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  • Oil Pressure...part 125

    I've been reading the oil pressure wars on about 124 threads this morning looking for the answer to my problem. Fubar came the closest to having my problem, but there was no answer.

    1978 CJ7 304 20 hours since rebuild. Went with a slight upgraded performance cam and HEI. Oil pressure read a perfect 75 psi (as this is when the pressure spring opens) Oil warms up and pressure stayed around 50-60. Minimum for the engine is supposed to be 35 for operating RPM. 13 I think for idle. Two days later I was driving down the road and it starts to back fire. I adjust the Edelbrok 4 barrel to richen the mixture...I'm good to go again. 2 hours later, a funny knock comes from the engine. It sounds like a push rod tapping the valve cover. I pulled the right cover (as seen from the inside the Jeep), and see a push rod has punched through a rocker cup. I replace the rocker and push rod, and pick up a piece of the old rocker off a valve spring. Drive home, no problems. Drive to the store next day to get oil for oil problem. Leave the store, no oil pressure at all. This isn't a guage issue, because I can hear all the chattering in the engine.

    I have put new impellers in the pump, new pressure spring and plunger, cleaned the oil pick up screen and tube, blown out the port from the p/u tube to the pump, changed the bottom plate of the pump, changed the oil three times, and used a few choice words. The most pressure I get is 5psi. This isn't enough to stop the chattering. Any other ideas? How do I check to see if the pump is actually spinning? This is my last thought. I did see some scoring on the pump impelers that wasn't there when I built it. Could I have injested a piece of the rocker into my pump and sheared something above the pump? How do I check it without dismanteling the whole front of the engine?

    Anyone have a free 360 they want to give me?

  • #2
    Score one for my wife. She says we know the pump is spinning because the petrolium jelly I had to pack the pump with is gone after starting the engine. Am I just not getting a good prime? Is this a difficult thing? I'm really out of ideas.


    • #3
      Again I really am unfamilliar with AMC V8's but Can you spin the oil pump with a screwdriver on a drill like people do to pre-oil an engine before starting. At least you can see if any oil is pumping.

      Maybe pull the sending unit out and see if any oil get's pumped out. Maybe put a hose on it to keep it from getting messy.


      • #4
        yes, you can prime the pump though the dizzy hole. i haven't torn mine apart to find the problem but i'm willing to bet it's either a main bearing issue or a galley plug that came out. a worn timing cover can also cause the gears to fail and in my case, the dizzy gears to wear very quickly.


        • #5
          did you change the timing cover, if you changed the pump gears i would also change the cover like fubar said. i did and i put the new gears in the old cover just to see the clerance compared to the new cover and you could see daylight. new gears new timing cover no daylight, tighter than a dophins a$$.
          good luck, keep us posted as to what you find. 1tuff


          • #6
            Originally posted by FUBAR
            willing to bet it's either a main bearing issue or a galley plug that came out. a worn timing cover can also cause the gears to fail and in my case, the dizzy gears to wear very quickly.
            Galley plug? That's a new one for me. Are you calling your gear impellers "dizzy gears"?

            I thought that I shouldn't spin the pump by hand, since the pump isn't in the tank. Could you give rudimentary instructions on how to do this? I am thinking I haven't packed enough jelly to get it primed. If this isn't the answer, I'm out of ideas.

            I guess I may have to pull the timing cover off. I didn't want to, but I guess I'll take a long weekend and do it.
            Last edited by 47driver; 09-27-2006, 04:20 PM.


            • #7
              47driver sorry for your woe's. i also just spent alot of money rebuilding my 401 1,700.00$. i see you spent 1,300.00.$, plus a new timing cover= roughly 1,700.00$. i hav'nt started mine yet though, hopeing it works out. i'll follow this to see if i might also have to do something else. i'm not sure but i think fubar is talking about those gears that are driven by the distributor. i know mine were worn out thats why i optide to get a new cover and oil pump cover and gears, to try and cover all my base's. hope that helps.
              Last edited by 1tuffcj; 09-27-2006, 06:52 PM.


              • #8
                All engines have an oil pump pickup of some sort, and most have a screen to filter out the large particles that will ruin an oil pump. With a push rod going through a rocker, you may have debris clogging your pickup.

                I am not really familiar with AMC V8 engines, but you should prime the oil pump after a rebuild, and this is how I have always done it with Chevy engines.

                1. Make sure everything is together and ready for oil (Oil cooler lines are notorious for somehow not getting connected ) and remove the valve covers.

                2. Fill the oil pan with fresh oil.

                3. On a tempermental engine I have removed the oil filter and poured oil into the pump outlet as an initial prime.

                4. Using either a special oil pump priming tool, a distributor with the timing gear removed, or a screwdriver in a drill, Turn the oil pump with a drill motor until oil is visible at the rocker arms.

                5. Rotate the motor 1 complete crankshaft revolution and repeat step 4.

                6. Finish putting it together and start it up.

                I never use petroleum jelly, grease or even assembly lube in the oil pump, just too much chance of it not dissolving right away and plugging something important.


                • #9
                  I guess there are two threads on the same topic.

                  My bad...



                  • #10
                    tracraym, with an AMC you have to pack the oil pump with vasiline or grease. it's a must, not an option.

                    i looked for a long time trying to find HV pump gears and could never find them. even the guys on bulltear didn't know of any. but everyone said the only way to increase the pressure is to tweek the bypass.


                    • #11
                      Thanks Fubar, I'll write that down in case I ever work on an AMC V8, unlikely, but not outside the realm of possibilities.


                      • #12
                        My engine woe's are complete. I pulled both valve covers off to find broken rocker arms. I pulled the heads, measured and inspected stuff, put it back together and started the engine back up. It then blew white smoke everywhere. I was sucking water into the #1 cylinder. So I take the head into a machine shop and they discover the valve seats were ground to far, and left a very thin wall between the valve seat and the water jacket. All the valve seats are like this. So I pull the other head and look at it myself. I tapped the valve seat with a screw driver, and it went through! I called the shop that did the head work and their reply was that there is no warranty expressed nor implied.I will deal with them later. So here I am with an $1800 piece of junk engine.

                        So I've bought a 360 (leave these 304's while you can! Thanks for that advice FUBAR!) I'm sending it off to be remanned (with a 3 year 36,000 mile warranty). The shop will do all the mods I'm looking for while I am off to JRTC and when I return, I'll drop a fresh new 360 into my Jeep. Another $3200 later!

                        The best part is my wife is fine with it! She now is asking if we should replace the T150 with a T18. Well, if I could find one that was affordable, I would.