Fluxuating oil preasure

[Adventure IQ]

My 94 yj with the 4.0 has fluxuating oil presure on acceleration and deceleration. Just changed oil in it, it is full. Normally it sits on the 3 (0-6 scale) and moves one to two notches as I rev or let off the gas. Has a tapping sound that has been there in the past...goes away once warmed up....but seems more prominent. Mechanic buddy has said the lifter tapping not an issue at this time. Whats up with the presure?

 

[Adventure IQ]

One thought is they may have used a lighter oil than I normally use when changed on Saturday....

 

[bob91yj]

Factory gauges in the YJ are notoriously inaccurate. How long have you owned the Jeep? Oil pressure readings will change with fresh oil vs old oil. You're on the right track with the viscosity question as well. YJ's were known for a piston slap type noise at cold start as well. I did lose a lifter on my '91 rock crawler.

If it is a lifter, you have two options, the first is kind of sketchy, use one of the engine flush additives before your next oil change. There's a chance that there is a piece of sludge or other crud causing the lifter to stick, flush MAY get it out. There's also a chance that stuff will break more sludge loose and make the situation worse. Option two is pulling the head and changing the lifters.

 

[Stumpalump]

15w50 syn or 15w40 dino for any flat tappet cam engine that is run below the Arctic Circle according to Mobil oils lab. Above the circle they said to thin the 15w50 with one quart 5w30 if it made me feel better. They said to cut the factory change interval in half not because the oil is worn out but because the anti wear chemicals that are limited by our government are all used up by then. Sorry if I turned this into an oil thread but thicker oil may help your pressure. Try some STP or Lucas oil stabilizer to thicken it up if you don't want to dump your fresh oil.

 

[jeep-N-montero]

One thought is they may have used a lighter oil than I normally use when changed on Saturday....

Don't you change your own oil? The weight of the oil can affect oil pressure, the filter will as well.

 

[Adventure IQ]

Good stuff..thx.

I like changing my own oil, but finding a dump spot, 60 plus hour week work load, coaching football, running a flying club, etc makes it diffiult. Oil is changed at 2-3k miles or before/after a major trip. Will try the stabalizer and then move to the heavier grade.

 

[Chris2000XJ]

You're oil pressure will fluctuate depending on RPM's that sounds pretty normal.

 

[Weeds]

You did not say how many miles are on the engine. Low and/or fluctuating oil pressure can be caused by worn cam or rod bearings. It may be time for a new engine depending on how hard you drive it. You may be able to connect an oil pressure gauge that reads the actual pressure.

Besides my 08 Rubicon I also own a 53 CJ-3A with the same problem.

Good Luck!!

 

[Kelly 4x4]

You may have a bad oil filter it happens more then you think use a good name brand filter & go to straight 30 weight oil for older eng,s .. Kelly