High oil pressure is typically due to high resistance somewhere in the system. Have you been changing your oil and filter on a regular basis? If you haven’t changed the oil filter in a while, that would be a good and cheap start (not assuming you are bad at routine maintenance, just trying to go through possibilities). Also, If there is a build up of sludge you could see higher oil pressures as ducts, channels and baffles can become clogged. Perhaps a piece of trash is stuck in the system? Does the engine smoke and if so, perhaps the PCV valve is clogged causing high crank case pressure and leading to bad oil flow? There could be several reasons and since the external unit corroborates with the factory gauge, it’s time to look elsewhere in the engine to find the culprit. Now that you have the new oil pump (heart transplant) and the new sending unit (EKG monitor) it’s time to find the clog (blocked artery). Going to have to do some digging.
High oil pressure.
I have a 96 Cherokee. I replaced the oil pump and my oil pressure sits at 70. I have replaced the sending unit a couple times and bought an external gauge which all confirm the oil pressure at 70.
Any thoughts on what could be causing this?
Any thoughts on what could be causing this?
1 - 14 of 14 Posts
High oil pressure is typically due to high resistance somewhere in the system. Have you been changing your oil and filter on a regular basis? If you haven’t changed the oil filter in a while, that would be a good and cheap start (not assuming you are bad at routine maintenance, just trying to go through possibilities). Also, If there is a build up of sludge you could see higher oil pressures as ducts, channels and baffles can become clogged. Perhaps a piece of trash is stuck in the system? Does the engine smoke and if so, perhaps the PCV valve is clogged causing high crank case pressure and leading to bad oil flow? There could be several reasons and since the external unit corroborates with the factory gauge, it’s time to look elsewhere in the engine to find the culprit. Now that you have the new oil pump (heart transplant) and the new sending unit (EKG monitor) it’s time to find the clog (blocked artery). Going to have to do some digging.
Thank you for chiming in on this. There is a new oil filter and oil. I replace the rear main seal along with the gasket for the oil pan and valve cover. Any idea where I should start looking for potential blockages.
I suspect you ended up with a high volume pump. Not a bad thing. However there is a spring and poppet ball in the pump that acts as a relief valve. If you take that out and put the old spring in you will probably decrease pressure. I wouldn't worry too much though, I used to stretch that spring out so I could have more pressure for pulling the engine down and working hard at idle
I just looked at the box that the oil pump came in and I did end up with a high volume pump. Am I safe leave it on and run with it?I suspect you ended up with a high volume pump. Not a bad thing. However there is a spring and poppet ball in the pump that acts as a relief valve. If you take that out and put the old spring in you will probably decrease pressure. I wouldn't worry too much though, I used to stretch that spring out so I could have more pressure for pulling the engine down and working hard at idle
Yup, that is one of the things I do when rebuilding engines. Most people that have the 4.0 complain about low oil pressure, so if it was mine I would have added a high volume pump a long time ago. This is good insurance if you are pulling your engine down when crawling etc.
Thanks for the info. Should I reduce the viscosity down to 5W-30 from 10W-30? Is the oil pressure running at70 to 75 two hi long-term?Yup, that is one of the things I do when rebuilding engines. Most people that have the 4.0 complain about low oil pressure, so if it was mine I would have added a high volume pump a long time ago. This is good insurance if you are pulling your engine down when crawling etc.
Personally I don't like thin as water oil in an engine. I think it causes premature wear on the crank bearings. Manufacturers use it to boost milage. However the 4.0 in vehicles that recommend that low viscosity oil develop engine knocks at 150K
It’s good to hear it’s just a high volume pump! I apologize for assuming it was a standard replacement pump. 4.3L XJ hit the nail on the head since you ended up with the high volume pump. I feel a sense of relief for you, Jake!
Good afternoon! I replaced the oil pump with a standard flow and my pressure came down a little but is still sitting at 55-60 with an external gauge connected to the sending unit port. Any thoughts on this?It’s good to hear it’s just a high volume pump! I apologize for assuming it was a standard replacement pump. 4.3L XJ hit the nail on the head since you ended up with the high volume pump. I feel a sense of relief for you, Jake!
It is a good thing, don't knock it. It means you have low engine wear
Yeah, it seems like that’s where it wants to live if you don’t have any sludged up spots in the engine. My oil pressure drops at idle and then bounces up to 50-55 under throttle. I’m not worried about it. I don’t wheel or have 4WD but if I did, the high flow pump is the way I would want to go.
Probably a high volume oil pump. Higher oil pressure is much better anyway. It's not going to hurt anything. My XJ runs 70-75 cold and 60psi warmed up.I have a 96 Cherokee. I replaced the oil pump and my oil pressure sits at 70. I have replaced the sending unit a couple times and bought an external gauge which all confirm the oil pressure at 70.
Any thoughts on what could be causing this?
1 - 14 of 14 Posts
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