Hey guys, I have an odd problem. I noticed that my oil pressure was at about 10psi idle and about 35 at cruise. I decided to put in a new high volume oil pump. My oil pressure is now about 40 idle and 50 cruise. My problem is that my engine has a pretty bad engine knock. I filled the new pump with oil before putting it in and replaced the oil with 10w40 and new filter. The engine knocked at first then reduced, but never really went away. Now, I can hear it knock at idle after reaching operating temp. The engine still runs like a champ. If anyone has any ideas as to what this could be, please let me know!

which engine is it?

4.0L with 153000 on the clock

My experience with HV pumps is they suck.

Maybe it is pumping all of the oil to the top end, starving the bottom end of oil.

Maybe it is pumping all of the oil to the top end, starving the bottom end of oil.

X2......... add an additionl quart of oil to engine to see if this helps knock... HV pumps really shouldn't be used on non drag vehicles and/or vehicles without an enlarged oil pan for this very reason. You don't want to damage your motor trying to figure out what is going on, so be careful about this.

Hey guys, I have an odd problem. I noticed that my oil pressure was at about 10psi idle and about 35 at cruise. I decided to put in a new high volume oil pump. My oil pressure is now about 40 idle and 50 cruise. My problem is that my engine has a pretty bad engine knock. I filled the new pump with oil before putting it in and replaced the oil with 10w40 and new filter. The engine knocked at first then reduced, but never really went away. Now, I can hear it knock at idle after reaching operating temp. The engine still runs like a champ. If anyone has any ideas as to what this could be, please let me know!

To run a HV pump on a 4.0L you need massage the bottom oil pan to give extra clearance for the oil pick, did you do that so you have atleast 3/8" between the oil pick and the bottom of oil pan. My 4.0L has over 200K and I put a HV pump in to replace the 200K factory unit.

To run a HV pump on a 4.0L you need massage the bottom oil pan to give extra clearance for the oil pick, did you do that so you have atleast 3/8" between the oil pick and the bottom of oil pan. My 4.0L has over 200K and I put a HV pump in to replace the 200K factory unit.

If he didn't clearance the pan, what is happening is that the pickup is drawing in air through the crack he induced in the pickup tube.

This puts foamed oil into the bearings - which toasts the bearings of course.

HV pumps are fine, just make sure they clear first.

If he was sucking in air, the pressure gauge would be bouncing all over. It sounds like it stays at a solid 40. Where is the knock coming from?