Engine too cool?!

[molesz]

A few weeks ago my temp. gauge got funky. It simply wont go up to the middle (norm engine temp.). I have changed the thermostat (92C) and the fan clutch and everything looked fine ... suddenly the temp gauge dropped to say 85C and stay there. Next day started up the engine (M50B20) everything again looked ok. ... than again, temp gauge dropped down to 85C.
Damn, everybody got problem with owerheating ... my baby just wont heat up properly! HELP?

[BigD]

Your thermostat is stuck open.

[632 Regal]

yep, got a bad thermostat. Curious, is it a BMW stat or aftermarket?

[Julius]

I've got the same problem. I'm going to have it looked into and replaced.

[molesz]

I got one aftermarket 87C in it when all started, after I put in an original WAHLER BMW thermostat 88C, same thing, finally I bought one 92C WAHLER BMW (Made in Germany) and guess what, same thing again. At first the temp gauge goes up to nominated thermostat temp. then goes cold. The last two thermostats done that within 60 miles.
Any suggestions?

[BigD]

Could be a gimpy temp sender. There are two on the thermostat housing, the coolant temp sensor which the DME uses for it's own purposes, and another which is for the gauge. Might as well replace both, not expensive.

[molesz]

Its an M50 engine and the temp sender is not on the thermostat housing. Worth trying, Ill check that next.

[BigD]

Hmm, yeah I mostly know the M30 and S38 but that's a logical place for it to be so I didn't look it up.

But yeah, just get a new one. Easy job and it's one less thing to go wrong in the future.