Once the engine in my 90xj 4.0l has gotten up to temp my oil pressure ussually is sitting at about 17 on the regular gauge and maybe 5-10 on the mechanical gauge I have. Also once it has gotten to temp it has a noticable knock at idle but deffinately goes away when I accelerate or pretty much over 1000rpms. The location of the sound has proved to be extremely hard to locate no matter where we listen it seems we can't identify the location of the knock(using a long ratchet extension with our ear to it to listen for it). We think it is in the very top of the engine but still not completely sure.
As far as history on the engine previously this year the L arm that holds the oil filter up had to be replaced when the seals in it broke(??), The rearmain seal was also done at that time. Then after that I had extremely high oil pressures(70-off the gauge). So I had to replace the blow by system because it was so clogged and had never been cleaned. My jeep had also been running at about 210+degrees at that time but everyone here said that was normal. Well a couple of weeks ago I flush my radiator system and checked my thermastat using the boiling water technique, it never openned even when the water it was in was boiling. So I replaced the thermastat and am now running 180*. The low oilpressure and knocking had appeared around the time after redoing the blowbye system. I was actually getting 0 psi at idle when the jeep had been driven a lot, on both gauges until I switch from 10w30 to 20w50.
As far as history on the engine previously this year the L arm that holds the oil filter up had to be replaced when the seals in it broke(??), The rearmain seal was also done at that time. Then after that I had extremely high oil pressures(70-off the gauge). So I had to replace the blow by system because it was so clogged and had never been cleaned. My jeep had also been running at about 210+degrees at that time but everyone here said that was normal. Well a couple of weeks ago I flush my radiator system and checked my thermastat using the boiling water technique, it never openned even when the water it was in was boiling. So I replaced the thermastat and am now running 180*. The low oilpressure and knocking had appeared around the time after redoing the blowbye system. I was actually getting 0 psi at idle when the jeep had been driven a lot, on both gauges until I switch from 10w30 to 20w50.