1993 Caravan overheats after thermostat replacement

Prof BruJoe · #1 07-02-2005, 08:40 PM

I have a 1993 Caravan and my thermostat was just changed because the engine temp would rise when idle, especially when a/c is running.

The engine has 190,000 miles on it and has been a gem.

If it is not the thermostat, and the engine doesn't smoke or seem to burn oil (2 quarts between change) but the A/C doens't work well now---what could be the problem?

tri-power · #2 07-03-2005, 09:33 AM

most likely the water pump. check the pump for moisture or any small leaks. It's also possible that it's not leaking and that a bearing is bad internally. Also have you checked to make sure that you have a good mix if AF and Water?

B33p3r · #3 07-03-2005, 09:47 AM

It's not totally unusaul to get a brand new "bad" thermostat. No insult intended, but you're sure you installed the thermostat in the right direction. A bad water pump will leave you running low on coolant due to leaks. A bad water pump bearing is pretty easy to hear. If Thermostat,pump, and bearing are all good in you eyes, then it is time to look for a restriction somewhere. Radiator? Maybe a backflush of the system might help?

Prof BruJoe · #4 07-03-2005, 11:29 AM

Thanks for your replies. I am new here, so I appreciate your help.

I didn't put the thermostat on, so that could be an issue. But, I hope the auto shop has some better working knowledge about this than me. If it was installed in reverse, would the temp lower while driving? The temperature always drops once I start driving again. Even if the A/C is running full.

I don't hear any sounds from the waterpump, I don't see any leaks or smell any fluid in the passenger area or the engine area. The heat works well.

I flushed the system 1 1/2 years ago.

Could it be the fans? I've not recognized the sound of it being on. But then I haven't been listening for it.

GTP Dad · #5 07-03-2005, 01:39 PM

Are you sure you got all the air out of the system. An air lock will cause the car to overheat due to not allowing the water to circulate. You can remove the radiator cap and start the car. Once it heats up to a point where the thermostat opens you may see the water level drop. If it does then refill the radiator and this should eliminate the problem. The other item is the fans, if they are not coming on then the van will overheat when sitting still. If the car does not overheat when you drive it then the fans are the problem. Probably a bad sensor or a bad fan relay. The fans can go bad but they can be tested by putting a 12 volt source to the wires on the connector.

cyborghunter1 · #6 06-23-2007, 08:07 PM

My 93 has been experiencing the same problem. I replaced the fan ,radiator,waterpump,thermostat, and A/C compressor. It is still overheating at idle but only with the A/C on. I have come to the conclusion that its not mechanical but electrical. Im sure it has somthing to do with the A/C relay. Im going to get to the bottom of this dilema and i will keep you posted on my progress. By the way 198,000 miles still running strong.

Bear · #7 06-24-2007, 07:16 AM

First question, do the cooling fan/s come on with the AC engaged. Second question, do the fan/s come on as the temp begins to rise above half way on the gauge (AC off). The fans are critical to keeping the temp down and if they fail to operate you will, in most cases go to an overheat condition. There is a relay for the fans and a coolant temp sensor as well. The fans should always operate with AC engaged, and if not I would suspect the relay (unless the fan motor is shot), and as the temp starts to rise above half way on the gauge (AC off) the coolant temp sensor should activate the relay as well.

mrlong · #8 06-29-2007, 11:38 AM

There was an issue about air locks on a dodge site. The thermostat housing is higher than the hose that runs to it so you have to take the plug from the top and fill the housing so it won't be air locked. If it cools when driving are you sure your fan is working? On my 92 the temp sensor for the guage was on the opposite side of the motor than the sensor to start the fan. The head gasket was bad at the end where the guage and it said the motor was hot. The sensor for the fan didn't read from there so it didn't start the fan.

caravandrvr · #9 07-10-2007, 03:42 PM

Quote:

Originally Posted by Prof BruJoe

...The temperature always drops once I start driving again...

Classic sign of fan(s) not working. Idle car until it gets up to temperature, do the fan(s) turn at that point? Do they turn as the car starts to 'overheat'?. If there are 2 fans I believe one should come on as soon as the A/C is turned on.

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