Temp gauge -- works...sometimes. Why?
 

94 C280 with only 51k miles. I've had it for 6 months with no problems -- it is in great shape.

It is pretty cold the last 2-3 weeks (30ish) and I have an odd problem.

Sometimes my temp gauge works and sometimes it doesn't. It will typically be pegged at the bottom. Most of the time at some point in the ride it will suddenly rise up to where it should be. At that point it stays active until the problem reoccurs at a later starting.

1. I have no heater problems (stuck thermostat -- heat works perfectly).
2. I have no engine overheating problems. It never runs hot, and never is at any higher temp than normal when it does decide to work.
3. Coolant is at the proper mix for winter.

Any thoughts or suggestions?

Needle sticking to its stop PEG. Try tapping on the top of the dash next time it doesn't move properly.

Oh, I've banged away. Didn't help.

The dashboard......not your co-workers. :D

Is it seperatly fused? (-not my model or year range-) Intermitant bad contact.?.?
I couldn't find a coolant temp sensor for this car. What kind does it use?

This was my first thought -- a fuse/connection or a sensor.

I'm pretty sure it isn't the gauge and I know the actual thermostat and coolant system is fine.

Just take the sensor wire off and ground it to see if guage responds.

or take an ohm reading of the sensor.

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1M30LAGSC1OH0OZIIL&year=1994&make=MB&model=C-280-001&category=P&part=Water+Temperature+Sender

60C-110 ohm
80C-67 "
100C- 38 "

Where is it located? I am assuming that it is in the very near vicinity of the thermostat housing.

If the gauge shows no reading, and I take the sensor wire off and ground it...are you saying I should see some sort of reading? If I did, then you are saying the sensor is bad?

Thanks,