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  • Oil Pressure Problem

    I recently finished repairing the oil pan on my CJ, I had bashed it in pretty good and was losing about two quarts a week. Patched, brazed, done. Or so I thought. It seems my oil pressure has dropped since I put the pan back on. The damaged area was not near the screen in the back, however it was close to components of the pump. I have been told that the screen might be blocked up, I did try to flush the engine before I changed the oil.

    My pressure used to hold around 40psi. It dipped to 30psi as soon as I got it running again, and after driving it for 30 minutes it was down to 20psi.

    Any thoughts would be appreciated. I'm still waiting for a carb for my '65 F-100, so I'm having to use my moms TJ. I also have to make a cross country trip within a month, so the pressure is on (bad pun, sorry).

  • #2
    i have had this very same problem with oil pressure. Where as my engine got warmed up pressure dropped off. Eventually it got real bad and had pressure between 0 and 5. First check with mechanical gauge if you pressure is fine it is your guage in the jeep. If not guage check oil sending unit. $30 5 minute fix. If that does not help, Check oil pump. About a 100 - 150 fix 2 hours or less. (don't forget to prime the pump.) Finally the worst and most costly problem i have experienced and ultimately the cause for my prolem, main bearings. I had to pull my engine to fix these.

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    • #3
      i don't think it's your main bearings. you need to check it with a mechanical gauge. simply buy one at autozone, stick it on and read the pressure from under the hood. don't run it to the dash. if it still shows low pressure change the pump. you can change the bearings while you're there since it's an easy job. you don't have to pull the motor, you just have to pull the oil pan which it sounds like you're probably good at by now. i can change mains in about 2-3 hours. anyways, good luck and let us know how it goes.

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      • #4
        Main bearings???? Now you have me worried. How do the bearings affect the oil pressure? I'm not questioning you, just curious. The reason I worry about the main bearings is that there is a chance that some metal dust made it to the crankcase. The bearings aren't that old, but the possibility of premature failure exists. How long did it take for your pressure to start dropping?

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        • #5
          the main bearings have journals in them that the oil flows through. when they wear, the journal clearances get so small that the oil cannot flow through them and your pressure drops.

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          • #6
            How long do they take to wear? The only thing I'm worried about is the possibility of steel and brass dust in the oil. When I did the grinding on the pan, the jeep was 10 ft away.It worried me then, but I didn't have alot of options. I didn't notice any shavings on the crank, though they did cover the rest of the garage. I doubt that that would be the problem though, the jeep has been run for less than 30 min since the repair, and the system was flushed after the pan was back on. As always, Craig, thanks for the input. I have some towing questions I might run by you later.

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            • #7
              as far as wear that's impossible to say because it can vary so much. if you're worried about the dust then change the oil/filter and put in a magnetic drain plug. those can be had at auto zone/pep boys. but that's really about all you can do at this point. hind sight maybe you could have put a plastic garbage bag on the motor while you were working. but bad bearings will make the oil gradually keep dropping when the motor gets warm. if you're holding 10-15 on the gauge you're ok. some people let it go to 0-5 which is very very bad.

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              • #8
                Hey FUBAR, I thought the reason for oil pressure dropping on the mains is because the bearing is to worn and oil just flows past freely and it can't build pressure. Something similar to a leaky hose.
                But hey I have been wrong before, my dad didn't answer all my questions right

                I thought I better edit this...
                Copper he is right with everything he has been helping you with..

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                • #9
                  that's how a mechanic explained it to me. but i'm deaf and dyslexic so i wrong could be...oh, it's a little after 8:30

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                  • #10
                    I had a problem with my oil pressure to and it was so bad i called the guy that rebuilt it for me and he said nothin was wrong after he cut my oil filter in half and checked it!!!It was at 0 pressure and as soon as i put a new oil filter in it the pressure was fine again !!! it started to go down again and i changed the oil and bingo it was fine again !!Just my $.02

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                    • #11
                      cj7Geoti, how long do you go between oil changes? either WAY too long or you've got some serious sludge problems. might not be that the filter is the problem, might be that you're losing oil (consuming it) and when you get so low you lose pressure. then you change the filter and also fill it back up with oil.

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                      • #12
                        Originally posted by FUBAR
                        cj7Geoti, how long do you go between oil changes? either WAY too long or you've got some serious sludge problems. might not be that the filter is the problem, might be that you're losing oil (consuming it) and when you get so low you lose pressure. then you change the filter and also fill it back up with oil.


                        But I think if you had sludge you would have seen it in the oil filter.

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                        • #13
                          I have less than 2000 KM,s on a new engine and i have changed it 3 times!!! Never been down a drop !!! I figure its a just a spec a dirt or something on the gauge hose!!! This change seems to be the best pressure for the longest time yet !! Thanks

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                          • #14
                            Originally posted by cj7Geoti
                            I have less than 2000 KM,s on a new engine and i have changed it 3 times!!! Never been down a drop !!! I figure its a just a spec a dirt or something on the gauge hose!!! This change seems to be the best pressure for the longest time yet !! Thanks
                            Could be very possible. With a rebuild the hose could have gottin it when it was disconnected.

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                            • #15
                              ive got a similar problem. i know i should just post this in another topic but its the same kind of problem really. i recently did the inevetable. i hit my oil pump cover with the differential on my 74 CJ5 with the 304. dented the oil pressure release valve and well im sure you can figure the rest. if not follow the 6 miles of oil following me from my house to where she stopped when out of oil. now then, the engine is fine, but when i start it the oil pressure is up at about 70. after ive been drivin for a few minutes it goes down to about 35. any ideas?

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