Talking about a 1992 2.2L cavy. While I'm driving, weather it be on the highway or not, my temperature fluctuates from 120 to 140 degrees F. This would be acceptable at an idle, but this is happening at 65mph. The car takes normal time to get up to temperature, then once it is there, it will take about 3 minutes to get up to 140, then it drops down to 120 in about 3 seconds, and repeats.
The thermostat was replaced about 4 months ago, and just now I have replaced the radiator, (it was leaking), the water pump (it was squeaking), and the cooling fan relay (I didn't think the fan was coming on at the right time). Note: if you unplug the wire from the thermostat housing, the cooling fan does come on and the check engine light comes on, but with the thermostat plugged in, the fan doesn't seem to come on when it is supposed to.
Is this just a bad thermostat? Is the temp sending unit bad? If so, can you help me locate the temperature sending unit?
The temp sending unit should be located on the thermostat housing, Theirs a wiring harness sticking out of it.Has youre cooling system been flushed as well?. Since the new rad and thermostat?. Does youre car also need coolant to be added?. You could still have air bubbles in the cooling system.
Good Luck
Keep Us updated.
Keep in mind ur thermostat should be a 180 or 195 when the fan would actually engage or higher.Also when doing 65 mph the cool air reduces the heat the radiator has and would cause a fluctuation in the temperature!As long as ur system was properly bleed of air and the temp needle does not either go all the way to hot immeditiatly or stay at the bottom cold the coolant sender should be fine.If u want a piece of mind u can change the temp sending unit which should be at the thermostat housing and most stores like auto zone or advance auto carry those items in stock most of the time.My fan does not come on until about 200* and yes the temps on highway driving do affect ur gauge even tho my car has dummy lights and no gauge.I would not worry over it as long as the car does not over heat or irractic gauge behavior like stated above.Hope this helps u out.
William Rillo wrote: the fan doesn't seem to come on when it is supposed to.
The coolant fan should come ON at 106 deg C/223 deg F and go OFF at 99 deg C/210 deg F
When you disconnected the wire from the thermostat housing you were actually disconnecting the temp gauge sender and the Engine Coolant Sensor.
These are both combined in the screw in unit the wires were connected to.
The ECM detected that the ECT was not working, set DTC 14 and turned the fan on constantly, as it is designed to do.
This is just a little more info to the advice others have already given.
Hope it helps
Alont
