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E30 85 325e Overheating

August 25, 2009

Q
My 1985 325e overheats. I replaced the thermostat and flushed the engine and it still overheats. Is there an easy way to check and see if the fan is working?
Mike

A
Is your 325e overheating when in stop-and-go driving and idling, or when you are driving at highway speeds? If it’s OK at highway speeds and has trouble at slow speeds and idle, I would suspect a worn engine fan clutch and/or a non-functioning auxiliary fan. To test the auxiliary fan, pull the wires from the two temperature switches on the driver side of the radiator. With the engine running or the ignition on; connect the two wires from one of the switches together. The fan should come on at either the low or the high speed. Now, disconnect those and connect the other two wires. The fan should now come on at the other speed (high or low).

If the fan works on both speeds, I would suggest new temp switches. We also carry lower temp switches which will turn the fan on sooner.

If the fan only works on high speed, you need a new low speed resistor for the fan.

If the fan does not work at all, check for 12 volts at the green & black wire for the temp switches (from the green/black wire to ground), with the ignition on. If there is 12 volts, the fan is bad. If there is not 12 volts, the relays or the fuses may be bad.

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Categories → 3 Series 84-91 - E30

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