[rblahetka]

Hi. I would have searched for an answer but apparently either I am an idiot or I would need to upgrade my account.

At any rate, my neighbor has a Grand Cherokee with a 4.0. Not sure on the year but I am guessing around a 2000ish. At idle the oil pressure shows zero and the check guages light comes on. At cruising speed it will come up to about 40 PSI. I installed a new oil pressure switch and it is still doing the same thing. The Jeep has had this problem for about 2 months now so I am guessing it doesn't have low oil pressure although I haven't confirmed this with a mechanical gauge. I did read through the forums a bit and saw a few posts relating and most replaced the sending unit and all was better. My neighbor had gotten a new sending unit from Carquest or Napa, can't remember, but is this an item that should be an OEM piece only or will an aftermarket work fine? If it is a problem with the gauge, can I replace just the gauge or do I need top get them a new cluster?
Sorry for all the questions. I'm a tech for Audi, so not totally car stupid but it's been a long time since my independant shop days and dealings with anything domoestic. Any help would be great.

[greasefingers]

The search feature is temporarily not working.

When the jeep oil pressure sender is bad it does one of three things:
1- Pegs to the maximum (an electrical Open).
2- Stays on zero (an electrical short to ground).
3- Fluctuates all over the place (this is a cracked sensor diaphragm)

So it appears that your friends’ oil pressure reading is real (and on the low side). I have not seen this so I can only guess that it could be a clog in the oil passages or clogged pick-up tube on the oil pump. Since it is rather new I would not assume that the oil pump is worn. And then of course the last thing I would suspect is the actual gauge on the dashboard. They seem to read correctly and are usually sent a bad signal.

[rblahetka]

Originally Posted by greasefingers

The search feature is not temporarily working.

When the jeep oil pressure sender is bad it does one of three things:
1- Pegs to the maximum (an electrical Open).
2- Stays on zero (an electrical short to ground).
3- Fluctuates all over the place (this is a cracked sensor diaphragm)

So it appears that your friends’ oil pressure reading is real (and on the low side). I have not seen this so I can only guess that it could be a clog in the oil passages or clogged pick-up tube on the oil pump. Since it is rather new I would not assume that the oil pump is worn. And then of course the last thing I would suspect is the actual gauge on the dashboard. They seem to read correctly and are usually sent a bad signal.

Thanks for the quick reply. I think to be on the safe side I will do an oil pressure test just to be sure so they don't lose the engine. We have this BG engine oil flush stuff at work that works real well and I might give that a shot as well. With 2 kids at home they are on a fixed budget so I want to help them out in any way I can.

[greasefingers]

You’re a good man for helping them out!
The oil pressure sender unit has a 1/8 inch npt male thread on it. But mine is older than the one you are looking at, so it may be different. It would be nice if you had a street tee (2-ports female and 1-port male) that way you could look at the mechanical gage and compare it to the dashboard gage.

[SteelBlue_WJ]

Originally Posted by greasefingers

You’re a good man for helping them out!
The oil pressure sender unit has a 1/8 inch npt male thread on it. But mine is older than the one you are looking at, so it may be different. It would be nice if you had a street tee (2-ports female and 1-port male) that way you could look at the mechanical gage and compare it to the dashboard gage.

+1

good man

I know its not of any real help ,but kudos bro!