Electric Cooling Fan Failed... - The Unofficial BMW M5 Messageboard (m5board.com)

DaveW · 29th June 2009, 15:49

Having just read a similar post on ditching the viscous fan in favour of an all electric solution, my thread seems to be quite timely.

Having noticed an increase in Viscous Fan noise and reduced output from the A/C on my Bi-Turbo - a little investigation revealed a stone had wedged itself behind one of the blades of the electric cooling fan preventing it from turning.

With stone removed, fan won't run - no fuses in the engine bay box appear to be blown so anyone got any ideas? Do the motors burn out quickly or would the high and low speed relays suffer first? Or perhaps I've not found the right fuse location...

All help greatfully received!

Thanks,

Dave.

1day · 29th June 2009, 16:42

depends how much current the fan was allowed to draw before the fuse kicked in.

if the rating of the relay / fuse is close to the max rating of the fan then the chances are the fan motor will have burned a "ditch" in the electric coil surface (like a flat spot in a tyre).

if all else fails then try power the fan directly from a spare battery? (although I'm no auto electrician, I've seen it done).

If it's thermostatically controlled, it could also be a temp sensing problem?

DaveW · 29th June 2009, 17:23

The only diagnostic I've successfully completed is to prove the radiator thermo switch is working, so sadly it's not that.

The fragile fan coil theory might well be right - I'll bridge the relay outputs to see if it does jump into life before I tear the whole front end down to get at the fan. Anyone know of a replacement in any shed/garage anywhere?

Thanks,

Dave.

davidoli · 29th June 2009, 21:33

What's the part number Dave ? I'm sure I've got one ......

D

DaveW · 29th June 2009, 21:56

Hi Dave,

Well, if you trust Real OEM to get it right first time, the part number is 64541392913 listed at a whopping $595! but to find out for sure I'll have to take it off. It has curved blades if that helps?

Thanks,

Dave.

davidoli · 29th June 2009, 23:28

Don't worry Dave , I'm sure that I've got one .

£20 + £10 p&p ......sound fair ?

D

DaveW · 30th June 2009, 00:32

Blimey, more than fair - I'll take it!

PM to follow with my address details.

Thanks,

Dave

M5 GOR · 30th June 2009, 00:50

If the fan was jammed it is possible that you have burnt out the low speed resistor as all the current goes through that at low speed and by-passes it at high speed. If you can "short" out the switch on the side of the radiator to bring on the fan at full speed it should show you if it's the fan or the resistor.
I've found that the resistor sometimes can go before the fuse does so it kinda sends you off in the wrong direction!