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    Timing Chain Guide Failure

    Hey R3V,

    I've had my 91' 318is for nearly a year now, and a few days ago it had a major mechanical problem. I was driving over an overpass when all of a sudden the motor began making a very loud noise very similar to a diesel engine.

    I shut the motor off immediately and coasted into a parking lot to have the car towed back home. First I ran a cold compression check and all the cylinders checked out at around 200 PSI. I pulled the valve cover and there was no carnage to be seen. I removed the spark plugs and didn't see any damage in the cylinders either. Later on I pulled the lower oil pan to see shards of plastic in the bottom, hence my suspicion of the timing chain guides. Ironically one of the first things I did to the car was replace the tensioner with the updated m44 part. The oil pickup was relatively clean, so I'm hoping nothing was sucked up into the motor.

    Do you guys think the motor is salvageable, or is it best to get a better condition m42 and swap it in? This motor/chassis has ~141,000 on it. I have no problem doing the timing chain kit install, but I'm also not sure if this is a common failure. Worse comes to worse the car will be 24 valve swapped, but I'd like to keep it an m42 if possible.

    What do you guys think?

    Thanks,

    Joey

    Click image for larger version

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    #2
    Before you scrap it I'd suggest removing the upper timing cover just to look around. Or if you wanted to be super lazy, just remove the valve cover and look from there, especially with an endoscope. If you see upper, and two side guides you are still good to go if you can live with bits of plastic in the engine. Of course, any guide failure probably indicates the general condition of the remaining components.

    As to the bits in the pan, it looks most like the lower guide, which is rather non-essential as compared to the rest of the guides.

    Comment


      #3
      Thanks for the response Roguetoaster.

      When I had the valve cover off, the side guides seemed to be intact, as well the guide that sits up top. Like you said, the next step is to pull the timing case off and dig in!

      Comment


        #4
        If it has good compression, I'd not scrap it just yet. Might be the timing chain tensioner
        -Christian

        '02 ///M3 CarbonSchwartz 6MT daily beast
        08/91 Mtechnic II 325IC alpine/lotus
        318iS, slow build/garage queen...
        '37 Chevy pickup, the über project
        Originally posted by roguetoaster
        Be sure to remind them that the M42 is one of the best engines ever made, but be sure to not mention where it actually falls on that list.

        Comment


          #5
          Any other M42 you find should have the timing components done anyway, so why not do yours?

          If it hasn't worn through the case yet, fix it and be happy...

          Why BMW BS'ed the M42 timingcomponents is beyond me. But they did...

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

          Comment


            #6
            Originally posted by TobyB View Post
            Why BMW BS'ed the M42 timingcomponents is beyond me. But they did...

            t
            They managed to screw up the s54 also with the vanos oil pump drive tabs ugh
            My m42 has a hole in the timing case from the the upper bolt on the intake side chain guide lol
            -Christian

            '02 ///M3 CarbonSchwartz 6MT daily beast
            08/91 Mtechnic II 325IC alpine/lotus
            318iS, slow build/garage queen...
            '37 Chevy pickup, the über project
            Originally posted by roguetoaster
            Be sure to remind them that the M42 is one of the best engines ever made, but be sure to not mention where it actually falls on that list.

            Comment

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