The temperature gauge on my tin top has started moving. I know this wouldn't be a cause for concern for most people, but it's a BMW and it's stayed at 12 o'clock for the last 20,000 miles, in summer or winter.

Now it's all over the shop. I strongly suspect the water pump is shagged.

Temp is fine when on the move, but in traffic or at idle it goes sky high. Then when I start moving again it drops back down to normal. The BM has a fan fixed to the engine, so that still spins. The water system is full with no leaks.

Water pump?

It's an arse of a job and my local garage can't fit me in until next week!

Mike

Sounds like a circulation problem

If it isn't an air lock it could be the thermostat istr BMW thermostats open under flow pressure as well as being temperture operated.

Of course the above assumes the fan coupling is cutting in normally.

[Edited on 29/5/07 by britishtrident]

What model of BMW is it? I have heard of viscous fans not working correctly on some BMWs.

sounds more likely thermostat as british trident suggests.

for me its just a fan issue.

you only need a fan when not moving sow dad easy not?
If the thermostat would be faulty it would be stuck open.

if the pump is faulty it would take a hell of a time to get at normal temp.

sow for me deff the fan.

manye times they are ditched for electric ones on beamers.

Tks

bimmer viscous fans are prone to failure, my money is on that.

Another vote for the viscous fan.

Glad to see people agree with me about the fan problem. I know it looks like a simple fan but they do stop working.

easy to test the fan -- apart from the obvious (see if it suck & blows) leave the engine to idle then check the raddiator water outlet temperature