I hate to do it but, another temp gauge post

[944Spec_bound]

There are so many overheating and temp related posts that I'm sure there's an answer already posted, I'm just too tired and/or don't have the patience to read them all.
So my apologies, but here goes another.

It's NOT actually overheating, temp is 170 max by infrared thermo and fans are cycling normally. But gauge jumps to extreme right and fluctuates when hitting bumps, so I'm pretty sure it's a ground or connection issue. I just don't know what else to check.

- Replaced thermofan switch and thermostat, both are now 160 degree.
- Flushed radiator.
- Replaced temp sending unit.
- Re-soldered connector at sending unit.
- Bled air out.
- Cleaned all ground points.
- Replaced all ground wire ends with gold plated type.
- Replaced fuses and cleaned fuse cradles.
- Stripped the majority on the interior down to the metal and traced wiring looking for corrosion or shorts.

It's actually worse now! Aagghh!
Bright side...at least I got my Stage 1 weight reduction done.

[Outback Porsche]

When you were cleaning grounds, did you remember the ground point behind the fuse box?

Jeff

[djnolan]

sounds like the engine side is covered. when you cleaned the grounds you got them good and tight? there isn't one you mght have missed?

If not, I would suspect the gauge or something in the dash. I have a 85.5 and could envision something loose in the dash cluster. I don't know the early model dash, though. is it just the temp gauge that is flaky? do any others flicker as well? did it ever work correctly? does it sit at the bottom when cold? if you disconnect the fan for a bit does gauge go to hot? I had to bend the needle on mine to calibrate it.

[944Spec_bound]

Originally Posted by Outback Porsche

When you were cleaning grounds, did you remember the ground point behind the fuse box?

Jeff

Ya, I spent the most time on the one behind the fuse box, under the dash. If I had to do it again, I would have taken the drivers seat out first instead of breaking my back over the threshold. I eventually took it out when I had start tracing wires I'd pulled loose by moving the fuse boxes around.

[944Spec_bound]

Originally Posted by djnolan

sounds like the engine side is covered. when you cleaned the grounds you got them good and tight? there isn't one you mght have missed?

If not, I would suspect the gauge or something in the dash. I have a 85.5 and could envision something loose in the dash cluster. I don't know the early model dash, though. is it just the temp gauge that is flaky? do any others flicker as well? did it ever work correctly? does it sit at the bottom when cold? if you disconnect the fan for a bit does gauge go to hot? I had to bend the needle on mine to calibrate it.

I'm 99% sure I got all the grounds, according to the diagrams on Clarks and Pelican. I double checked tightness and tested resistance on my connectors.

Hmmm...the fuel guage is off, I ran out at 1/4 tank. The instrument lights are dim but don't flicker. Temp gauge does bottom out when cold though.
I think the cluster is coming out next, you talked me into it.

[Outback Porsche]

The guage could be faulty.

You can always check the operation of the guage using the procedure from clarks;

http://www.clarks-garage.com/shop-manual/elect-19.htm#coolant

Unfortunately, this procedure doesn't exclude a wiring fault, but it's not too hard to check the wiring for continuity.

[944Spec_bound]

I don't know how I missed that page on Clark's site, thanks for the link.
I don't have a test potentiometer, but I'll see what I can come up with.