Hi guys,

I'm getting a crazy high reading from my oil pressure gauge. It's at 3pm basically.

The only thing I did today was change a motor mount and to pull the long bolt I had to move the oil filter unit to the left. I loosened the bolt under the unit and turned the unit to the lefty

My questions are:
How do I check my oil pressure manually?
Do you think I broke the sending unit and that's why I have a high reading?
Jeep is one owner and I've never changed the sending unit since I got it in 1991.

91 xj 4.0

Thanks,
Mike

 

I'd be willing to bet you have a broken sending unit, gauge pegged to the max is usually a dead give away of this. The releif valve in the oil pump is set at 75 psi so a reading higher than that generally indicates a bad sender.

To test the oil pressure manually you remove the electrical sender and screw the fitting for the mechanical gauge into the port.

 

since your going to unscrew it.. purchase a replacement so once you verify the pressure is fine.. screw in the new sensor..

 

You whacked the oil sender somehow.....

 

So from what I've read OEM only?

 

My aftermarket unit lasted one month. My MOPAR unit is still doing fine.

 

Yes OEM "Only".

When I change an oil sending unit I always check the oil pressure (hot idle) with a manual gauge. Then I know exactly where on the new in dash unit/sender shows that pressure.

Is it necessary no, I just like to know what it really is. When it comes to engines I'm rather ****.

 

Update: I ordered a new unit but last night i decided to give the unit a gentle tap with the hammer and lone behold it started working again! shut off the jeep and started it, didn't work... another light tap and bingo it works...


I'll still replace it but at least now i know what the problem is.

Thanks for all your help CF!

 

Pretty sophisticated diagnostics!!

I love it. Simple and you found the problem. Way to stick with it.

 

That is exactly how my oil sender works. Except I just have to wiggle it.

 

And if that doesn't work, get a bigger hammer!