Took my 65 coupe for a short ten mile ride and she overheated . This is the first time out of the garage in 20 years. The original water pump shot craps so I purchased a rebuilt unit, keeping the original, removed the thermostat and still she overheats. Replaced the heater core sometime back, car runs extremely strong, but sometime runs on. What is happening can someone help?.............Joe
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Re: overhheating
the newer water pumps have stamped steel impellers instead of a cast iron one and they bypass too much water.the speed shops sell a brass disk that can be pop rivited to the stamped steel impeler to prevent the bypass. also make sure you do not have any air pockets in the water jacket. -
Re: overhheating
Removing the thermostat is the worst thing you could do. The thermostat, when open, restricts the rate of flow of water to give the water time to transfer heat to the radiator and from the engine components.
If the engine "runs on" you might take a look at the ignition timing just to make sure it's fine. Timing too far advanced will overheat an engine. Too far retarded will heat up the exhaust manifolds. Look at the points.
Sitting in the garage that long would suggest to me that at a minimum you should thoroughly flush the system and probably have the radiator looked at for restrictions due to scaling that may have been dislodged. If you have a fan clutch on it, test it in hot water to see if the fluid inside locks up at temperature.Comment
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Re: overhheating
Joe------
The most common reason for engine overheating, by far, is a deficient radiator.
If the engine primarily overheats at idle, then the cause may be a deficient fan clutch. Otherwise, I'd look to the radiator.In Appreciation of John HinckleyComment
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Re: overhheating
Hot or not the clutch fan freewheels very easily, is this an indication of a bad clutch fan?.................JoeComment
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Re: overhheating
Joe -
A correctly-operating fan clutch will freewheel much more when cold than when it's sensing hot air from the radiator. Did it overheat at highway speed, or in traffic, or ?? What kind of radiator is in the car? It needs the thermostat.Comment
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Re: overhheating
Fan clutches have a fluid inside that thickens with heat. When the assembly is cold, the fluid coupler inside is like water. When it gets hot it turns to a gel and locks the fan to match the speed of the motor.
An easy way to test a fan clutch is to take it off the motor, heat up some water in a pot big enough to drop it into, let it sit in the hot water for a few minutes, pull it out (without sticking your fingers in the hot water, of course) and with some gloves on see if it spins or if it's locked up.Comment
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Re: overhheating
I would also check the spring in the lower radiator hose. Sitting for as long as you state could cause the spring to disintegrate. The suction of the water pump can and will collapse the lower hose stopping the water flow altogether.
Hope this helps.
MarkComment
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Re: overhheating
Didnt see this mentioned. Along with all the other suggestions make sure all the radiator support seals fan shroud etc... are present and accounted for.Comment
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Re: overhheating
The radiator over heats at idle, then boils over. The radiator is an brass replacement that was flush and check for cooling ability. Thanks for all the ideas, will remove clutch and test in boiling water, where can I get another for the time being?........JoeComment
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Re: overhheating
Auto store about $45.00Comment
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Re: overhheating
hmmm, sounds all too familiar. I won't preach gospel to you, but rather relate my own overheat problem with my own 65 SB (L76). The prev owner seems to have lost his taste for the car within a year of buying it, I came to learn after buying it myself that it was due to an overheating condition that he just could not fix. And then he had a Vintage Air A/C system put on to boot - which he could never use on the hot days when he needed it, becuase the car would then puke coolant.
He tried: brandy new brass radiator, new wiz bang cooling fan, twin electric fans, new wiz bang high flow water pump, improper lower temp t-stat (doesn't everyone?), new fan clutch, etc. Al the receipts came with the car, I could watch the story of his efforts unfold before my eyes.
After making sure the timing was correct (it wasn't), I basicaly returned everything to stock - GM fan clutch, correct for 65 fan, correct water pump, replaced lower rad hose for good measure, correct 180 t-stat, took off the electric fans, removed the VA system (part of my plan when buying the car anyway, it's a vert) - and I had it so it was not puking coolant at every chance it got, but still running hot and still fearing getting caught in stop and go traffic on a hot day - progress, but that's no way to enjoy my pride and joy.
Then I took some sage advice (regarding the fact that these C2 SBs came with an aluminum Harrison rad, that is 30% more efficient at cooling than a new Brass rad - so I was in the hole by that 30%) and purchased a nice aluminum rad from Dewitts - I got their reproduction rad, looks just like the one that was in there in 65 - and I made a huge dent in the problem (actually I cured the problem, but here's another thing: don't put blind faith in what your temp gauge tells you) and once I finally got a good temp sender in there that was feeding accurate advice to my temp gauge (which I could only confirm by getting an IR temp gauge "gun"), I am a "steady 180" all day long, can idle for long periods sitting still on a hot day, you name it.
I personally think you will fight a losing battle, change a lot of things, but you won't beat it until you get the proper aluminum rad back in there. But that's just what worked for me, in my 65.
Good luck, I hope you are able to get that 65 running so you can take it out and not have to stare nervously at the temp gauge, but rather enjoy the car.65 MM Convertible, L76 (365 hp)Comment
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Re: overhheating
The PO's story has been repeated countless times and untold dollars spent in a fruitless effort to cure the "problem".
The "secret" is to be sure all components are OE spec and in good working order including the vacuum and centrifugal spark advance components. Sure, a copper radiator is half the price of the correct Harrison design DeWitts aluminum radiator, but it's just wasted money because a brass "look alike" won't do the job.
Likewise lower T-stats, electric fans, aftermarket engine driven fans to replace the OE clutch fan, "high flow" waterpumps, Water Wetter... ad nauseum.
Follow the "secret formula" - original equipment in good working order. It just doesn't seem to dawn on a lot of guys that these cars actually DIDN'T have chronic overheating issues when new, so maybe the basic design is okay, but there might be a problem with some component on a 40 year old car with no or only partial maitenance and repair records.
The cooling system engineers who designed and tested these cars actually knew what they were doing, and they did a damned good job!
DukeComment
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sometimes the answer is right in front of you NM *NM*
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