Fan on all the time

Post Mon Jun 06, 2005 8:20 am

What's the most likely reason... temp stays about 1/3 all the time... fan starts up from cold... sensor maybe? where abouts are they?

Post Mon Jun 06, 2005 8:23 am

What engine u got mate

Post Mon Jun 06, 2005 8:36 am

sorry M20

Post Mon Jun 06, 2005 9:01 am

Just been through tis and cant find switch but can tell u that if the viscus is workin properly then it should'nt cut in till 90 deg mayby the cupling clutch is shagged

Post Mon Jun 06, 2005 9:02 am

sounds like the thermostatic coupling (aka clutch) is seized. New ones are 100 quid from BMW. Cheaper from Euro Car Parts. I don't think there is a sensor, its just some sort of metal or fluid expansion in the coupling itself that engages the fan. They ususally fail by not engaging, so maybe this fault is fixable if its just corrosion or dirt - unless some previous owner jammed it to avoid paying out for a new unit when the motor started overheating!

The unit is quite aesthetically pleasing, to my eyes. I keep meaning to clean my old one up and use it as a paperweight or summat.

Sad or what?

Post Mon Jun 06, 2005 9:04 am

That'll b y i could'nt find the switch on tis

Post Mon Jun 06, 2005 10:22 am

If you are talking about the viscous fan then it will run all the time the engine is running. It will start to turn as soon as the engine does.
When the viscous fan starts to fail, it will not keep the engine cool enough. 1/3 on the temp guage seems fine, about what mine used to stay at.

An auxiliary electric fan, like found on cars with aircon, will cut in at 90deg and 99deg if its a two speed. If you have an aux fan then maybe the thermo switch is faulty.

Post Mon Jun 06, 2005 10:46 am

a good idea that the fan couplins had it is ,try and spin it when the engines off if it spins freely and doesnt stop fast then its gone

if it spins with alot of resistance then it should be ok..

somtimes the more u spin it the losser it gets

spin it both ways too .

Post Mon Jun 06, 2005 11:15 am

is it making a loud noise all the time?

If this is the case then it might not be a faulty viscous.

This can happen if the rad is very dirty and not dissipating enough heat quickly. I had this problem on my m5 and a good clean of the rad now sees the visous nice and quiet.

Post Mon Jun 06, 2005 11:40 am

If when you drive up to highish revs and it sounds like an old Volvo, with a massive whirring noise, then the viscous is locked on!

Post Mon Jun 06, 2005 11:42 am

davetouring wrote:If when you drive up to highish revs and it sounds like an old Volvo, with a massive whirring noise, then the viscous is locked on!

LMAO that's it...

Post Mon Jun 06, 2005 11:43 am

New viscous time!

My old 320i did this for a while. Although occasionally it'd 'let go' it grab again a while later.

I resolved the problem by fitting a 2.5 engine, there may however be an easier way!

Post Mon Jun 06, 2005 12:48 pm

warning though, my m535 had a failing viscous and ran too warm in traffic, replaced it with a cheap ECP part and from then on the bloody thing was on practically all the time, like a volvo as dave said. i was ok from cold but once i'd got into one traffic jam it would take miles of dual carrigeway to get it to go off again, my 528i never did that. rad was near new.

pi$$ed me off so much i put an electric one in instead!