Oil pressure

[willtodo]

my oil pressure is fine (40)psi when engine is cool,, but after temp is up it drops down between 10-0 ,,, im using 10-30 castrol syn,,,,i guess the pump is going bad,,,can i get by with heavier oil.....how hard is it to swap oil pump

[Mudderoy]

my oil pressure is fine (40)psi when engine is cool,, but after temp is up it drops down between 10-0 ,,, im using 10-30 castrol syn,,,,i guess the pump is going bad,,,can i get by with heavier oil.....how hard is it to swap oil pump

With a lift I am able to get the oil pan off just by removing the oil pan bolts. The oil pump is right there, so I would say pretty easy. I've never replaced one so I'm not sure if you'd have to remove the distributor to install it. I suspect you would.

Get a Melling, standard flow oil pump, no high volume thing.

If you don't see an increase in hot idle oil pressure you may be looking at worn bearings, rods, mains, etc...

Oh, maybe you don't have to remove the distributor...

2120]

[nickyg]

My oil pressure was reading low. 20 when cold ,0 when it was hot. then one day when changing my oil. I broke the sending unit (by the oil filter) I had a used one I cleaned up and cleaned the hole it threaded into and now my pressure reads 40 cold 20 hot.

[Mudderoy]

My oil pressure was reading low. 20 when cold ,0 when it was hot. then one day when changing my oil. I broke the sending unit (by the oil filter) I had a used one I cleaned up and cleaned the hole it threaded into and now my pressure reads 40 cold 20 hot.

Damn I forgot all about this. Yep same issue with our 1999. Started reading ZERO but no tappet noises. I changed out the oil sending unit and back to normal pressure readings. 5 to 10 psi is normal with a hot engine at idle.

[denverd1]

yep. check the sending unit first. Prone to breaking for sure. And the dizzy does not have to come out to replace the pump.

tony, just curious why not to go with high flow pump? Sounded good at the time so thats what I did..

[msmoorenburg]

yep. check the sending unit first. Prone to breaking for sure. And the dizzy does not have to come out to replace the pump.

tony, just curious why not to go with high flow pump? Sounded good at the time so thats what I did..

I've seen way to may high volume pumps suck the pan dry, and starve the engine for oil

[denverd1]

hmmm... kinda make ya wonder where 6 qts of oil went but I'll take your word for it!

[OrangeXJ]

Damn I forgot all about this. Yep same issue with our 1999. Started reading ZERO but no tappet noises. I changed out the oil sending unit and back to normal pressure readings. 5 to 10 psi is normal with a hot engine at idle.

what tony said change the sending unit on top of the oil filter 5-10 hot is ok at idle

[willtodo]

thanks guys,,,,

[willtodo]

Update......I changed my oil and discovered that there was a fare amount of sludge in the oil pan,,,something that I had not noticed before ( ive hade the jeep one year) I think this would be the second oil change since ive had it...when I changed the filter it had quite a bit accumulate in it....there was a slight milky look on the fill cap, but no odd color to the oil itself ...I switched to synthetic ,,could that have caused a reaction with the regular oil,, or do I have a leaking head gasket and the water caused it... the oil change has corrected the low pressure issue and I haven't seen any signs of water,,it has about 500miles on new oil,,,,??????????

[denverd1]

got some water in there somehow. IIRC, 2000 is the suspect head year.... does it run hot? use water?

[Mountain Goat]

Update......I changed my oil and discovered that there was a fare amount of sludge in the oil pan,,,something that I had not noticed before ( ive hade the jeep one year) I think this would be the second oil change since ive had it...when I changed the filter it had quite a bit accumulate in it....there was a slight milky look on the fill cap, but no odd color to the oil itself ...I switched to synthetic ,,could that have caused a reaction with the regular oil,, or do I have a leaking head gasket and the water caused it... the oil change has corrected the low pressure issue and I haven't seen any signs of water,,it has about 500miles on new oil,,,,??????????
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What year is it?



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[willtodo]

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What year is it?



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Its a 2000,,,,, it boils over sometimes when I kill it,, but as long as I keep it topped off it doesn't run hot...

[XJ Wheeler]

It shouldn't be boiling over if its not overheating.

[Cheromaniac]

Update......I changed my oil and discovered that there was a fare amount of sludge in the oil pan,,,something that I had not noticed before ( ive hade the jeep one year) I think this would be the second oil change since ive had it...when I changed the filter it had quite a bit accumulate in it....there was a slight milky look on the fill cap, but no odd color to the oil itself ...I switched to synthetic ,,could that have caused a reaction with the regular oil,, or do I have a leaking head gasket and the water caused it... the oil change has corrected the low pressure issue and I haven't seen any signs of water,,it has about 500miles on new oil,,,,??????????

I hope I'm wrong but you could be one of the unlucky owners of a 2000-2001 4.0L Jeep model whose cylinder head has cracked. Those early #0331 castings are notorious for cracking in the middle between the no.3 and no.4 exhaust valve springs (the hottest part of the head) because the castings were too thin. A mystery loss of coolant and milky residue inside the oil filler cap are the early signs of a problem. As the oil becomes contaminated with coolant, the bearings will suffer accelerated wear and the oil pressure will steadily drop.
Pull the valve cover and if you find a streak of milky residue +/- coolant droplets in the abovementioned location, you'll need to replace the head.
Fortunately Jeep rectified the problem from '02 onwards with reinforced castings (you can also find reinforced castings from Clearwater Cylinder Heads and Alabama Cylinder Heads) so you can cure the problem once and for all.

[willtodo]

Im afraid your right,,,,,a fresh head on that block wont hurt anyhow,,,engine has 107,000 ,,