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Wednesday, August 23, 2017 11:57:59 PM

Oil pressure sensor

3 months ago
#2468 Quote
All, I've checked my voltage to my oil pressure sensor, and it's 6V. But my gauge shows nothing.  I'm assuming the sensor is baf, but since the sensor seems to be and SOB to change, I'm asking here if I'm missing something. I don't want to waste time and money if I can help it.
3 months ago
#2469 Quote
Turn the key to ignition, ground the terminal on the oil pressure sender, you should see the gauge go to 80+ on the dial.  Failure here says the sender wire to the gauge is open or or there is no 6 Volts at the gauge or the gauge is bad (open or mechanically stuck). If the gauge goes to 80 or more, it is possible the sender case is not grounded.  To test--check the sender terminal for 6 Volts to battery ground and the case for zero Volts to battery ground.  If that test is OK, start the engine and see if there is a pulsing Voltage on the sender terminal. Failure here is either no oil pressure or blocked oil sender passage or an open sender.

Battery ground polarity does not matter, the gauge will read correctly either way if the components are good.

Remember: the oil pressure gauge reads zero with the key off or the engine not running.
3 months ago
#2472 Quote
R.E. - thanks for the reply, I've gotten busy with some other stuff. But as soon as I get a chance I'm going to try this. Thanks again
3 months ago
#2473 Quote
R.E. I get 6 volts when I go from sender post to the + sode of the battery, But 1.7 from the sender case to the - side of the battery.

By the way, the gauge goes to 80.  I'm checking for a pulse in a moment.
3 months ago
#2474 Quote
Ok, the voltage is Not pulsing. I've cracked fittings and am positive that I have pressure. So the sending unit must be bad, or not grounded.  Getting this thing off does not seem fun.  I'm assuming it's threads, NPT maybe??
3 months ago
#2475 Quote
Do not use teflon tape on the sender threads as it may insulate the ground connection provided by the sender threads to the motor block. You could tie a ground wire (about any gauge wire from 22 gauge to 12 gauge--use what you got!) to the battery ground and clamp the other bare end to the sender with a hose clamp. That will remove any doubt as to whether the sender is grounded without having to remove it from the engine. Does the gauge read zero with the engine running? Are you using the stock original sender?

Yes, the threads are NPT (National Pipe Thread--they are tapered and not straight like a bolt).

Let us know.
3 months ago
#2476 Quote
Yes, the gauge reads 0 while running. As far as I know the sender is stock style... it looks the same as what you buy on here. But as far as being the actual original, I don't know.  I've run out of time though. I have to go out of town tomorrow early and will be gone for a week.  A replacement sender is 35 bucks, so I may just order one that way it's here when I get back.  I'll keep y'all posted if it does the issue.  Thanks for those troubleshooting steps, that was a massive help on narrowing down the issue, and proving the gauge and wiring good.
3 months ago
#2477 Quote
If you have trouble removing the old sensor, try a crow foot wrench. They work good in tight spaces.
3 months ago
#2478 Quote
Okay, I couldn't resist. I ran out there and did one more check before I left. I am down the oil sending unit to the positive side of the battery AKA ground. And there was Zero resistance. That's telling me that the sending unit is in fact grounded to the block. The only thing left is what you have already suggested, a blockage in the sending unit or a bad sending unit.

I don't think I'll have time today to get this sorted, but it gives me something to do when I get back.