No Oil Pressure Light

[thevojtiseks]

I have just got my engine back in and have started the break in procedure. My cars been apart for many many many years so it's hard to know what works and what does not. The Oil pressure light does not illuminate however and Oil pressure gauge shows nothing. I've measured about 6 Volts at the pressure sender, and I am starting my diagnosis - does 6V sound about right - I'd expected 12ish ??

Any other suggestions of what to look for ?

Thanks !

[Eagledriver]

What year is your car? Mine doesn't have an oil pressure light. Don't know for sure about the sender but I think it just varies the resistance to the engine block (ground). If this is correct then I'd expect 12 volts on the wire to the sender and the meter would read the current through the sender.

-Andy

[thevojtiseks]

it's a 1971....

[Wayne 962]

I think that's right - you can't measure voltage across the sender - only resistance. Check the oil pressure switch first - this is what you use (controls the green light), or simply replace it (they are less than $10).

Don't start the engine until this is fixed!

-Wayne

[thevojtiseks]

Thanks for the advice - especially about not starting the engine until it's fixed....

The voltage I was measuring was at the sender wire to ground - this I had expected to be around the 12v range, but was only 6...

I also noticed nothing seems to move on the Rev counter, I had expected a small flick of the needle at least when I started cranking.....at this stage I'm thinking there may be somthing wrong at the instrument end...Any suggestions are appreciated !

[dtw]

I'm not aware of a oil pressure switch or green light on either of my '72Ts (one with 'S' instruments, or so I thought up until reading this post). Would think this would be similar for a '71, if I am right? Or am I blind? Please advise!!

[thevojtiseks]

I checked the owners manual and it looks like there is a light, however on further reading it appears this is a Handbrake indicator lamp - not a low Oil pressure lamp - thanks for the tip !

Unfortunalty I still have no oil pressure reading when I crank, Even after the alloted 30secs....So if anybody knows what voltage I should be expecting at the sender connector to gound this would really help my diagonosis ?

[dtw]

Sounds like you have some sender issues. Do some more diagnostics on it - hopefully Warren or John can disclose what some good test procedures are. Also check this thread:

No oil pressure?! WTF. Help!

[thevojtiseks]

O.K., so I seem to be getting somwhere - continuity between the guage and the sender seems good, still only around 6V at the sender and gauge....I also traced a green wire which the wiring diagram says is optional - "Oil temp switch for SPM" - does anybody have a clue what the SMP is and what this does - if I disconnect it from the guage the oil pressure seems to work - when I turn on the ignition the needle moves to zero and after cranking it starts to build pressure, after I stop cranking I see the needle drop back to zero.

Thanks