QuestionQUESTION: You helped me a while back with some electrical issues. Now I need to test you out on the cooling system.
My '50 Coronet keeps overheating. I have flushed the radiator and block. Replaced the thermostat. Checked that the water pump works. It still overheats. What have I missed?
ANSWER: Ok Roger, I need some more information so that I can zero in on the probable causes. When does the engine overheat:
1. When the engine is idling?
2. When sitting in traffic?
3. When driving at slow speeds?
4. When driving at highway speeds?
5. When climbing hills?
6. All of the above.
There are different problems and combinations of problems that will signal which part of the cooling system is causing the problem. Now, I use an infra red laser beam thermometer to check to be certain that the engine is really overheating and we do not just have a temperature gage problem. These are not expensive and can be purchased at Northern Tool for about $50.00. To use the infra red laser thermometer point is at the bottom of the thermostat housing. This will give you the accurate temperature of the coolant coming up out of the engine. Let me know the answers to the questions and we will go from there.
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QUESTION: All the above. It only takes it about 10 minutes of any driving to start to overheat. And it starts steaming out of the radiator cap.
AnswerMy first step would be to remove the thermostat and make sure that it was not installed backwards. I would then put it into a pan of water on the kitchen stove with a thermometer in the pan. The thermostat should be marked with the opening temperature. Make sure that the thermostat opens by that Temperature. Next make sure that there is a coil spring running the length of it inside. If the hose is the flex hose those keep the lower hose from collapsing. The lower hose is on the inlet of the water pump and there is a vacuum generated by the water pump with the engine running and will collapse the hose restricting coolant flow. If these check out drain some coolant out of the system until when using a flash light you can see the tops of the radiator tubes when looking down into the filler neck. Older radiator will grow solder blooms in the tubes that will restrict the flow. These will laugh at collapsing to try to flush them out. In these cases I haul the radiator out and take it to my friendly radiator shop to be flow tested. If the flow is low a replacement core is needed. There is a possibility that you have a blown head gasket. The check for this remove the fan belt. Fill the radiator to the brim. Leave the radiator cap off. Now start then engine and accelerate it. If the coolant squirts out then there is compression getting into the cooling system. Now using a flash light look down into the filler neck and accelerate the engine again, this time looking for bubbles in the coolant. If you see them then there is a small compression leak. Probably head gasket.
