I have a 1999 cherokee sport with 106k on it. About 2 weeks ago it started making a slight ticking sound around 1800-2500 rpms, almost like a small woodpecker on a piece of sheetmetal, its not lout like a rod or anything. The Oil gauge will start out normally with the first crank that day and will stay normal for about five miles then when i stop at a light or sign it will drop down to ten psi and after its fully warmed up in neutral or park the check gauges light will come on and it will be 0 psi.

I did some research and changed the sender and it reads the same. Because of the noise (which could be unrelated) I'm thinking maybe the oil pump!?

Anyone have any ideas or suggestions?

 

I have to ask...Have you checked the oil level? Low oil causes similar symptoms. I would definitely get a mechanical pressure gauge to verify pressure before replacing anything. Obviously avoid driving if you can.

 

Yes, I checked the oil the level is fine and the color is good.

 

The oil pump in those has been known to take a vacation. Remove the oil pan to change it.
While you have the pan off it wouldn't hurt to check a crank bearing or two with plastigage as well just to see how they're doing.

 

Should still verify your oil pressure with a "mechanical oil pressure gauge". Can be rented from many parts stores.

You may very well have low oil pressure but if it truly were zero, the engine would most likely be doing a whole lot of clanking.

You could have inaccuracy in the gauge itself in the dash.

Good data = Good decisions.

 

What brand of oil filter are you currently using?