Last fall my 31 over heated after a short drive so a friend and I removed the thermostat which was bad. I thought the problem was solved. When I pulled all of the cars out of the garage earlier this year I left them running for about 20 minutes and the 31 over heated again. I didn't think much about it until today when I took it to fill the tank for a long run Sunday. The trip was about 1 mile and as I got back home it over heated again. What do I check next? The water is coming out of the over flow on the radiator.

the water pump circulating the coolant properly? I've also heard that the cores in old radiators go and not properly cooling down the fluid.

I checked the belt and it is tight enough to turn the water pump which seems to turn and operate right when the engine is running. However the last short drive I did hear a tweetie bird sounds for a couple of seconds. I'm not sure what that means though. I also checked the oil to make sure it was where it should be. Water flows easily out of the petcock. I just got back from another short drive about two miles and a small amount boiled out. The temp gauge is in the normal range but I know those can't be trusted.

It is easy to over fill the rad and when the coolant expands it comes out. I fill mine so it just covers the top of the core and check it regularly. I bought an inexpensive infrared thermometer from harbor freight that has been a big help with over heating issues.


Dave

If the needle on the temperature gauge moves as the coolant heats (engine run) it more than likely is reading close enough. I suspect either the radiator was overfilled if it pushes the coolant out when driving at speed. However, if the coolant is pushed out when the engine speed is reduce to an idle or near idle it is more likely air is getting into the cooling system. Major culprit is air drawn in past the shaft on the water pump. That air heats and when the internal pressure in the engine is reduced dramatically expands pushing out coolant. It is a common problem. Solution is to make sure that there is enough lubricant on the water pump shaft to seal it and/or reduce the gap between the shaft and housing.

Another possibility is a cracked head or failed head gasket. If exhaust gas gets into the coolant, it will overheat and/or force coolant out of the system.

Thank you all for the hints and advice. I may well have over filled the Rad and I will lube the water pump. I'm keeping my fingers crossed it isn't a head or head gasket problem. We are supposed to go on a 30 mile trip tomorrow, I guess that will tell a lot of the tail.

Last spring the first few times started driving the 30 coupe after restoring, had an issue of overheating and over flowing it appeared to be from over filling. since then have had no over heating. Remember to use distilled water and water pump lubricant...….

One way to tell if it's a cracked head or gasket is to smell the exhaust. If it smells like antifreeze, then you're coolant is getting into places where it shouldn't. Had this happen on my daughter's Cavalier. Ended up just donating the car to charity and even the guy who picked it up could smell the antifreeze in the exhaust.