msd131

is the oil pump on the 4.0 i6 really bad for going bad? took mine out and it seems fine from looking at it......its just metal gears, dont see how that can go bad............is there a way to test it? a new one is like $80.00 and thats steep on me right now. rod bearings look sweet though, no prob there. maybe cam bearings? dont know but im hoping its the pump. my pressure loss is bad and I dont know what to do at this point.

freegdr

a oil pump is one of those parts if youve got it out put a new one in...........

msd131

if I had the funds to buy a new one i wouldnt be on here asking if it can be tested.

freegdr

lets pu it this way is it from the 92 cherokee and you test it ,it test good you put it back in and in a month or two it gos bad now your taking it bak out to put on in any way if its not out usung a manual oil pressure gauge where the oil sending unit is is the way to test them other than that how will you no what pressure its building.

freegdr

http://www.aa1car.com/library/2005/us020516.htm

2Evil4U

The main mechanical failures for a positive displacement pump like your oil pump are either shaft breakage (the shaft that usually runs down from the distributor to turn the thing) or wear.

If the shaft is OK and it turns freely and the gears don't have much backlash it is probably fine.

That being said, unless you checked the oil pressure with a mechanical gauge prior to pulling the pan and the pump you're shooting in the dark.

msd131

I put it on yesterday after flushing the engine out really well.the oil pump is clean and nice looking. the gears are tight like they are suposed to be and the pickup tube and screen are clean. if the rod bearings are good looking as they are, should'nt the cam bearings be the same.....or could the cam bearings be scored and not the rod bearings. i'de think if the cam was scored then the rod B would be also but im far from mechanic status........

msd131

that answered alot for me.......still hope the pump is the problem.
is there anyway the cam and bearings can be checked that you may know of since the pan is off at this point. im just gonna break myself and go buy a pump tomorrow and see if it fixes it for me. man I wish i could hit the lottery. being broke really sucks! but I think of all the people in japan and I cant complain. may God bless them........my heart goes out to the japs.

2Evil4U

Whether you install a new one or keep the old, make sure to pack the gear cavity with vaseline or bearing grease or it may not prime properly.

fishtaconc

X2, dont want to start it and no oil moving through the engine.

TbDk

Dont know if I missed it or not, but what was your oil pressure at? What is making you think the oil pump is bad?

msd131

till the engine warmed then it dropped........40 at start then 15 then 10 then 5 then 0 all in just a few min.