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Washer in my oilpan?!

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  • Washer in my oilpan?!

    I dropped the oil pan today and found an M6 washer, not the wave kind that is used on all the oilpan fastening bolts, but a thick one. Where could of that came from?? Also, how much tension should there be one the oil pump chain. The manual states that the chain should give in the middle under small pressure from my finger. I'd expect someting more specific from bmw... Any ideas?

    Thanks, Nik

  • #2
    No one seems to be weighing in so I will try.....

    The timing chain I think is generally loose on any cars that have been run much at all. I would shim it to take out the slack but without it being "tight". You can tell how tight it is by grabbing the chain where it is on the sprocket, and "jiggling" it front to back. If it won't move slightly on the sprocket it is very tight, probably too tight. This should allow, ideally, about 2-5mm of movement if you push on the chain with LIGHT pressure in the middle where it is unsupported.

    I think the BMW direction about measuring give in the middle of the chain sucks, because it all depends on how much you push on it. You can shim the chain very tight and you will still get some give in the middle.

    As far as the washer.......

    I am thinking back to assembling my engine and I can't think where the washer could have come from. The only internal engine fasteners I can think of are all "critical", in that if one of them had loosened and lost a washer you would definitely know it. IIRC there is at least one M6 washer that goes under the studs that the timing chain guide attaches to. If one of those had backed out, there is a chance the engine would keep running and not "blow". This is also a likely candidate because the stud would probably stay attached to the chain guide by snap ring and drop the washer. In any other instances you should have a washer AND a bolt in your oil pan.

    I think all the other washers, such as the ones on the oil pan baffle/windage tray bolts and the valve cover tray are all "captive", in that they would stay attached to their bolts if the bolt backed out.

    I think it is safe to say, that this situation is NOT good and you need to get to the bottom of it before driving the car around. Like I said, everthing inside the engine is pretty critical, and there is also a good chance there is a bolt floating around unaccounted for in your engine.

    Last edited by Ironhead; 07-20-2004, 11:22 AM.