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Please help! :(

I have a 1999 Chrysler 300M. It is overheating in a strange way. After driving 3 miles it begins to overheat. Sometimes it will overheat, then quickly drop back down to normal temperature, but then overheat again. When going up any grade it definitely overheats.

I have had the car in for repair at two mechanics. Both have GIVEN UP on fixing the problem. Here is what they tried: Replacing both radiator fans, replacing the thermostat, replacing the water pump. The car is also losing coolant. None of these repairs has helped the problem what-so-ever. It’s a mystery. And I keep being deeper in the hole with money :frowning: What could it be?? Someone said it could be the temperature sensor. Is that true?

And no one replaced the radiator cap? That is step one for this problem.

“The car is also losing coolant”

Is this a visible leak, or is it mysteriously consuming coolant with no visible leaks?

If it is the latter, then you have to seriously consider the possibility that the engine has a breached head gasket. While head gasket problems can take several different forms, one frequent effect is an engine that runs hot. And, internal leakage can cause coolant to be “burned” in the cylinders, thus causing a drop in coolant level with no visible leaks.

I hope that the above scenario is not the case with your car, as you would then have to consider whether a 14 year old car was worth the repairs necessary to fix a head gasket problem.

But…here is another, VERY cheap possibility that I hope turns out to be the solution to your problem:
If neither of the mechanics has taken the very simple step of replacing the radiator cap, that is something for you to consider.

As far as the leak… I’m not sure where it’s coming from but I notice the coolant on the ground if I drive the car. I also already replaced the radiator cap and it’s still overheating :frowning: I keep putting money into the car and nothing has helped so far. Is it best I just get rid of it and cut my loses?


Is it best I just get rid of it and cut my loses?
Not necessarily, but maybe. If your problem is just a leak, then that could be simple and reasonably inexpensive to fix. As VDCdriver suggests, coolant can "disappear" into the engine and that could be serious, but the fact that you can see water on the ground is a hopeful sign.

Do you know if either of your mechanics did a pressure test on the cooling system? If not, then someone should do that. This test is quick and simple, should not be expensive. In fact, a DIYer could do it if you are so inclined or you know someone who might be. It enables you to pressurize the cooling system while the car is stationary, so that you can see if the system holds pressure, and if not, it will cause the leak to appear making it easier to locate.

I’d suggest that you do at least that much and see where the water is coming from. If you want to embark on that test yourself, people here can help you. Some parts stores, Autozone for example, have a tool lending system so you can use their tester and return it for a full refund.

If your mechanics have thrown parts at this without doing the pressure test, then their lack of competence is showing. Given your water leak, they should have known that the fans were not the problem, so you might be better served by a different mechanic. Check the mechanics files at the top of this page, ask anyone you know who might be into cars for a reputable, competent shop. Best to avoid chain auto repair businesses, instead find a locally owned small independent shop…

Good luck, and report back with whatever you find. Also, best to check your coolant level when the engine is cold, and top it up before driving. For now, you might need to do that every day until you solve the problem. What you don’t want to do is run the engine when the cooling system is empty. Then you would have to get rid of the car.