Temp Gauge/sender questions. - The Unofficial BMW M5 Messageboard (m5board.com)

GoneAgain · 25th September 2005, 10:26

Hi all,

Just bought an 89 M5, looks in decent condition but with a couple of niggles.

Firstly, the oil temp gauge doesn't work. Is the sender for this mounted at the oil filter housing? And is this sender connected to the ECU, because the car runs great and if this sender was faulty and conected to the ECU I would expect something else to be amiss!

Secondly, the water temp comes up to the middle of the gauge, but after a quick burst up to 170-180kmh the needle becomes a bit erratic, fluctuating from top of the blue to about 1/3 of the gauge. From what I've been able to discover there seems to be at least 3 coolant temp sensors/switches! Two next to each other on the radiaor line and another near the thermostat housing. which one feeds the gauge? And does it feed the gauge only. I'm not getting any warning messages about coolant temp or level so again , is the ECU hooked up to a different sensor?

Cheers

T

Alan Archer · 25th September 2005, 14:24

Yes, the oil temp sensor is on the housing,

as for erratic temperature readings...I would start by believing the gauge
and checking out why the coolant temperature is fluctuating so much...

Could be a jammed viscous fan or broken thermostat,
worse still, the thermostat might be missing or removed to prevent serious overheating showing up.

M5's are like most traditional BMW's in that once that temp gauge hits the middle it should stay there forever barring nuclear wars etc.

Regards,

Alan.

GoneAgain · 5th October 2005, 19:52

Cheers Alan,

Water temp gauge has settled down. Just cleaned up the sender connections, now it stays bolt upright once it gets warmed up. Viscouse coupling all seems ok and I'm sure the thermostat is fine, heater is great after only a couple of minutes so it's not stuck open, and been stuck in traffic a few times & no overheating, so not stuck closed either!

Oil temp is another matter. It moves very slightly when I turn the key to position 2, but is in the negative virtually all the time.

I took the gauges out & all looks ok, but stamped on the back of the gauge is "fuel econ".

I'm thinking the cluster may have been changed, but M5 dials inserted!?

The check control routine doesn't work either, and I can't see anything that looks like the code chip, what do they look like? Are they on the exterior of the cluster?
I'm also unable to change the language on the dot matrix (although this is working fine).
I've done a search & gone through all the OBC Test/reset reoutines. The only launguage is LA-G; But I can cycle through the languages with the check stalk pressed.

I'm thinking about getting hold of a UK OBC and instrument cluster, do you think this sounds a reasonable course of action?

Thanks in advance.

Terry