Technical Electronic oil pressure sender/guage, problem

Have another problem I sure could use the HAMB help on.

Have a electronic Stewart-Warner vintage looking oil pressure (0-80) guage, bought new in the '90's. 5-6 years ago, mounted the guage, and a (suposidly) SW electronic oil pressure sender bought new at Advanced.

Last week I was "priming" the bone stock engine, 30w ZR-1 Valvoline oil, with a common (well used) 3/8" electic dill motor, and a "priming tool" I made out of a old distrubitor. Dedcided to turn the ignition witch on and see now much oil pressure the drill was churning through the motor. The guage rose ''normally" when the drill was started, however the guage pointer went clear past 80, and "hit the peg"!

Now, I am more familiar with a mechanical oil and temp guage systems. But this time used electronic, because a single wire was easier to hide.

So, where do I start troublshooting? Those electronic sending units now are in the $70 range! Just can't run down and buy another one "just to see"!

Thanks for your help!

 

Sounds like a mismatched gauge and oil pressure sensor. Photos or part numbers would help.

 

Do you know the part number of the sender you bought? And the gauge?

do you have a digital voltmeter? and know how to use it?

 

Is that 'bone stock engine' a fresh rebuild? Cold 30W oil on a tight clearance motor can have some pretty high pressure numbers.
Or there could be a mismatch between the new sender and the gauge.

I think I would start out with some 10W 30 oil and see what the gauge reads.

 

Try pulling the sender and hooking it up to a regulated air supply fitted with an acceptable/good pressure gauge and compare apples. The sender won't care if it's an air or oil pressure signal.

 

Ah,,,,, I was wondering "if" the sender had to be matched to the guage, like the gas tank float sender and guage. I'm more of a "mechanical" guage units, I understand them.

Squirrel. Part #'s!? it was in the '90's when I bought the oil pressure guage. It was tucked away in the drawer until 5-6 years ago. That is when I took it out, mounted it, and bought the sending unit at that time from Advanced and wired it up. There is no way I could find any part #'s!

Wonder, if I bought a new(er) SW guage,,,,, might get "lucky" in matching?

Son In Law, is looking to see if he has an old mechanical oil pressure guage laying in his junk drawer. I'll start there, with a known pressure.

31, good idea. Glad you thought of that. BTW, which end of "Down Under" are you loacted? I sold a Ply Vert to a guy who lives clear on the bottom in the middle.

Gene, the motor has been run before a short while after it's been re-built. It's been 10 years since I have last run it.

Thanks for the ideas.

 

Tight clearances and dead cold oil , it will peg the gauge . I just did it priming my fresh 289 for the Tiger . My 32 will still maintain 80 psi rolling down the highway and the engine is 30 years old .

 

Use the mechanical gauge first to determine actual oil pressure. Then switch in the sender unit and measure resistance between sender and ground while spinning the disty shaft. Take the resistance measured and use the same resistor value in place of sender. If the gauge still reads different than the mechanical gauge then sender is not correct for the gauge.