TECH: 1997 Chrysler Concorde 3.5 Overheating

I have a 1997 Chrysler Concorde with a 3.5 V6 and 120000 miles that recently developed an engine overheating problem. When I was driving on the freeway, the temp gauge went to hot and the temp warning light went on. I stopped at a gas station and bought some anti-freeze. I filled up the reservoir tank and started driving again on the freeway. It seemed to do fine for about five minutes on the freeway, and then the same thing happened - gauge went to hot/warning light. The weird thing was that there were no anti-freeze leaks. But, I just noticed that trans fluid has started leaking from the lower radiator trans lines. So, the reservoir cap and the thermostat will be easy to replace, so that is covered. How can you tell if a waterpump is bad on this model? The trans fluid leak at the radiator makes me think it might be a radiator problem. Another clue was a few months before the overheating problem, the heater would intermittently blow cold air. I wanted to see if anyone had any suggestions before I dived into this one. Thanks!

Reply to
fredsmythson
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At that many miles, I would not only replace the thermostat, but flush out the whole cooling system and replace with the proper mixture of antifreeze and water. This will solve your overheating problem along with the system blowing cold air. As for your leaking transmission fluid by the lower radiator line, I would check and tighten (slightly) the bolt that connects to the radiator. Be careful not to overtighten. If this doesn't work, it may be time to replace the rubber seal or washer thats inside where the bolt is. This should take care of your leaky tranny fluid.

Good Luck,

Fwed

Reply to
fweddybear

The water pump on the 3.5 is driven by the timing belt. At 120k, its due for a timing belt, a new water pump, new thermostat, new radiator hoses, and a cooling system flush and fresh coolant if it hasn't been done before.

Its possible that the water pump impeller is slipping on its shaft and not circulating coolant properly. Its possible that the thermostat is stuck closed or partly closed. Its even possible that the radiator is partially plugged. I'm betting ont he water pump.

Also, once one of these engines gets low on coolant, its MANDATORY that you open the air bleeder (on the thermostat housing) while filling with fresh coolant in order to clear all the air pockets out of the cylinder heads. The first-generation 3.5 is pretty tough and will take a lot of abuse, but it does have aluminum heads and they WILL warp if you continue to drive it with trapped air in the cooling system.

The transmission fluid leak is almost certainly unrelated to the engine overheating. These cars are known to sometimes develop fluid leaks at those hoses, and the hoses should be replaced when leaking is found (assuming its not just a loose clamp at the point where the rubber hose attaches to the radiator).

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Reply to
Steve

Losing coolant without leaks is sometimes caused by a blown head gasket. If you've got a blown head gasket, you may want to avoid, rather than complete, the necessary timing belt maintenance depending on your financial plans. You might want to think about figuring that out first.

Reply to
Joe

I first poured coolant in the themostat housing to fill up the engine block and then filled up the recover tank. I installed a new thermostat and put everything back together. I started it up and waited for the engine to get to operating temperature. Then I opened the air bleeder value at the thermostat housing to get the air bubbles out of the cooling system. I took it out for a five mile drive on the city roads and the freeway. Seemed to be running cooler than before. Concorde rides again! First time I've seen a thermostat go bad... Thanks for your help!

Reply to
fredsmythson

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