W123 Temp/Fuel gauge issues - PeachParts Mercedes-Benz Forum

renman · #1 07-19-2012, 03:22 PM

Howdy all. Haven't posted in a long time. Parked our 1984 300 D turbo in 2010 after performing a variety of maintenance items which included valve adjustment, new timing chain installation, new water hoses and thermostat, new fuel filters including tank filter.

Car started right up after almost 16 months and runs great except the instrument panel temp gauge goes right from 0 to 120 c after the car warms up in the garage (5 minutes) and the fuel gauge is pegged over to the full mark and stays there.

No fuses blown. IR temp gun shows the block temp @ 99c and IR temp at the thermostat housing hovers around 89-91c. Pulled the dash wiggled the wires with no change. Just came back in from the car and checking again. Temp and fuel gauge pegged. IR show temp at block & thermostsat housing has dropped to about 65c

What do I need to look for?? is it just soemthing simple like a bad ground?

Thanks.

kerry · #2 07-19-2012, 03:39 PM

Sounds to me as if the wires are shorted to ground.

renman · #3 07-20-2012, 07:23 PM

I got the fuel gauge finally working but not by any brilliant move on my part. I had fiddled with the dash wiring part of the day and couldn't seem to make any headway at all. Finally put everything back in place (the instrument panel) and the temp gauge is stuck at the six oclock position, meaning I have no temperature readout at all whereas before it was climbing all the way to 120c on the gauge. The good is that after carefully stuffing the inst panel back in the hole and pressing firmly on the panel, the fuel gauge started working!! Does this mean the instrument panel not making good ground with the chassis?? Help. Is it possible to install a auxillary temp gauge?
Cliff

E150GT · #4 07-20-2012, 07:38 PM

On advice from a poster here I was told to take leads with alligator clips on each end and clip them from various parts of metal on the back of the instrument cluster to the ground located directly behind the cluster. That solved my problem on my previous car when I put the cluster back in and the gauges all maxed out to the top of the spectrum. Your mileage may vary,,

renman · #5 07-20-2012, 08:09 PM

Quote:

take leads with alligator clips on each end and clip them from various parts of metal on the back of the instrument cluster to the ground located directly behind the cluster. That solved my problem on my previous car when I put the cluster back in and the gauges all maxed out to the top of the spectrum.

Thanks I will do this tomorrow. Now to figure out why the temp gauge isn't cooperating. Possibly the temp sending unit is bad and the auxillary fan is not coming on also.

E150GT · #6 07-20-2012, 08:23 PM

I don't know man. I think the aux fan only comes on when the ac is on or the car gets way hotter than you should be comfortable driving it at. I have noticed some strange things with my temp gauge. It seems it runs closer to 80 when its blazing hot outside, but when its cool it runs almost at 90. I dont know what the deal is there.