Question1986 crysler lebaron turbo 2.2l . the car overheats when just sitting in idle or at a stop. the cooling fan does not come on all the time and when it does the engine is real hot and the fan runs for only a few seconds. I have checked the fan and it works. I changed the relay switch still no dice. could it be the cooling fan switch and where exactly is it. in the 1986 2.2 turbo. Is there a test.
AnswerHi Gerald,
The relay is controlled by the engine controller and the engine controller gets its information about the temperature of the coolant from the temperature sensor located on the side of the thermostat housing (2-wire plug)which is located just below and between the #3 and #4 spark plugs.
The reason for the fan not coming on soon enough could be either that the sensor is out of calibration or that there is air trapped in the thermostat housing so that the sensor is not being properly bathed in coolant. To test it,
the resistance across the two pins of the sensor should be 7,000 to 13,000 ohms at 70F and 700 to 1,000 ohms at 200F, the normal operating temp of the engine.
So check that out. But before concluding the sensor is bad, you need to verify that there is no air in the housing.
Then to properly avoid air getting in the thermostat housing you have to drain and refill the system following a specific procedure. Before I tell you about that though, you might try very slowly removing the plug on the top of the thermostat housing (8 mm Allen head wrench) and observing whether when you gradually lift it out of its hole the coolant is right up to the top of the opening. If not, then add coolant through the opening until it fills to the top of the housing and then replace the plug. Put some anti-seize compound on the threads of the plug.
If you have drained the radiator in the recent past, you may have air in the thermostat housing or the radiator core circuit. The best thing to do would be to partially drain the system and follow the instructions for refilling:
There is a plug in the top of the thermostat
housing (8mm allen head) that has to be considered when you are
dealing with the cooling system or you will trap air in the housing or
the heater. Here is the way to do drain and refill:
Start the engine and put the heater control slider in the Heat
position (this opens the water line to the heater). (A/C should be off
of course)
Shut off the engine
Open the radiator drain valve and watch to see that the water drains
first from the coolant recovery bottle. Then remove the radiator cap
and let about another quart or so drain out. (You can collect the
coolant in a pan for reuse if you choose).
Then remove the plug from the top of the thermostat housing and let
the water drain out of that housing, use a flashlight to observe level
(you don't have to drain any further if you are just trying to remove
trapped air, otherwise complete draining).
Close the drain.
Start refilling thru the radiator cap opening
When the coolant level rises into the thermostat housing and up to the
top of the plug hole, stop filling and put in the plug (put some
never-seize compound on the plug threads).
Continue filling thru the radiator cap opening until radiator is full.
Put on radiator cap.
Fill the coolant recovery bottle to the "max" line on the bottle.
In theory you will have now a air free cooling system. At least if
there is any trapped air it will work its way out more quickly if you
follow this procedure exactly. This may lower your operating
temperature and also eliminate the intial rapid rise of the gauge.
Roland
