MJRemi Posted January 31, 2011 Share Posted January 31, 2011 My 89 had the dummy gauges. The 88 has full cluster. Everything seems to be fine except the oil gauge likes to stay pegged at 80+. It has moved a little while driving so it isn't stuck. My oil pump thing (or regulator?) next to the engine is covered in oil from when I bought the truck. Should the pressure concern me and how hard is it to swap out the regulator? Link to comment Share on other sites More sharing options...
Pete M Posted January 31, 2011 Share Posted January 31, 2011 did you swap out the oil pressure switch for the oil pressure sensor? Link to comment Share on other sites More sharing options...
comanche12 Posted January 31, 2011 Share Posted January 31, 2011 did you swap out the oil pressure switch for the oil pressure sensor? :agree: sound like he didn't swap the pressure from switch sensor to pressure sensor? Link to comment Share on other sites More sharing options...
1986Comanche Posted January 31, 2011 Share Posted January 31, 2011 did you swap out the oil pressure switch for the oil pressure sensor? :agree: sound like he didn't swap the pressure from switch sensor to pressure sensor? Where did he say that he swapped the cluster out? :dunno: Link to comment Share on other sites More sharing options...
comanche12 Posted January 31, 2011 Share Posted January 31, 2011 Where did he say that he swapped the cluster out? :dunno: My 89 had the dummy gauges. The 88 has full cluster. Everything seems to be fine except the oil gauge likes to stay pegged at 80+. It has moved a little while driving so it isn't stuck. My oil pump thing (or regulator?) next to the engine is covered in oil from when I bought the truck. Should the pressure concern me and how hard is it to swap out the regulator? :thumbsup: Link to comment Share on other sites More sharing options...
1986Comanche Posted January 31, 2011 Share Posted January 31, 2011 My 89 had the dummy gauges. The 88 has full cluster. Everything seems to be fine except the oil gauge likes to stay pegged at 80+. It has moved a little while driving so it isn't stuck. My oil pump thing (or regulator?) next to the engine is covered in oil from when I bought the truck. Should the pressure concern me and how hard is it to swap out the regulator? :thumbsup: He doesn't say anywhere that he put the gauges in the 88. :dunno: Link to comment Share on other sites More sharing options...
MJRemi Posted January 31, 2011 Author Share Posted January 31, 2011 Sorry for the confusion. I mentioned the 89 because I never had to evaluate oil pressure since the dummy gauge doesn't give readings. The 89 has the original full gauge cluster so now I see readings of the various pressures and such. I assume 80+ is too high but what do I fix to correct that? I'll take pics of what I believe is the sensor and you guys can tell me if I am correct. ( pics to follow ) Link to comment Share on other sites More sharing options...
dasbulliwagen Posted January 31, 2011 Share Posted January 31, 2011 Most service manuals list the correct pressures to be about 10 psi per 1000 rpm. But most good tight engines should see better than that when hot. Its just a minumum they use. Link to comment Share on other sites More sharing options...
Pete M Posted January 31, 2011 Share Posted January 31, 2011 try cleaning up the wire connection to the pressure sensor. Link to comment Share on other sites More sharing options...
MJRemi Posted January 31, 2011 Author Share Posted January 31, 2011 Is this it? Link to comment Share on other sites More sharing options...
Pete M Posted January 31, 2011 Share Posted January 31, 2011 yes and if you ever need to remove it, be very very careful. they like to snap off at the block. :( a couple days of regular soakings in PB Blaster is advised. Link to comment Share on other sites More sharing options...
Akula69 Posted January 31, 2011 Share Posted January 31, 2011 Most service manuals list the correct pressures to be about 10 psi per 1000 rpm. But most good tight engines should see better than that when hot. Its just a minumum they use. hmmm. My sons '89 was just re-worked and we put a high volume pump in it as well. At could start-up it shows 70-80 PSI but after warm-up it idles at around 20-25 PSI (at 900 RPM) We changed to a 5-30 oil and I told him to let it idle for about 5 minutes before pulling off - I was concerned the initial high pressure would blow out the rear main seal. Link to comment Share on other sites More sharing options...
Eagle Posted January 31, 2011 Share Posted January 31, 2011 Most service manuals list the correct pressures to be about 10 psi per 1000 rpm. But most good tight engines should see better than that when hot. Its just a minimum they use. Not the Jeep FSM. The spec is 13 psi minimum at idle, and 37 to 75 psi above 1600 RPM. In practice, most Jeep engines (other than those with real problems) typically idle at around 25 to 30 psi (warm engine) and run between 45 and 55 psi at highway speed. I've logged probably a million miles on just these engines, and I have never (that's NEVER) seen one that followed that "10 psi per 1000 RPM" rule. Link to comment Share on other sites More sharing options...
JeffN Posted January 31, 2011 Share Posted January 31, 2011 If all your other gauges read fine I would just replace the sending unit by the oil filter. Link to comment Share on other sites More sharing options...
MJRemi Posted January 31, 2011 Author Share Posted January 31, 2011 I gave the sensor plug connector a good cleaning but no change. With engine off the needle reads 80. While cranking over at start the needle drops to zero. Once engine is on, the needle goes straight to 80 and pretty much stays there. Do I need a new pressure sensor? I don't have any oil leaks to my knowledge and this motor was a shop rebuild 1 year before I bought the truck. Link to comment Share on other sites More sharing options...
MJRemi Posted January 31, 2011 Author Share Posted January 31, 2011 If all your other gauges read fine I would just replace the sending unit by the oil filter. Do I have to drain all the oil to swap it out? If so, I'll do it with an oil change in a couple weeks. Link to comment Share on other sites More sharing options...
JeffN Posted January 31, 2011 Share Posted January 31, 2011 no, it just unscrews and a new one screws in Link to comment Share on other sites More sharing options...
Eagle Posted February 1, 2011 Share Posted February 1, 2011 I gave the sensor plug connector a good cleaning but no change. With engine off the needle reads 80. While cranking over at start the needle drops to zero. Once engine is on, the needle goes straight to 80 and pretty much stays there. Do I need a new pressure sensor? I don't have any oil leaks to my knowledge and this motor was a shop rebuild 1 year before I bought the truck. Do you have a multimeter? The oil pressure sensor has an ohm range of 0 to 88 ohms. 0 ohms is for 0 oil pressure, and 88 ohms is 80 psi. Start your engine, let it warm up, then unplug the pigtail from the oil pressure sensor and connect the multimeter between the terminal on the sensor and the engine block. If it reads 88 ohms, the sensor is bad. If it reads significantly less than 88 ohms, the problem is the gauge rather than the sensor. Link to comment Share on other sites More sharing options...
MJRemi Posted February 3, 2011 Author Share Posted February 3, 2011 I replaced the oil pressure switch and the gauge needle now parks at 60 psi. I do not know what else to check so i will leave it alone for now. Thanks for all the help. Link to comment Share on other sites More sharing options...
comanche12 Posted February 3, 2011 Share Posted February 3, 2011 I replaced the oil pressure switch and the gauge needle now parks at 60 psi. I do not know what else to check so i will leave it alone for now. Thanks for all the help. 60 psi during at cold start? mine went close to that at cold start then dropping down as when engine warming up. Link to comment Share on other sites More sharing options...
Eagle Posted February 3, 2011 Share Posted February 3, 2011 I replaced the oil pressure switch and the gauge needle now parks at 60 psi. I do not know what else to check so i will leave it alone for now. Thanks for all the help. Do you have a multimeter? The oil pressure sensor has an ohm range of 0 to 88 ohms. 0 ohms is for 0 oil pressure, and 88 ohms is 80 psi. Start your engine, let it warm up, then unplug the pigtail from the oil pressure sensor and connect the multimeter between the terminal on the sensor and the engine block. If it reads 88 ohms, the sensor is bad. If it reads significantly less than 88 ohms, the problem is the gauge rather than the sensor. Link to comment Share on other sites More sharing options...
MJRemi Posted February 3, 2011 Author Share Posted February 3, 2011 I do not have a multimeter but it is on my long list of tools I want or need. The switch is about $5 and easy to swap out so I figured I'd just replace it. Good to have you back! You always seem have a lot of wisdom in your answers. Link to comment Share on other sites More sharing options...
Eagle Posted February 4, 2011 Share Posted February 4, 2011 Harbor Freight Tools sells a usable multimeter for a mere $3.99. At that price, I grabbed a couple. I keep one in the shop and one in my mobile toolbox. http://www.harborfreight.com/7-function ... 90899.html At that price, nobody has an excuse not to own a multimeter. Doesn't really matter if it's accurate to 1% over the full range -- 90 percent of automotive work doesn't need that level of accuracy. Most of what we do is "Yes, there's continuity" or "No there isn't." Link to comment Share on other sites More sharing options...
brdhntr Posted February 4, 2011 Share Posted February 4, 2011 Harbor Freight Tools sells a usable multimeter for a mere $3.99. At that price, I grabbed a couple. I keep one in the shop and one in my mobile toolbox. http://www.harborfreight.com/7-function ... 90899.html At that price, nobody has an excuse not to own a multimeter. Doesn't really matter if it's accurate to 1% over the full range -- 90 percent of automotive work doesn't need that level of accuracy. Most of what we do is "Yes, there's continuity" or "No there isn't." if you're on their mailing list, they have coupns for free ones right now. i have about 5 coupons so i'll be given away a couple to friends. they're not the best, but pretty close in acurracy to my craftsman. the price is right! Link to comment Share on other sites More sharing options...
JeffN Posted February 4, 2011 Share Posted February 4, 2011 On my 87 4.0 I just put a mechanical gauge in it, i put the gauge on the right side of the instrument cluster below where the factory clock goes. $20 and a holesaw was all i needed to get an accurate measure of the oil pressure. Link to comment Share on other sites More sharing options...
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