Announcement

Collapse
No announcement yet.

m42 has no oil pressure

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    m42 has no oil pressure

    Hey guys, I picked up a '91 318i sedan a few months ago. It had been sitting for a while and was destined to become a swapped track car. The owner decided to sell instead. I picked it up and have been trying to revive it. After towing it home, I jumped it off and it fired right up. However, there is no oil pressure. It sounds terrible, like no oil is getting to the top end.

    I dropped the lower oil pan and of course found some bolts lying in the pan. I put those back in and tightened the other bolts holding the upper pan to the block. After that, I put the oil pan back on with a new gasket and put in the new oil and filter. Also, poured some gear oil straight into the oil filter housing to prime the engine. The engine started and sounded exactly the same.

    I currently have both lower and upper pans pulled and have taken out the pressure relief valve. It seemed ok. There is some wear on it but nothing major. It wasn't stuck either. It took some persuading, but I was able to pull it out with a magnet.

    Is there anything else I can do? I was thinking of updating to the new pressure relief valve but it seems like I'd be throwing money at a trashed engine.

    Any other ideas?

    Thanks in advance.
    '90 325i - 5 speed coupe
    '05 330ci 6MT ZHP

    #2
    lifters could be not pumping up. Is oil getting to the top end? If so id run it for a while even tho it sounds like shit. See what happens. The lifters can take quite some time to pump up especially if the engine has been sitting for a long time

    Turbo M42 Build Thread :Here
    Ig:ryno_pzk
    I like the tuna here.
    Originally posted by lambo
    Buttchug. The official poster child of r3v.

    Comment


      #3
      I ran it for a good minute or so. I took the oil cap off and it seemed like there was no oil flow in the top end

      Sent from my XT1058 using Tapatalk
      '90 325i - 5 speed coupe
      '05 330ci 6MT ZHP

      Comment


        #4
        Originally posted by Codym42 View Post
        I ran it for a good minute or so.
        Ohh, ouch. Not good. On top of that, who knows how long the PO ran it. Probably time to swap in a new engine. If you're really into saving the engine, drop a main and rod bearing cap from the bottom of the engine and see if they're trashed, but it's probably done. Also check the oil pickup gasket.

        IG @turbovarg
        '91 318is, M20 turbo
        [CoTM: 4-18]
        '94 525iT slicktop, M50B30 + S362SX-E, 600WHP DD or bust
        - updated 1-26

        Comment


          #5
          Originally posted by varg View Post
          Ohh, ouch. Not good. On top of that, who knows how long the PO ran it. Probably time to swap in a new engine. If you're really into saving the engine, drop a main and rod bearing cap from the bottom of the engine and see if they're trashed, but it's probably done. Also check the oil pickup gasket.
          Yeah, probably not the best thing to do but I've seen people having a tough time getting these engines primed. I figured if it didn't prime then, it probably won't ever. That, and I found bits of metal in the oil pan which isn't good anyway.

          It's probably done for but I really want to know why there's no oil circulating. I'll take another look at the oil pickup gasket. I didn't pay much attention to it.
          '90 325i - 5 speed coupe
          '05 330ci 6MT ZHP

          Comment


            #6
            Trouble getting them primed? I don't know. My M42 had oil pressure within a couple of seconds of starting after sitting drained for months.

            IG @turbovarg
            '91 318is, M20 turbo
            [CoTM: 4-18]
            '94 525iT slicktop, M50B30 + S362SX-E, 600WHP DD or bust
            - updated 1-26

            Comment


              #7
              I had trouble with priming when I did the head and oil filter housing together.

              If the pan loosened up, the intake passageway could have opened up,
              and worst case, a chunk of gasket come out of it. It'd then suck air,
              and never prime. But then, I'm a doom- and- gloom sorta guy.

              I had to crank the engine, plugs out, for a while with the filter housing off.
              Then install the housing, and get IT to prime, then add filter cover, and get THAT
              to prime. Then it built pressure. But not before.

              That said, the lifters, if allowed to suck air, will rattle for a LOOONNNGGGGG time sometimes.
              I'd put an oil pressure gauge on it first, to see if it really has any pressure at the bottom end.
              Then go motor shopping.

              t
              now, sometimes I just mess with people. It's more entertaining that way. george graves

              Comment


                #8
                Are you sure that the timing is set properly? If the timing chain is off by a couple of teeth, you get pistons contacting valves and the noise can definitely be confused for dry lifters. Maybe the PO messed that up?

                Otherwise, yeah, get an oil pressure gauge on there. Does the oil light stay on in the instrument cluster?

                Transaction Feedback: LINK

                Comment


                  #9
                  Thanks for all the responses.

                  Originally posted by bmwman91 View Post
                  Are you sure that the timing is set properly? If the timing chain is off by a couple of teeth, you get pistons contacting valves and the noise can definitely be confused for dry lifters. Maybe the PO messed that up?

                  Otherwise, yeah, get an oil pressure gauge on there. Does the oil light stay on in the instrument cluster?
                  I hadn't thought about that. But I'm pretty sure there's no oil circulating. The oil light on the cluster does stay on.
                  '90 325i - 5 speed coupe
                  '05 330ci 6MT ZHP

                  Comment


                    #10
                    Originally posted by TobyB View Post
                    I had trouble with priming when I did the head and oil filter housing together.

                    If the pan loosened up, the intake passageway could have opened up,
                    and worst case, a chunk of gasket come out of it. It'd then suck air,
                    and never prime. But then, I'm a doom- and- gloom sorta guy.

                    I had to crank the engine, plugs out, for a while with the filter housing off.
                    Then install the housing, and get IT to prime, then add filter cover, and get THAT
                    to prime. Then it built pressure. But not before.

                    That said, the lifters, if allowed to suck air, will rattle for a LOOONNNGGGGG time sometimes.
                    I'd put an oil pressure gauge on it first, to see if it really has any pressure at the bottom end.
                    Then go motor shopping.

                    t
                    Holy crap, what a pain in the ass.
                    '90 325i - 5 speed coupe
                    '05 330ci 6MT ZHP

                    Comment


                      #11
                      OK yeah sounds like an oil circulation problem, not timing.

                      A few people on here have had a nightmare of a time getting the oiling system to prime (Vivek is the other member that comes to mind...he probably ran the engine for a few full minutes in his attempts to get the oil flowing). Hopefully someone else here who has encountered this has a clever suggestion, other than removing the timing case to pack the pump rotors with heavy grease.

                      My own assumption is that it must be due to worn-out pump rotors that aren't sealing super well, or maybe they were manufactured to a looser tolerance or something (since they are oil pump rotors, I would not expect all that much wear on them!). One guy who has built all sorts of engines has said that it is fairly common to need to pack a rebuilt oil pump with heavy grease to get it to prime, so maybe I have just been super lucky all these years. It sucks that the M42's oil pump is so insanely inaccessible though...

                      Transaction Feedback: LINK

                      Comment


                        #12
                        My m42 tics a lot on cold starts (its a lifter). Since you can't seem to get oil visible in the top end, then the lifters sound like the problem as a result of the oil pressure problem, but like said above, timing can cause this to happen, but will usually bend a valve. i have seen the wrong plugs stick out a little too far and tap the piston lightly but thats really unlikely.

                        Comment

                        Working...
                        X