Slick761

So I was doin some muddy hill climbs today having a grand old time and I TACHED IT OUT! I didn't see how high it went but it was probably at least 5500 maybe 6000. The engine sounded fine and surprisingly smooth but after that I noticed my oil pressure gauge.... My oil pressure gauge started reading about 5psi at idle. On the way home it read about 25 at 1800. Usually its around 40. I'm hoping its the sending unit because I've always had an issue with it jumping around on and off. The engine isn't smoking or anything and the oil is still full. When I got home I let it sit for about 5 minutes and started it again and the pressure at idle was back to 20. Anyone have any input on this?

trust96xj

I it's back to normal I wouldn't worry about it too much. Mine jumps around alot. Esp after I change my oil.

freegdr

get new switchs

Slick761

Ya I put a crappy stp filter on it recently so I figure ill go all out and get the adapter for the extra capacity oil filter and change the pressure sending unit. I thought maybe the oil got realllllllly hot but it shouldn't have cause the engine was running 200-205 the whole time. At some points the gauge read almost 0. The engine wasn't making any unusual noises though. It sounded quiet and clean. No rod noise not even lifters tap.... Even when I accidentally revved to 6k it sounded clean and smooth. Im hoping the sender is just starting to crap out.

DFlintstone

Ya, know, mine has levers and stuff down there, kind of between the seats. Some times when I move them around, the engine doesn't seem to need to go so fast.
Hope it's your sender.

I know nothing about the pressure relief valve...don't you have sewing machine oil in there?

cruiser54

Do this when you change the sender. Or maybe the high revs blew out some of the crud in the passage that this thread addresses.
http://www.jeepforum.com/forum/f19/4...fixed-1304679/

Wix or Napa Gold oil filter in standard capacity is fine. Frequent oil changes with quality filters are more important than high capacity oil filters.

Slick761

Hah thank you very much..... The guy that wrote that up had the exact same symptoms I do. I betcha that'd why it jumps up or down sometimes too. That little 6k burst moved somethin around. I will try that ASAP. Ot sounds like its gotta be it..... If the thing really was like 2 psi for any period of time I would have gotten some.... Well noise.

cruiser54

My thoughts exactly on the "burst".

DFlintstone

Hey bud....no news is good news?

cruiser54

Running the pi$$ out of the 4.0 periodically is good for it.

BTW Flintstone, I wired a switch into my MJ yesterday so I can prevent TC lockup or take it out of lockup on hills.

Slick761

Haven't gotten a chance yet. Hah ill tell ya somethin though, that 4.0 sure revs quick since I fixed everything up... It was tagging 5k easy with a blip of the throttle. It used to struggle a bit to get up there.

DFlintstone

Pete, you get a little "thank you", every day I drive down my hill, staying in 2nd without having to use the brakes OR worrying about having it kick down into first. It takes about 10 minutes to get down, that's plenty of smilen' Where did you put your switch?


Does it sound like "Christean?".
Didn't you mention you ported it some? (one mod I would consider). Sounds pretty slick....you might check this out http://www.jeep4.0performance.4mg.com/tech_specs.html I believe that's a stock cam graph at the bottom showing max torque at around 34, and max horsepower at around 44. Some days I keep her under 1,800 myself. (28lbs IS the correct throttle return spring pressure?)

I wanted to re-post this CPS test for a 97 that 89Laredo found. In the first Vid he's back-probing the red wire looking for 1/2 a volt, if I see that right. http://www.cherokeetech.com/VBull/sh...agnosis-Videos

cruiser54

Close to me in the vertical part of the center console.

5-90

1) RENIX doesn't have a rev limiter - I bounce mine off of the 6,000rpm line about once a quarter or so.

2) Do not stay around the range of 6,000-7,000rpm for very long - you can get crankshaft harmonics which can actually lead to snapping the crank! Under that is just fine, and Barney Navarro balanced his Indy engines to run around 9,000-10,000rpm (Barney Navarro, I believe, was the one who discovered the crank harmonic issues - he rand a turbocharged, destroked AMC 6-199 at Indy, and did rather well!)

cherokeelaredo'90

I don't mean to thread jack, but could you maybe do a write up on how you did this? It seems pretty interesting. Thanks!
And to the op I have a renix aswell, but if an engine doesn't have a rev limiter, will it just rev till it, well, blows up?