super eratic oil level gage when cold

[theiceman]

Just reposting as I hijacked another thread ...

I just replaced the sender in my 78sc for the oil tank level . the old one always was active within an eighth of an inch of the red and never went higher. I heard Porsche superceeded it with the 81 and on sender 91164154102 ( mine was 91164154101 ) The new dipstick that goes with it requires you to fill the tank less ( by about a quart ) which is a good thing and prevents smoking on hard cornering from overfilling . My problem is I left the oil at the old level and put the sender in . it immediately read max on the gage after warm up and I had NEVER seen the needle their .. terrific ...
The problem started about a week ago when the oil level started to drop due to some valve cover work and burning etc. Now when I start the car the needle goes up and down like a jackhammer so fast i can't even see the needle. After the car warms up everything is fine , the needle setles down and reads VERY acurately. If I take the wire off after the cold start the needle on the guage immediately pegs. Could I have a bum sender itermitenely losing contact ? I just don't understand why it works when warm.

Anyone have any ideas ?

TIA

ice

[Joe Bob]

The tank isn't full until the engine is warm and thermostat is open. The gauge is only accurate when idling and on even ground and warm....as is the proper way to check the dipstick.....

"I" ignore the gauge....waste of space....

[DonMo]

Erratic guage is a ground problem or wire problem on the sender. Check for loose connection or break in wire. Get someone in the driver seat to tell you when you move the wire.

[theiceman]

Thanks Don That is exactly what I thought. I am thinking I have a bum sender as the wiring I have wiggled and it does not change. I will be able to putt he old sensor back and proove it. I wonder if the acivation of the oil is causing the sensor to break contact and peg out rapidly.