TheSamba.com :: View topic - oil pressure sending unit-idiot light

Wed Oct 28, 2009 10:15 am

What gives? I've replaced the idiot light sending unit twice. Both with a new unit. When I turn my ignition on the light doesnt light up. If I ground the wire, the light comes on. If I turn the ignition off and on a few times the light comes on, sometimes. I really dont trust this thing to light off if I lose oil pressure. So I'm going on my 3rd sender now. Are these senders just junk?
thanks for the help

Wed Oct 28, 2009 10:40 am

Use thread tape to install the sender?
If so the sender isn't grounding properly.
It has to be for the light to work when no pressure is present.

You have it wired correctly I assume.

Key on hot wire to one side of light, other side to sender.

Wed Oct 28, 2009 10:46 am

yea , used tape. Thats what I was thinking, that it could prevent it from grounding. So how will I keep it from leaking? When I get home I'll check the sender with a meter and see if it has continuity....from the terminal to the body of the sender. Sender #1 had no continuity. I'm just irritated , alot of the stuff just seems like chinese junk these days.

Wed Oct 28, 2009 12:00 pm

The sender threads are probably brass and you're screwing it into a non- ferrous case. The metals are soft enough to seal without additional sealant.

Fri Oct 30, 2009 9:01 pm

Could a small copper seal/washer do the trick to keep it dry and help give contact?

Sat Oct 31, 2009 8:06 am

I use plain old pipe dope (plumbing supply) it seals but also allows metal to metal contact of threads, so sender grounds....

Teflon tape is not a sealer, its intent is to lubricate threads so you can gronk down tighter on it and get better mechanical seal, only problem in alloy case you will crack case before you get it tight enough ... Also most new pressure switches I have gotten lately has a factory applies sealer already on thread.... Look for a bluish or redish coating on thread area.... If sender has it, you don't need additional sealers in most cases (assuming threads in block are good)...

http://en.wikipedia.org/wiki/Thread_seal_tape

Dale