xjkj92

So this past Thursday (1/28/16) when I was headed out on my lunch break I noticed my oil pressure gauge was fluctuating. I figured it was my sending unit so today (1/30/16) went ahead and replaced it. Well, it was still fluctuating. So I went up to Auto Zone and picked up a mechanical gauge and installed it......still fluctuating. It's going about like this, 50-15-20-40-10-0-15-20-10-20-0-05-0-15-40-0-20 and so on and its very rapid. That sequence would run through in about 15 seconds and this continues even once it's reached running temp. Also, there's no new noises, seems to be driving like she always has. I've put 50k on her since I bought it July 2014 and kept up with maintenance. I'm stumped.

RuffianXJ

I had a similar problem with mine but mine was solved with switching out the sending unit. When you attached the mechanical gauge did you attach it the the place where the sending unit goes? I have seen a ton of Debris collect in the area cause inconsistent readings. I high doubt the oil pressure is truly dropping and rising like that internally. You lifters would probably collapse here and there and you would get some clacking and awful sounds. Clean the port/passage. Change your oil I always run 5w30 thin oil is best for start up plus the oil stays put better while the engine is at rest. My 2 cents.

AKD.

xjkj92

Yes I hooked it up into the sending unit port. I'll definitely try cleaning it this morning though. I'll post back when I finish, thanks man!

cruiser54

Yup. A pipe cleaner, wire or zip tie can be used to clear the arterial passage.

bigbadon

A spun/spinning main bearing or cam insert can give those symptoms.

RuffianXJ

Pretty much worst case scenario, yes. I would suspect other issues though.

xjkj92

Didn't get a chance to clean it out yesterday, had to make an emergency trip and ended up driving her on about a 500 mile round trip. Didn't skip a beat though.

xjkj92

Maybe I shouldn't have just thought "screw it." She started knocking today, after almost 2k with no oil pressure. I swear sometimes this thing is magic.

RuffianXJ

I wish you more luck man.... Sounds like you ran out.
Drop ur pan.

xjkj92

It's all good man. I decided I'm just going to do a full rebuild on it since I'll be putting in a rebuilt trans and t-case anyway. In the mean time I picked up a 5.2 ZJ to daily and swapped the wheels/tires from the XJ over. It'll be my first time doing an engine rebuild by myself so now that I have another daily I can really take my time on it and learn as much as I can and do it right.