Q: Car overheating

There are many gaskets on your car; there is no way for me to tell which gasket the coolant is shooting out of without directly inspecting your car.

I can say that it is not common for a head gasket to leak externally. It does happen, but when we say it "blew a head gasket", coolant is leaking into the combustion chamber and being turned into steam that exits the tail pipe in a white cloud of steam. So, if you don’t see steam coming out of the tail pipe, it likely isn’t a head gasket. It still may have blown a head gasket as a result of overheating, but that would be a result of the low coolant level from a coolant leak.

Anytime a car overheats, the thermostat should be replaced. Thermostats are damaged when they get too hot. It may not be necessary to replace the thermostat every time, but it is such a cheap component that has such an important function for the car, it will save you money to replace it.

The first thing that must happen is the leak must be fixed. Many times we can’t tell if the head gasket has been damaged without a working cooling system. Head gaskets, contrary to popular belief, do have degrees of failure. Some only become problematic under loads such as climbing a long grade. Some don’t show until you have been driving in hot weather for an hour or so. And some are so bad that the car is unable to run.

An experienced technician is usually able to make a fairly quick determination about a head gasket, but often it isn’t possible without fixing the cooling system leak and test driving the car under a load condition. I have personally spent hours chasing a head gasket that a customer’s description suggests is occurring, but it’s a big and expensive job, so we are reluctant to say it is a head gasket without a firm confirmation it is indeed the head gasket with the problem.

I recommend having your car inspected for a coolant leak, and see if it overheats after that.

Good luck!