Where's My Engine Temp Sensor?

[flixbiz]

My 1986 SL radiator fan doesn't work and I get cool "heat" at highway speed. My search of this board indicates to me that the culprit may be a faulty engine temp. sensor. Since it's only about $30, I don't mind buying one on spec and installing it.

The only problem - Where is it?

[y2kimmel]

Many cars have a separate sensor for the engine temp instrumentation (the gauge in your dash cluster) and the sensor for the engine computer.

Is your temperature reading low on the gauge? Is your car taking a LONG time to get to where it normally operates? This, combined with your comment about cool heat, leads me to believe that your problem could be a thermostat rather than a sensor problem. A thermostat stuck open would cause cool heat.

Troy
1995 E420
Olney, MD

[flixbiz]

Dash temp gauge reads normal and doesn't take unsually long to get there. Heat is fine at "city" speed, blows cool at hwy speed. I've never seen the radiator fan operate, even when idling for long periods. That can't be normal.

I don't know, does a 1986 SL have similar computerization to a 1995 E?

[y2kimmel]

I know that when I bought my E420, the radiator fans were inop. as well. It turned out that there's a power resistor that had a corroded contact (the resistor allows low speed fan operation). I replaced the resistor, took about 2 hours because the damn thing is buried in the engine bay, like everything on a M119 engine, and fans now work fine.

I doubt that your radiator fans will be running in winter - the main fan should do the job fine until things heat up.

Troy
1995 E420

[Ali Al-Chalabi]

If the cool heat at highway speeds is due to low coolant temp, then you will need a new thermostat. What temperature does the engine run at on the highway? It should be at at least 80C or higher.