TheMayer

My 01 XJ's motor has been worrying me lately, knowing that I have the wonderful 0331 head and 116K on it. It has been consistently giving me low oil pressure readings at idle, (5-10 psi). It has always made a small "tick" from the valve train, but within the last few weeks the oil pressure has been reading very low after it warms up at idle. It has pressure with any amount of throttle but at idle it will drop. I am far from an expert on engine internals so I am hoping someone can give me some advice. I know it isnt the sender because I replaced it with an aftermarket electrical gauge.

I didn't have time to pull the valve cover today but I tried to get a decent video from the filler cap. I would really appreciate it if someone could tell me if what they see looks normal, or if anything jumps out at them. I started it for about 1 minute then shot the video.





Thanks everyone

Ant.

I am not sure but from what I can see, It looks like there is a white milky color in the valve cover, If that is white in there that iI am seeing, i would say you have water mixing with oil some how.. Wait for others to chime in and see what they say..

Ant...

TheMayer

I want to say that is from the flash on the camera, It doesn't appear to have any evidence of water, but then again I am not sure how obvious the white residue would be.

seniorgreenpants

All looks good in there. Just re-checked on "somedata" while at work.

Spec at Idle for oil pressure : 13psi

At 1600rpm and higher : 37-75psi

Pressure release is : 75psi

Water in the oil is most visible when first removing the oil cap and having a nice large white/light tan "foam" on the underside of the cap. Normally you wont see water in the oil when running.... unless its really really really bad. Damage is all ready done.

bigbadon

Glad to see another North Carolinian on here. I have the exact same symptoms on my 2000 4.0. I am very experienced on engines but new to the 4.0 so I have done tons of research on this problem.
A few fact on this issue:

1. most common to the 2000-2001 4.0 engines
2. factory had issues with cam bearings
3. head cracks
4. bad head gaskets

If your not losing coolant I would suspect #2.
Mine has 4psi, a little tick and runs like a scalded dog and has been that way for the past 40,000 miles! So don't panic.


What is your pressure at 1500 rpm?
What is your temperature?
What brand filter?
What type oil?
Does it tick warm? or cold?

F1Addict

Your head looks fine, I see no signs of coolant mixing. Your oil pressure is a little low at 9 psi. Most of them idle (warm) around 15-20. I'm not certain I would trust the accuracy of that gauge, though. If you're not having any other issues then stop worrying.

By the way, 99.9% of cracked 0331 heads were the result of overheating. If you've overheated in the past then you have cause for concern, if not... carry on.

TheMayer

Right now I'm running a Bosch distance plus filter with 5w-30 blend. Pressure at anything above idle is between 35-65, it likes to run at 200-220, and it ticks cold, but sometimes it will tick hot randomly.

The hottest it has ever gotten was 240 for about 2 minutes, then the aux fan kicked on and brought it right back down to 200.

djb383

Something could be wacked with those gauges. Have your oil pressure tested/verified with a mechanical oil pressure test gauge. Efan should be on by 218F coolant temp then off at 209F.

RubberSideUp

What weight oil are you using?

bigbadon

Your fine. Switch to 10-w-30 and don't look back.

salad

"Within the last few weeks" certainly indicates something is going on. Changes that fast are not a good sign. However it's hard to say WHAT changed.

Valve cover looks fine and engine sounds normal. Confirm that your gauge is accurate by screwing in a test gauge to that port. While it's out give the galley a good clean with a pipe cleaner or something, sediment and sludge will create a poor reading.

For a real look at the oil, drain it. If it looks muddy then there's contamination. If it separates after sitting for a while that's another obvious sign.

I'm not sure if a Bosch Distance Plus filter is a decent unit or not, try spinning a WIX (Carquest Blue, NAPA Gold) filter on there. Filters have a tremendous effect on oil pressure, bad ones are just bad, and sometimes there are the odd one-offs with defects that cause issues like this that can lead to damage if not addressed.

TheMayer

The issues started to get worse a few days after I changed the oil/filter now that I think about it. I didnt think about a different type of filter affecting pressure. I usually run the Mopar filter but it was out of stock this time so I picked up the Bosch. I may just drain the oil, let it sit to see if it separates, move up to 10w-30 since its getting warmer, and find a Mopar or Wix filter so I can rule out the oil/filter combo.

I am gonna check compression tonight or tomorrow morning to rule out head crack or blown gasket.

I appreciate all the advice!

salad

Sounds like a plan! No real reason to change to 10w30 by the way.

cruiser54

Excellent plan!! Just change the filter and see what happens. Post results. Check the oil pressure with a manual gauge after that.

djb383

U do know that 5W30 and 10W30 are the same viscosity at operating temp, right?......and u also know that when the oil is below operating temp 5W30 will flow quicker to the top of the motor than 10W30, right?