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Suction from bellhousing*Fixed*

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    Suction from bellhousing*Fixed*

    I have spent about a week googling, searching all forums with M/S5x knowledge and can come up with nothing. Here is what's up.

    Car: 86 325es with 94 M50tub25, ZF trans, M20 shaved flywheel with clutchmaster stage 2 clutch.

    Issue: while driving along on a normal day, the car suddenly lost power and stalled out as if there was a new vaccum leak. There was an extremely loud air noise coming from the bottom exhaust side of the motor. After exhausting many other ideas, used a piece of paper to test for exhaust leaks. The piece of paper was sucked onto the side of the transmission where it mates to the motor.

    Attempted fixes: Smoke test revealed a few small vaccum leaks. Fixed stripped valve cover bolts, snapped timing cover stud, replaced dipstick tube o-ring, replaced cam sensor o-ring. All of these were leaking oil as well.

    Our only thought - the rear main seal was installed incorrectly and with the vibration caused by the poly mounts, it may have worked itself out. There was a high pitched whistle coming from the trans area that had developed a few weeks prior. The main reason I am reaching out here is that in order to drop the trans, obviously the subframe has to drop or the motor has to be pulled and right now, I am on shop time since we are waiting to close on our new house and I have no garage.


    Thoughts are appreciated, experience with a similar issue is much welcome. Thanks in advance.

    After fixing a lot of other small things we finally found the issue. Embarrassing as it may be, the cat was 100% clogged. Turns out the shop that installed it put it in backwards. Since it only had 3000 miles on it, it wasn't something we even thought about. I just went ahead and pulled the trigger on a new exhaust system and will be deleting the cat in favor of a resonator.
    Last edited by BoxDriver86; 06-30-2015, 06:14 AM.

    #2
    Wait why does the subframe to drop to get the trans out? Should be able to pull it without doing all that.

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      #3
      Originally posted by mpowerful View Post
      Wait why does the subframe to drop to get the trans out? Should be able to pull it without doing all that.
      I know most cars are different on this, but I have not had access to the upper trans bolts since I first did the swap. I have had to pull the trans before since I used the wrong TOB and that was the only way to get it out.

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        #4
        Can you not get at the bolts by lowering the back of the transmission via disconnecting the driveshaft then taking the tranny crossmember off?

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          #5
          We're going to try and lower the subframe just enough to get to it without dropping it all the way. It didn't work last time but we'll see. I'm not sure if it's because we're using the AKG mounts, my car is jacked up from previous damage or if there is another reason.

          I'm bummed that no one else has had this issue before. I really want to get some piece of mind before digging into this thing. After reading on other forums (not BMW related) of air sucking past a bad rear main, most people say that the sound goes away when the oil cap is removed, which is not the case here. Totally stumped on this one.

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            #6
            I have an s5x w. zf 310 akg eng mounts. I removed trans by using an engine support bar across eng comparment, loosening eng mounts put a jack under rear of eng , remove trans mount let eng, rock back to firewall. tool of choice here is a 36" long extension made for trans removal. usually 1/2 fem x 3/8 male universal join w/ socket. A pry bar can be used to flatten the heat shield on trans tunnel
            My CA legal M60 swap

            The happening in our garage

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              #7
              What happens when you remove the oil cap? Anything? Nothing happens with my S50 and I have read that it is normal and not normal. My S50 runs like a champ and pulls like a freight train.

              In other words, removing the oil cap might not necessarily be an indicator.

              Comment


                #8
                Originally posted by M3PO View Post
                What happens when you remove the oil cap? Anything? Nothing happens with my S50 and I have read that it is normal and not normal. My S50 runs like a champ and pulls like a freight train.

                In other words, removing the oil cap might not necessarily be an indicator.
                You know, since the swap it's been like that for me. Pull the oil cap and no change. In my old e36 m3, i once left the oil cap off after and oil change and it ran like ass. I just assumed that I still had vacuum leaks on this one until they were sorted. The main point was to see if the air noise went away or diminished when vacuum was introduced elsewhere in the system.

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