560SL overheating

My '87 560SL overheats. The electric cooling fan doesn't come on. I have replaced the temp switch on top of the thermostat housing, with no effect. Temporarily, I've jumped the 2-pin connector on the switch so the fan runs whenever the car is on. Where is the relay for the fan, and what else could be keeping it from activating? Thanks...Kevin

Well, if you jumped the two wires and the fan came on, all things from that point on are in order. Is your gauge reading accurately?

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I assume the gauge is working properly. When it's cool outside, it reads normally. If it's hot and/or I'm sitting in traffic, the gauge will go into the red zone (slowly,) but come down after I start moving again--all while the electric fan sits idle (unless jumped.) It never runs as cool as other SL's I've had.

There are more than one switch on the thermostat housing. Are you sure that you replaced the correct one. I have seen radiators clog up on these and the termostat. The other thing though not common to fail is the fan clutch. When the car is hot the fan clucth should engage the fan.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Yesterday the car appeared to run somewhat hot (100 C according to the dash gauge,) but the temperature in the reservoir was 80 C. It had been running for about 45 minutes, the reservoir was fully pressurized, and I assume the temperature reading was accurate. Of course, the temp switch was open-circuit, and the fan was off. Can the gauge be calibrated, or could the sending unit be reading improperly? Which swich sends to the gauge? I'm relieved, but still annoyed. Thanks...Kevin

There is a single pole switch that sends the variable resistance to the gauge. I have the specific resistances that corelate to specific temps on the gauge. I'll look around at work and see if I can dig them up.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM