beejakah

My 99 xj 4.0 has 252,xxx miles. Stock, daily driver. I always changed the oil on or before 3000 miles since I've had it the last 4yrs. I have no information on what had been done to it before I owned it. I've noticed a decline in performance over the last year or so, but nothing serious. (?) Tune-up type stuff usually solved the issue.

However, in the last few months I have experienced what many have with the oil pressure on the dash cluster dropping to 0 at idle. The pressure would go up when excelerate and increased rpm but it hasn't been where it should be (never got above 35ish even around 3200rpm). But there were never any real noises.. some ticking when the engine was cold but it would go away. Performance has also been at an all-time low.. it will serge sometimes when excelerate like it doesn't want to, then kick in, having issues starting and in the last couple weeks it has developed a wicked knock that is scaring the **** outta me.

When the oil pressure light and cluster gauge acted up with no real physical sounds or performance loss I thought it was the sensor. Bought a crappy one, pressure was worse, so I put the old one back in. I decided to fix my largest oil leaks (they were bad! Oil pan gasket and rms) and see what the oil pickup looked like. This was in January.



This is what it looked like as soon as I got the pan off. I only changed rms, pan gasket and cussed at getting the pan in and out. As would be expected, oil pressure cluster continued to be the same. *note: still no knock. Only some ticking and mostly when cold or idle. *note #2. No coolant or metal in oil.

February I fried my ignition coil and replaced that.

2-3 weeks ago I developed a knock/tap/tick at idle. Only at idle, and it was suttle but it didn't matter if the engine was cold or hot. Intermittent when at idle, or braking, very suttle when excelerating or not there when excelerating.

Last week I did my valve cover gasket (leaking bad), ventilation on cover and grommet and spark plugs (champion copper)/wires which improved idle and some performance and wanted to inspect my valves and springs.







They all appeared to be fine and tight. I expected to see sludge, a broken spring.. nothing. I replaced valve cover gasket and scratched my head.

The continued to develop into a KNOCK. Still intermittent as stated above, but worse. I checked the flexplate at the end of last week and the bolts were tight and no cracks to flexplate. I noticed a bolt backed out of the engine to bellhousing that may have caused the knock/rattle noise but after I tightened it this morning - no damn dice. As a matter of fact, it's gotten worse.
I've also developed a starting issue (all wires and grounds are clean, new starter last summer). I also tested the charging system off and under a load and it's fine. One or 2 times has been a no-crank, no start situation. Cps?

I bought a mechanical gauge for my oil pressure to see what's going on. I hope I didn't get a ****ty one that gave a faulty reading but I didn't have time to find another, wait or drive around looking for a better one



This first video is earlier when the engine is pretty much cold.
Jeep knock:
This second video is at operating temp. The sound is at the back lower part of the engine so the video starts under the driver side fender. I increased rpm to better test the gauge and pressure and all seemed to be ok? Given the gauge wasn't a POS and incorrect for the test?
Jeep knock 2:
I'm trying hard to keep this engine going. Sorry for the book, just know you guys on here know your stuff and wanted to give some history because I feel a couple things are going on.. maybe not but that's why I'm in need of help! Idk what the next step should be.
I was thinking the pump as of last week, but after the pressure test I think it's ok? The knock is freaking me out.
Any an all help is appreciated with this!
I'm trying not to drive it until something is diagnosed because now I'm thinking cam bearings, rods..etc. I don't know where to begin.

Jeep Driver

Sounds like collapsed lifters.

beejakah

Can you tell if that was a good way to test my oil pressure?

beejakah

I have to update this thread: I had missing bolts from my bellhousing to the engine. It was causing the knock/rattle and after I got the second one in and secure this morning the knock is no longer! Woo!

However, my oiling questions remain: was my test sufficient to determine my pressure? I know my sending unit and harness are shot (soaked with oil).

XJ-kee

I've heard of many people using this method to test their oil pressure, so I think that you're good to go. Seems like everything I read is to rip off that other sensor and throw in the mechanical one to diagnose a few different issues

For the bellhousing bolts, do you happen to have a pic on which ones were loose/missing?

I have a similar sound, although mine doesnt seem to rev up with the engine like yours did. I re-torqued the torque converter bolts and my sound went away probably 90%. But something faint is still there. Now I'm wondering if I'm missing a bolt or one is loose or something on the housing.

beejakah

They are the lower ones that connect the block directly to the bellhousing.

Mine must have backed out due to my oil leaks (rms, valve cover gasket and oil adapter) pissing on the back of the block and bellhousing. These have now been fixed. See my other recent thread on "missing bellhousing bolts?" Some guys gave me some imput on engine mounts, exhaust rattles, etc..

beejakah

I would really appreciate some more info on this oiling issue (no offense to previous posters). Because of my high mileage and such.. I keep going back and forth with replacing pump but I don't want a fresh pressure from a new pump to start blowing things out. I've been researching a lot on here and other forums (but you guys are the best ; D) to try and pinpoint some solutions. My oil pressure test has calmed my worries but Idk if there's some sensors that would help performance better - such as its a mechanical pump so if the engine is doing poorly, the pump will do poorly? O2 sensor & others that anyone can recommend to help with the aging motor? I have a bunch of other things I'd like do and need attention but it's not worth my time if the engine is about to STB..

bigbadon

given the age and mileage of your engine oil pressure is OK

beejakah

Thanks!