Matt Lane

Hi guys, my oil temp gauge started acting up last summer: it would behave normally, confirming opening of the thermostat to the oil cooler, etc. then suddenly "peg" to a high reported temp above 9:00. After a bit of driving, the needle would just as suddenly drop back to normal. Not a smooth variation in measurement either way, just off and on like a switch.

Problem obviously did not go away. Looked down today after driving a few blocks, and gauge pegged at the absolute top of the range. Pulled over, stopped and then restarted the car. Gauge remained pegged. Drove around a bit since I wasn't worried about any actual overheating, then tapped the gauge glass - needle immediately dropped back to normal operation.

This behaviour leads me to believe it is a problem with the gauge and not the oil temp sender, but would love ideas. How would you proceeed to diagnose?

Thanks in advance for ideas - need to get this fixed this spring before my first DE event...

Best,

Matt

Matt Lane

As a point of clarification, I will of course check contacts at each of the temp sensor and back of gauge, but other than that, is there anything else I should be looking for?

Do the gauges themselves go bad?

M

BobbyT

Hi Matt,

The fact that you tapped the gauge glass and it dropped back to normal points to the gauge itself being the problem. If you have another 993 owner/friend near you, it is not difficult to swap the gauges and see what happens. They are held in place only by the rubber ring around the gauge.

BobbyT

A new gauge head is nearly $500...

AOW162435

Matt,
Contact North Hollywood Speedometer and discuss with them. I have a feeling they've repaired a number of these due to failing solder joints.


Andreas

Dwane

I've got a gauge you can try.
Dwane

Leander

I had exactly the same problem. The gauge was easily fixed for a few bucks. Contact Chris at Bauer Porsche Repair in Oakland and I'm sure he'll tell you how he did it.

Matt Lane

Yeah, the fact that it returned to normal tapping the glass seems to point to a bad connection at the gauge itself, or something internal to the gauge. Will check the connection and see if it helps.

M

Stealth 993

Mine in the C4S did this for a bit. i would tap the glass & it would go back down.

I pulled out the gauge, cleaned up all the contacts, & made sure the needle was not sticking. It only happens once in a while now, but seams to coincide with crap roads. My thought is a bad ground.

Stewart

Don't rule out the temp sensor on the motor itself. It may have been coincidence that tapping the glass dropped the needle back down. My guage needle has started to do the same when I've been using my car for short journeys (long enough for the oil cooler valve to open though) and then seems to clear itself on a properly long journey.