1985 318i M10 Overheating . Auxiliary fan?

[bwils]

I'm fairly new to bmws but she will get to 3/4 of the way hot just from idle. I noticed the auxiliary fan isn't turnin on so that may be it. All hoses coming from radiator are hot and it blows hot air so it's not the thermostat. And she doesn't leak any antifreeze I just changed the coolant as well. Any thoughts on why the fan isn't turning on??

[oliver.r]

aux fan wouldnt be your problem. the issue would bein your cooling system.
source' i removed the aux fan from my m3, never went over half way in temps.
are you sure its not the t-stat?

[mr.vang]

The aux fan is just a last resort to cool the engine. Your radiator may be too old and losing it's efficiency. If it only overheat during idle, it's most likely your fan clutch is bad.

[bwils]

I'll look into the fan clutch. And I'm not positive about the thermostat I guess I'll replace and it see what happens

[thebutterson]

Search for the newspaper test. I think you basically stick a folded news paper in your fan and when the engine is cold it should stop the fan, but if the engine is hot it should shred the paper. If the engine is only overheating at idle it's most likely the mechanical fan.

[bwils]

It was the thermostat ��. Thanks for all the input though.

[Swanny]

My bet is the fan clutch. Does it get hot and stay there or drops occasionally? Could be an air lock in the system as well.