I changed the oil sending unit awhile ago because I thought it was bad showing sporadic numbers and moving a lot with acceleration/deceleration. It got a little better and less variation. Like I said this was awhile ago and I really didn't think much of it, and more or less ignored it after that since they are known to go bad.
I started hearing a noise a short time ago when at a stop light. I played around with it and it is worse when in park or neutral, goes away when loaded. Based on what I read on here I pulled the pan to look for piston skirt pieces or any "sparklies". There were no metal pieces or particles that I could find. Everything looked/felt ok to me.
Since I was dropping the pan I also decided to do the the Oil Pan gasket, RMS, Oil filter adapter O-ring, and distributor gasket. I ended up finding that my valve cover was really loose and replaced that gasket as well.
Everything has been back together for about a week now. I think my leaks are gone, which is a nice bonus. I also noticed my oil pressure on the gage is much more stable. I'm pretty much at 40 or a little above most of the time, other than when at a stop light. When at a stop light it drops to around 20, sometimes less but not much less.
I'm wishing I had changed the oil pump while I was in there because now I'm thinking that may be the culprit. I ordered a new oil pump and plan to replace it.
All the symptoms point to low pressure and a noise to go along with it at idle other than the gage reading. I'm going to see if one of my local autoparts stores has the mechanical pressure gage to double check the sending unit reading.
TL;DR When engine warmed up, loud noise at low pressure during idle while in park or at red light, but oil sending unit still shows good pressure. Planning oil pump change and mechanical pressure gage test
Can the oil sending units show false good pressure? Meaning my pressure is actually low, but shows good.
It's not a knock and its not a tick. I initially thought it was a driveshaft noise or a bad u joint hitting something but the noise is definitely coming from the pan area.
Thoughts? Any reason not to change the pump? Seems like a cheap/easy shot in the dark.
1995 White XJ 2-Door Sport 145K miles
4.0 6L, 4.5" RC full leaf pack, coils, and fixed length LCAs, IRO Rear BPEs, Front YJ Brakelines, IRO HnT SYE with Front DS, Cragar Blk D-Window 15x8 4"bs, General Grabber AT2s 33x12.50, Rear Hitch with Warn D-Ring Shackle, Dynomax Super Turbo, HD Offroad Shackle Relocation brackets, IRO Front Hooks, Fenders Trimmed, Stock Flares relocated, floor pans replaced.