NotMatt Posted April 9, 2012 Share Posted April 9, 2012 So here's the history, 89 4.0L, AW4. Originally had dummy lights, swapped in a tach cluster with gauges and a brand new oil pressure sender (correct one for gauge, not a new dummy light one). After the swap, everything was hunky-dory. About 60 lbs cold pressure, and the gauge would drop to about 30 idling when hot and bump up to 50 or so while driving. Life was good. I had the front axle out for a 4wd swap and so I went ahead and pulled the pan and replaced the rear main seal since it was convenient. Silly me though, I didn't bother to remove and inspect the oil pump. Now everything is back together. At first things were the same as before as far as oil pressure goes. I drove it to work today and after getting about halfway there I noticed that the oil pressure gauge is pegged all the way to the right while idling. While driving or if I blip the throttle up a bit, it drops slightly and wanders around way above the 80lb mark, then pegs all the way to the right again once back to idle. I'm dreading the idea of finding that the pressure relief spring in the pump is sticking and I have to pull the pan again. Anyone ever had that problem and do the symptoms I described point to that being the issue? I supposed tonight I will see if I can dig out a mechanical gauge from the parts pile to put on there. That would at least tell me whether it's an actual oil pressure excess or just a electrical issue with the gauge or sender. Thoughts? Link to comment Share on other sites More sharing options...
Jeep Driver Posted April 9, 2012 Share Posted April 9, 2012 Clean your grounds.........sound electrical not mechanical. Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 9, 2012 Share Posted April 9, 2012 Yes, do verify that the gauge is reading the correct pressure first. Using a know good mechanical gauge is the best way. I had the same problem last week (reading high) and pulled the oil pressure sending unit. The no-pressure ohms reading was way out of specs from the output tip to the sender case ground. Installed a new sending unit and it's now reading normally. Hope your problem is a simple one too. Link to comment Share on other sites More sharing options...
jimoshel Posted April 9, 2012 Share Posted April 9, 2012 Remove the OP sending unit and stick a mechanical gauge in. See what your actual OP is, Could be a faulty sending unit or gauge, If in fact you do have a high reading then very likely it is the relief spring in the pump. Link to comment Share on other sites More sharing options...
NotMatt Posted April 9, 2012 Author Share Posted April 9, 2012 Yes, we'll see. Crossing my fingers that it's just an electrical issue with the gauge or sending unit or wiring in between. After googling around a little bit, I found this thread where the OP talks about the oil filter gasket blowing out and the engine stalling right after startup with the problem possibly being a stuck pressure relief valve.... mine is definitely running ok, but that doesn't mean it's not just "kind of" sticky and not fully stuck closed. I'll update this thread tonight when I test it out with a mech. gauge. Link to comment Share on other sites More sharing options...
Jeep Driver Posted April 9, 2012 Share Posted April 9, 2012 What filter are you using? I only use NAPA Gold or Pure1 myself now. After having two no-flow Frams............never again! Link to comment Share on other sites More sharing options...
NotMatt Posted April 9, 2012 Author Share Posted April 9, 2012 What filter are you using? I only use NAPA Gold or Pure1 myself now. After having two no-flow Frams............never again! Just put a brand new regular WIX filter on and filled it with 10w-30 Penzoil. Link to comment Share on other sites More sharing options...
NotMatt Posted April 10, 2012 Author Share Posted April 10, 2012 False alarm, just the gauge being wonky. I put a mechanical gauge on it and all is good. I put a new sender on it and cut the old connector off and crimped a new one on and it's still being funny, so I guess it's my gauge or cluster. Indeed it most likely is, because I forgot that about the time I did the rear main seal I put a new cluster in with a tach. So, when I have some time I'll probably dig out my old cluster that has gauges but no tach and swap the oil pressure gauge component into my tach cluster, if I can. Or I'll just put the mechanical gauge on permanent and skip the cluster gauge. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 10, 2012 Share Posted April 10, 2012 Might try this first: Improving the Instrument Panel Ground The ground point for the complete instrument cluster on your XJ or MJ is located up under the driver’s side dash. If you lay on your back and look up under there with a flashlight, without wearing a hat, you will see a black wire attached to a shiny piece of metal almost directly above the hood release knob. The screw will have either a ¼” or 5/16” head on it. This ground point is responsible for handling the ground circuit for the following items: Dome lamps, Seatbelt and key warning, trans comfort switch, wiper switch, headlamp switch and delay module, fog lamp switch, cargo lamp switch, all instrument panel grounds and illumination, power windows and door locks, cruise control dump valve, and a few more things. The problem is that where the ground point is located does not have a good contact with the chassis where the ground should be. The solution is simple. Make up a jumper wire with #10 gauge wire about 10” long. On one end, crimp on a ¼” round wire terminal. On the other end, crimp on a 3/8” round wire terminal. Remove the screw from the existing ground wire and attach the small terminal of your jumper so that the original wire and your new jumper share the same attaching point, one over the other. Look above the driver’s side plastic kick panel just forward of the top of the hood release knob. You will see an 8mm stud there. Attach the large terminal end there with a washer and nut over it tightened securely. **Special note for Comanche owners: Make your jumper wire 12” long and attach it on the driver’s side kick panel close to the fusebox on the 8mm stud.** Revised 11-29-2011 Link to comment Share on other sites More sharing options...
cruiser54 Posted April 10, 2012 Share Posted April 10, 2012 Might try this first: Improving the Instrument Panel Ground The ground point for the complete instrument cluster on your XJ or MJ is located up under the driver’s side dash. If you lay on your back and look up under there with a flashlight, without wearing a hat, you will see a black wire attached to a shiny piece of metal almost directly above the hood release knob. The screw will have either a ¼” or 5/16” head on it. This ground point is responsible for handling the ground circuit for the following items: Dome lamps, Seatbelt and key warning, trans comfort switch, wiper switch, headlamp switch and delay module, fog lamp switch, cargo lamp switch, all instrument panel grounds and illumination, power windows and door locks, cruise control dump valve, and a few more things. The problem is that where the ground point is located does not have a good contact with the chassis where the ground should be. The solution is simple. Make up a jumper wire with #10 gauge wire about 10” long. On one end, crimp on a ¼” round wire terminal. On the other end, crimp on a 3/8” round wire terminal. Remove the screw from the existing ground wire and attach the small terminal of your jumper so that the original wire and your new jumper share the same attaching point, one over the other. Look above the driver’s side plastic kick panel just forward of the top of the hood release knob. You will see an 8mm stud there. Attach the large terminal end there with a washer and nut over it tightened securely. **Special note for Comanche owners: Make your jumper wire 12” long and attach it on the driver’s side kick panel close to the fusebox on the 8mm stud.** Revised 11-29-2011 Link to comment Share on other sites More sharing options...
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