M42 temp gauge creeping up just past mid pt

[jdt10768]

on my 1991 318is with fairly new radiator within past 6 months, I've noticed the temp gauge creeping just past 12:00 (normally it stays at 12 noon), and yesterday on a 2 hour highway trip at 75-80 mph, it crept up higher, almost to the next mark (3/4), but never past. I stopped and checked coolant levels twice just to make sure. No indication of what might be causing the temp to rise, and it was running fine. It may just be the gauge flaking out, not sure. Any ideas? coolant sensor? cluster flaking (flucking) out?

[bmwman91]

Could be a dying thermostat or failing pump. Any idea how old those are?

[jdt10768]

Could be a dying thermostat or failing pump. Any idea how old those are?

I am not sure. Bought car ~ a year ago. Thermostat sounds like a good place to start. Water pump, no idea of its history. How tough to replace water pump? will start a search

[cferb]

Thermostats are cheap and easy, I'd start there. Just did that on my Subaru for the same issue.

[cabin]

If youre going through the trouble to replace the thermostat, you might as well replace the pump too, its right there. New pumps for the m42 arent exactly expensive either.

[jdt10768]

replaced water pump and thermostat, and it is still creeping a bit past mid-point. One thing I noticed this morning while driving to work: when the temp gauge crept a bit past normal (12:00), I tapped the cluster, and it dropped back to 12:00 - so maybe a bad temp sender unit now?!

[bmwman91]

Interesting. If tapping the cluster "fixed" it then it might just be a corroded ground nut on the gauge, or one of the many other little electrical issues that the clusters can have. You can try pulling the cluster and cleaning the ground nut / pad for the temp gauge.

[jdt10768]

Interesting. If tapping the cluster "fixed" it then it might just be a corroded ground nut on the gauge, or one of the many other little electrical issues that the clusters can have. You can try pulling the cluster and cleaning the ground nut / pad for the temp gauge.

I will do that. I have a set of odometer gears, and a crack free dash that need to go in at some point. Wife asked me this morning: When are you going to get that dash out of our family room? I just need a free weekend to get it done! I'll report back . . .

[jntar]

Pull the cluster, take the back off, then remove the nut that holds the temp gauge in. Hey some high count sand paper and sand the metal area the post goes through, sand the washer as well. Replace amd will be as good as new.