1992 Plymouth Acclaim gets hot driving

BIGR_USA

MEMBER
1992 PLYMOUTH ACCLAIM
6 CYL
2WD
AUTOMATIC
120,000 MILES

Every time I start the car and drive a short distance the car will gradually warm up. (Normal) The gauge will continue to rise to hot. If I take the car out of gear while moving, and rev the engine a few times the temp gauge will drop fast and rise back to the normal setting. The car temp will now be fine for the rest of the trip. Let it cool down (2 to 4 hours) start it up a it will do the same thing. Every time. I have changed the thermostat (3 times) and the sending unit. Any ideas
thank - you !
ps. First time on this web site, will be GLAD to donate if we can fix this, driving me nuts

5 Replies

DAVE H

MECHANIC
13,383 POSTS

Are there any other symptom's or is it just an erratic gauge?

Check wiring or replace

Temperature Gauge Sending Unit

2.2L TBI & 2.5L TBI & Turbo. On cylinder head, between distributor and front of engine.

2.2L Turbo & 3.0L. On or near thermostat housing.

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Monday, December 8th, 2008 AT 6:33 AM

BIGR_USA

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Dave
Sorry I should of said that I already changed the sending unit. No other symptoms, other than the car getting hot. Then it will cool down and start acting normal. I did see another post about a "Coolant Temperature switch" and "Coolant Temperature Sensor". I do not know what these two things do or if they would have anything to do with my problem. It is a 4 Cylinder engine not 6 as I said above. Thanks !

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Monday, December 8th, 2008 AT 7:09 PM

DAVE H

MECHANIC
13,383 POSTS

Sorry you did put in your first post about sender. My mistake. Maybe the fan is not kicking in when it should. But why it would suddenly start to work when you take it out of gear and rev? At first I thought air in system. Thermo sticking but you replaced it. Try bleeding cooling system. And replacing coolant temp sensor. The sensor is the same as the switch on your car they both start radiator fans going. Try starting the car with hood up and wait till the radiator fan starts. If it doesn't and the temp continues to climb. Waggle the wires on temp sensor and wires on fan motor to see if the fans come on? Of course the actual sensor maybe faulty not the wiring? Even the fan motor could be the fault. But again why suddenly start when changing gear?

Coolant Temperature Sensor (CTS)
The CTS monitors engine coolant temperature. This sensor is mounted in thermostat housing. Coolant temperature information is used by SBEC to slightly enrich or make lean air/fuel mixture, adjust idle speed and control cooling fans as necessary, according to engine temperature. On turbo engines, CTS is also used to control boost levels and spark advance.

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Monday, December 8th, 2008 AT 8:01 PM

BIGR_USA

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5 POSTS

Thanks for the reply and education on what a CTS is and what it does, does not sound like my problem. I will try your other suggestions and let you know. Thanks again

You think it is worth taking to Chrysler dealer and let them "fix it" or would this intermittent problem be a waste of my time and money? As they would not figure it out either but do the same things I already did?

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Tuesday, December 9th, 2008 AT 7:49 PM

DAVE H

MECHANIC
13,383 POSTS

The coolant temp sensor CTS turn's the radiator fan on at a set temperature. If the CTS is not working correctly and turning fan on later when your engine is starting to overheat this could theoretically be what's wrong. But I couldn't understand why it started to cool down (fan come on) when you changed gear? The sensor is a cheap part and may be worth trying before dealer empty's your wallet.? Also the sensor control's idle speed and air/fuel mixture so I think you would notice more gas usage. Your car's high operating temp is 212 °F (100 °C) this is when the fan should come on. Start the car let it idle till the gauge reaches this temp then listen for fan coming on if the temp contiues to rise without fan coming on then the CTS is faulty ?