Low oil pressure. Is it the timing chain?

jeep
grand-cherokee

#1

I have low oil pressure. Ive changed the oil …the sending unit… both the cam bearings and rod bearings. No over heating no smoke. Ive even used aditives for both the engine and radiator. Still i have low oil pressure. Could it have anything to do with the timing chain?


#2

Are you asking if the timing chain would cause low oil pressure? Maybe it’s the other way around? I would think that being low on oil would cause your timing chain to suffer an early death;

Is the pump driven by the crankshaft?


#3

Year? Engine? Miles?


#4

If the main bearings are worn, the car will still have low oil pressure. Same if the oil pump is worn out. The timing chain, no, not the cause of low oil pressure.


#5

What do you consider low oil pressure?

What is your oil pressure at idle? at highway speeds?

Other causes of low pressure could be the oil pressure relief valve, oil pump, bad oil filter.


#6

+1
I think that the OP may be confusing cause and effect.
:thinking:


#7

While you were in there you really should have considered the main bearings and no, the timing chain has nothing to do with low oil pressure although lax oil changes, running the oil level low, and so on can wear he chain out.


#8

You’ve had the oil pressure tested using a shop’s pressure gauge too, right? If not, suggest you do that test, to rule out your car’s sending unit as the problem. This engine hasn’t recently been rebuilt, right? If it has, the rebuilder may have made a mistake, like forgetting to install the required stops for the oil passages (galleries). If the pressure is actually low, the most likely cause is worn crankshaft bearings. The oil delivery system is sort of like a long garden hose that has dozens of small holes in it along it’s length. As long as those holes aren’t too large, the oil pump can still maintain proper pressure in the hose. But if the holes get too big, too much oil leaks out, and the pump can no longer maintain enough pressure. The “holes” in this analogy are the bearing clearances, w/the biggest “holes” occurring in the crankshaft bearings. I’ve never had to deal w/that problem myself, so don’t know what kinds of tests can be done to verify that’s the problem. I think crankshaft bearing clearances – a measure of the size of the “holes” – can be measured by removing the oil pan on some engines, maybe that is how it is done. Typical crankshaft bearing clearance is on the order of 1-2 mil as I recall. If yours tests out as 4 mils, then you know that’s the problem. Very unlikely to be the oil pump, since it runs bathed in oil all the time. Before going to the trouble of measuring the bearing clearances, good idea to test the wet vs dry compression. Best of luck.


#9

No. Its in the front of the crank shaft.


#10

Yeah i changed everything. Still getting low oil pressure


#11

My oil pressure at idle drops to 5. When im driving it goes back to 40 but then drops back to 5 when i stop


#12

2000 jeep grand Cherokee… 166.005 miles … straight 6 4.0


#13

Yes. Confirming actual oil pressure is step one.


#14

Sounds like a somewhat worn engine. But if 40 psi is in spec, I wouldn’t worry about it. Those 4.0 engines are pretty tough, they can handle low oil pressure at idle. But it’ll slowly get worse.


#15

Oil Pressure Specs, straight 6 4.0L

Idle: 13 psi or greater
1600 rpm and higher: 37-75 psi

So yes, it looks like the higher rpm pressure is good , but the idle oil pressure is a little low. Double check both of those using a calibrated shop gauge, and be sure you are running the correct oil spec, 10W-30 above 0 deg F.


#16

5psi is really low, in my opinion

I would start saving for another vehicle

I think the engine is worn out . . . don’t waste time replacing the oil pump


#17

Lol… to late… you know i think i was frustrated ar the time so when i was replacing the bearing i never thought about the rear main seal (although I looked at it a few times) so im in the process of replacing that and the oil pan gasket as a last result.


#18

I changed the main bearings but i was alittle silly and didn’t think about the rear main seal… although i looked passed it a few time. Im in the process of replacing that now as a last option.


#19

Sorry for the last response i though i sent it… 2000 jeep grand Cherokee 166.000


#20

I changed out the pump rod bearings and crank main bearings. But i didn’t change the rear main seal or oil pan gasket which im in the process of replacing now