Overheating Engine (Part 5)
Q: Overheating Engine (Part 5)
I have tried everything suggest but I just can not find the problem to my overheating problem. I am about ready to give up and move north. Any ideas?
A: One guy on the post (forgot name) may have been close when he suggested that over heating in the first gen birds was due to the design of the cars front end. An old time radiator man I often go to said that the firebird radiators are the smallest ones Pontiac has ever put in cars and expected them to do so much ie. cool big V8s.
This guy also had an excellent tip for a mysterious overheating problem. All you overheaters may be over looking the old head gasket leak.
A head gasket can develop a small leak near a water jacket. The problem may not effect the performance of the car and often is undetectable until the overheating starts. When the leak in the gasket develops between the combustion chamber and the water jacket, a small amount of compressed air is forced into the coolant while the engine is running. The results are large pockets of air forming where the water should be and turning to steam from the hot spots in the block. The results are overheating followed by blowoff over flow.
The check the old guy gave me goes like this: Disconnect the fan belts so the water pump will not turn. Disconnect the top radiator hose at the radiator and hold it up vertically while filling the radiator with water until you can see the water in the end of the hose you are holding. While everything is cold (engine, water) start the engine and watch the water in the end of the hose for small bubbles. They will appear before the hose gets to hot to hold and the indecate a bad head gasket.
This whole deal works. I used it on my 1969 and found the cracked gasket…Old radiator Bill impressed me on another occasion when I plopped down a radiator in his shop and he eyeballed it for a few seconds and proclaimed, ” that’s from a 1967 GTO!
Good luck with the heat
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I agree with the last comment in regard to blown head gaskets, they do have a strange way of showing up until the gasket completely lets go then you will have coolant spewing from the radiator or over flow tank then you have a culprit. My personal experience in Oz is firstly check timing, have your rad cleaned and checked mine was 40 percent blocked, fitted back to my car still to have it reach close to 200 degrees sitting at lights idling but mostly fine when driving, I replaced the 8 bolt water pump (cast impellor) stainless backing plate, adjusted the plate clearance, replaced the coolant and thermostat still not much difference, ordered new 3 core aluminium rad from USA fitted perfectly, much improvement on the old radiator with normal driving and stopping until I drove it in 40 degrees celcuis still doing the same thing at idling and going up long hills.
I did some more research after reading what other people had done and come up with the idea that it is still related to the water pump poor efficiency due to the backing plate and water pump not being integral (sealed unit) so I searched for a smaller pump pulley and found a 9788886xt from a GTO also used if you have A/C, pulley went from 8″ to 6 1/2 had to replace the alternator belt, the old one was recycled for the power steering.
Went for a long drive along highways and up mountains (only reached max of 180) stopping and idling all good, it is early days but it seems to of made a big difference. I hope this has helped so before you rush off and through money at it check the basics first, then move to the next step.
1968 Firebird 350 2bbl 2speed auto.