Why Is My Car Engine Overheating?

Think you might have a head gasket problem? Watch this short video and see.

Reader Question

Dear sir:

Please help if you can. I have a 2000 Dodge Durango (5.9L) bought in November 2007. In late January 2008 we moved 700 miles. A week later the truck overheated for the first time. When we checked the radiator it was bone dry. After it cooled down we filled it up with radiator fluid. It was fine for a couple of months.

On March 20th it overheated again, this time radiator fluid leaked from what looked like the radiator itself. After getting a quote of $650 for labor and parts to replace the radiator and the theromostat, I tried to see what I could do to fix it.

I replaced the thermostat and thermostat gasket. My fiance and I still drove it for two weeks around town (which we could only drive it one mile before it overheated again), but it was still leaking radiator fluid. After that we put in heavy duty Barr Leak and drove it without the heater for a week in town, it is not leaking anymore, but it is still overheating.

As long as we have the heater on full blast, it will stay within normal temperature. I still do not know what is wrong that it would overheat. There is a strange noise coming from one side of the engine that sounds like it is missing, but my finace says that it sounds like the fan belt is loose.

The only thing I can think of is the head gasket, but I do not want to spend $150 if it is something else, or if there is something I can do that is cheaper until I can find a different vehicle.

Any help will be appreciated. Thank you.

Sincerely yours,
Andrew

Hey there Andrew,

First things first, get a cooling system pressure test done to determine if you still have a leak or not…and if you do, where is it? This test will also rule out a very expensive head gasket issue, which I don’t think you have with the information you have given. To me, I would say you still have a coolant leak, or you have a radiator that is restricted with rust and junk at the bottom, and you need a new radiator.

1. A restriction in a radiator will usually cause the engine to overheat when at high speeds like on the freeway. You can sometimes feel the top and bottom of the radiator when the engine is at normal operating temperature and feel a drastic temperature change from top verses bottom of the radiator if restricted. Flushing will not help either.

2. A bad thermostat will cause the engine to over heat at any speed

3. A bad electric cooling fan motor will usually cause the engine to over heat at slow speeds or while at a stop

4.Turning on the heater just removes the excess heat from the engine and places that heat inside the cab of the vehicle, but since you have hot air coming out of the vents, I would assume you have some coolant inside the radiator…but maybe not enough due to a leak, or not enough coolant circulation due to a restriction.

A fast lube place can do the pressure test, and I would have them listen to your hissing noise as well…..before that becomes a bigger problem. Don’t put this off, and don’t drive this vehicle when overheating…this motor is expensive to replace! This hissing noise is probably due to steam escaping from a hole in the cooling system.

Blessings,
Austin Davis