mix, not improper gauge reading from sender or bad temp gauge. Thanks to you and the others for their assistance. FredComment
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Re: 327/365 OVERHEATING PROBLEM - HELP!
I think you will find that everyone on this board will help you as much as they are able. Duke is one of the good guys to ask and he is able to answer MANY more questions than most. I believe that most of the "gurus" want as much information in the original post to be able to help us diagnose our problems. Symtoms, temperatures, modifications, numbers, etc - all that may be affecting whatever it is that we are trying to fix or diagnose.
Just an FYI, I had similar indications in my 66 327/350 with original radiator and cooling system. It required a new DeWitts repro radiator before I could drive my car on the highway. I had a temperature differential between the bottom and top of the radiator that was easily discernable just by putting ones hand at the top and bottom of the radiator. I guess aluminum radiators were never meant to last 30+ years.
GaryComment
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Re: 327/365 OVERHEATING PROBLEM - HELP!
If she's puking coolant while you're driving (vs. in the garage after engine shut down), I BELIEVE you when you say you've got an overheat problem! The first thing I'd do is check for pressure leaks in the system. Stant makes a handy-dandy pressure checker that most shop mechanics have (or have access to).
The device is a hand pump with a pressure gauge and adaptors. One adaptor lets you remove the rad cap, install it on the pressure checker, pump 'er up and watch the gauge as the cap is exercised to its rated 'pop' point. This will tell you whether your rad cap is good/bad.
Next, you can use another adaptor to connect the tester to the radiator in place of your rad cap. Now, you're monitoring the actual coolant system pressure and you can use the hand pump to boost pressure above normal if you don't immediately find faults in the system (faulty rad hoses/clamps, faulty heater core hoses/clamps).
Last, something as simple as a chunk of 'crud' (high tech term) trapped between the rad cap gasket and the radiator's filler neck seat can generate a leak point passageway. These are the kinds of problems we LIKE to find!Comment
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Re: 327/365 OVERHEATING PROBLEM - HELP!
Fred your bottom radiator hose could be restricting flow if the steel wire spring inside has failed allowing the hose to collapse. Also check the archives for some of Duke's posts on how a vacuum advance unit can affect engine temperture. For some the vacuum advance recommendation corrected their heating problem.Comment
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Re: 327/365 OVERHEATING PROBLEM - HELP!
Fred -
What type/age of radiator is in the car - the original aluminum Harrison, copper/brass replacement, or ?? You indicated you had removed the thermostat - did you re-install it or replace it? It's NOT a good idea to run without one, as it's a calibrated orifice to modulate coolant flow. Is the temp spike any different between in-town slow traffic and highway driving?Comment
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An inexpensive test
Fred,
With the engine cold, disconnect the top radiator hose at the rad. See if it is full of coolant or full of air. The expansion tank half full mark is well below the top of the radiator, making it hard to get air out of that top hose. Re-connect the top hose. Then you can use vacuum on the small hose on the top right of the rad to pull that air out. Then over-fill the tank and just let the extra coolant run out the overflow into a pan until it stops (two or three trips around town).
MikeComment
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Re: 327/365 OVERHEATING PROBLEM - HELP!
John, It is the OEM Harrison aluminum. I did not replace the thermostat, but you are the second respondant that suggested that I do so. One said it is necessary to minimize "foaming" of the 50/50 antifreze mix. What temp thermostat should I install? It overheats in highway and stop-and-go equally. Thanks, FredComment
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Re: 327/365 OVERHEATING PROBLEM - HELP!
Fred- Sounds like a intake manifold gasket failure or possibly a head gasket.Comment
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