Announcement

Collapse
No announcement yet.

Major valve train noise after M42 head rebuild

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

    Major valve train noise after M42 head rebuild

    Hate for this to be my first post. Currently working on a 91 318is

    To make a long story short I recently had to take my head to a machine shop to have a corroded coolant nipple replaced. Got everything back together now there's horrible sounding obnoxious valve train KNOCKING. Tapping would be a complete understatement, I'll get a video up soon.

    I'm now in the process of taking the lifters out to soak them in oil, something I didn't do before. Any input or suggestion in the mean time would be much appreciated.

    #2
    Double check the timing. A decade or so ago I rebuilt the timing chain assembly on an M42 and had things off by 2 teeth and had what sounded like awful lifter noise. It was pistons and valve heads kissing. Thankfully the hydraulic lifters have some capacity to absorb the impact and after getting stuff properly aligned, all was well.

    To get the pistons to TDC, I usually stick a metal rod down the spark plug hole for cylinder 1 and mark the heights for TDC and BDC. Then I use calipers to measure when the piston is 81mm higher than its lowest point, which puts it at TDC.

    For the cams, I use a metal block to get the square ends by cylinder 4 to be perfectly parallel. Some zip ties and crescent wrenches hold things in place. The lobes for cylinder 1 should be pointing up and inward. The cam gears should have the bolt heads centered in the slots (assuming that this is a stock engine).

    The tensioner piston can be in, but unthread the cap most of the way to release much of the force on the guide rail. Get everything aligned, bolt the cams to the sprockets, tighten the tensioner piston cap and turn the engine manually with the crank bolt. ONLY turn it clockwise (as seen from the front of the engine). After a couple of revolutions, double check that everything is still in TDC alignment, and adjust if needed.

    Transaction Feedback: LINK

    Comment


      #3
      That sounds like what it might possibly be but the chain was zip tied to the sprockets when the cams came out so there's no way the teeth are off. Being adjustable cam gears, the cams or the sprockets seemed to be off a few millimeters where they bolt together judging by the original marks the bolts left from being on so long. Not sure if that small of a difference would be causing this though. When I put everything back together I'll get them where they originally were.

      Comment


        #4
        Here's a video of the horrible noise

        E30 1991 BMW 318is major valve lifter noise after cylinder head rebuild

        Comment


          #5
          Take your valve cover off and triple check that everything is in alignment with the crank wheel at the TDC mark.

          Also make sure that when the mark is aligned that you are actually at TDC and not 180 over with a screwdriver or similar.

          I'd be surprised if you are all in time, but if you are check your plug wire order.

          Comment


            #6
            I have the alignment tool if you need to borrow it.

            Comment


              #7
              OP make sure your cam gears are dead center in the middle of adjustment. If you have an intake or exhaust cranked all the way to one side youll get noise. Ive found with some of my engines if you advance or retard the cams it will cause chain noise. It may be because of a worn chain and the adjustment causes slack on the opposite side of the tensioner.

              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


                #8
                So the lifters are out and it seems two or three of them are bad, I'm able to compress them by hand, the rest are solid. Is there a way to possibly fix them or am I better off getting new ones?

                And thanks btw for the info I'll be sure to have the cams in the dead center of adjustment, it looks like that's how they were originally judging by the marks that were left.
                Last edited by mclaaron; 09-20-2015, 12:08 AM.

                Comment


                  #9
                  sometimes the lifters need to pump up. Did you soak them all in oil before putting the top end back together?

                  You may have been able to get away with revving the engine to build oil pressure and pump the few lifters up.

                  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


                    #10
                    They are sitting in oil right now but unfortunately I wasn't aware beforehand that they should have. I was thinking the same thing but the noise and engine shaking was so bad that I didnt want to risk damage. Not sure if you had a chance to watch the video clip I posted but it's pretty bad even worse in person. Sounds like a previous post said that a valve may be kissing a piston. Looking further into it I was informed that some of the lifters may not be bleeding down causing the valves to stay open longer than they should.

                    Comment


                      #11
                      It can take FOREVER for the lifters to pump up if they aren't pre- soaked, and even a
                      very long time if they are-
                      mine sounded awful for about 10 minutes when I did it. Been fine ever since...
                      And yes, it took a while running at 2K+ to get the worst of the noise to settle down.

                      I'm guessing you made sure you have oil pressure- I had a problem with
                      the oil pump losing prime when I did the oil filter housing gasket.

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

                      Comment


                        #12
                        Originally posted by TobyB View Post
                        It can take FOREVER for the lifters to pump up if they aren't pre- soaked, and even a
                        very long time if they are-
                        mine sounded awful for about 10 minutes when I did it. Been fine ever since...
                        And yes, it took a while running at 2K+ to get the worst of the noise to settle down.

                        I'm guessing you made sure you have oil pressure- I had a problem with
                        the oil pump losing prime when I did the oil filter housing gasket.

                        t
                        I let it idle and even rev'd it for quite some time, still no avail. It's looking like I'll be getting 2 new to replace the shot ones.

                        As for the other ones, I was told to bleed them out before reinstalling since I don't have the order they were originally in. Anyone have experience getting the oil out of these lifters?

                        Comment

                        Working...
                        X