I have an oil temp sensor in my oil pan drain plug. While doing a cam swap I had my oil pan off, and installed a new Fel-Pro gasket. The new gasket doesnt have metal in it like the factory one, so it didnt dawn on me until after the fact that my oil pan wouldnt be grounded anymore - which means my oil temp gauge is no longer working.

Autometer documentation seems to assume that wherever you are mounting the sender will be grounded. Is there anything I can do about this?

I should have drilled/tapped a hole for the sender, as well as an additional one for a ground while I had it off, but alas hindsight is always 20/20.

 

JoeliusZ28:
Don't worry about it. The bolts holding the pan that thread into the block will provide all the electrical ground path you need.

 

Apparently they arent, the gauge doesnt work. I also re-painted the oil pan which probably didnt help.

 

I ran a Stewart-Warner temp sender instead of a drain plug in prehistoric 327 days (heavy wrap of teflon tape on the threads too) without a problem. I know that doesn't help you but it demonstrates it should be possible. There was no metal stiffener in the pan gasket. I suppose if your's suddenly started working I would question the accuracy if the ground was marginal. Perhaps there's enough "meat" on the sensor body to drill and tap for a very short 4-40 or 6-32 machine screw that you could fasten a separate ground wire to.
Good Luck.

 

I just did some reading, there is still the test port above the oil filter as an option for the sender. Ill have to get a new drain plug though, but thats probably what I am going to do.

 

I use that port for a "idiot" switch to ground a Radio Shack 12vdc Piezo buzzer to in case I should lose oil pressure. ISTR that it's 1/4" NPT. I would think a temp reading taken there would be low since the oil would have lost some heat passing through the oil filter.

 

I think the temp sensor in the oil port above the filter would be affected by block metal temperature. Also not sure how deep in the passage you could get the sensor. I have my electric oil temp sensor in the drain plug and it works fine. Scrape the paint off the pan under the pan bolt heads. Block through bolts through pan through drain plug should provide a ground.

 

Accuracy of the gauge isnt critical as long as it is fluctuating appropriately. Im not using this for anything other than an "OK, i should give it a break" sort of gauge, and I dont have any way of logging it anyway.

I just put it in the auxilary port and the gauge is still stuck... could I have fried the gauge?

 

Check the resistance of the sensor. See if it varies with temperature. Put an ice cube on the tip, measure the resistance, put it in ot water and measure resistance. Resistance should change inverse to temp.... high temp = low resistance, low temp = high resistance. If the sensor is OK, check the continuity of the wire from the connector to the gauge. Make sure your gauge is correctly grounded. As I recall, there is a ground wire for the needle mechanism and a ground wire for the light.