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Turbo M20B25 Engine Noise

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    #1

    Turbo M20B25 Engine Noise


    I have a 89’ 325i with a T3 turbo. Currently running MSPNP2. Car was tuned. Over the last few weeks I’ve developed engine starting issues and at one point ignition issues when in boost. She builds 10lb of boost. I pulled and replaced the plugs with NGK7R and gapped them to .22 and that seemed to eliminate my sputtering at high rpm. Again, I’ve developed and still have an issue with the engine starting without pumping the pedal. This may or may not be a symptom of my bigger issue. I took a friend for a ride the other day and was doing some

    pulls. On the way back in 2nd gear no boost as I went to turn into my neighborhood it developed a knock/tapping noise. Since then I’ve adjusted the valve lash to .25. I’ve also noticed that the oil crossover tube doesn’t spray evenly. Head was machined and all new cams rockers springs etc installed and it’s less than 150 miles on them. I’ve uploaded a YouTube video. My next step is a leak down. I feel but not entirely certain it could be a vent valve although it doesn’t quite sound like it. Really not sure what else it could be. Changed the oil and filter no metal shavings in my pan.
    ​
    https://youtube.com/shorts/zFLOGWalM4g?si=Xo2Kl0dlbI4q302c
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    #2
    Well, that's def internal noise you got there.. If I were to guess, it sounds like an eccentric is not adjusted correctly, has a massive flat spot, our your .25, which I'm going to assume is metric, wasn't done correctly.

    take the cover off and check each rocker by feel to make sure one isn't wildly off..

    I also dont think this noise has much to do with the rest you said.
    Current Collection: 1990 325is // 1987 325i Vert // 2003 525i 5spd // 1985 380SL // 1992 Ranger 5spd // 2005 Avalanche // 2024 Honda Grom SP // 2024 Yamaha XSR700 // 2024 Jeep Gladiator Rubicon

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      #3
      I’ll double check it again. I adjusted each valve one by one in firing order making sure each valves line was pointing downwards.

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        #4
        ...also check your cam lobes-

        if you wipe a cam, it makes pretty much that sound...

        having done so myself back in the 'oops no zddp here now' days.

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

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          #5
          I agree it sounds like a valve adjustment issue. In the past I had a valve where the top was mushroomed, although I could get it in spec by a feeler gauge it never sounded quite right. So I'd inspect the valve tops too. Also, sometimes an exhaust leak can sound similar to that and might make sense on a fresh build especially as you're starting to put heat into a new(?) turbo manifold.

          For your ignition break issues, cap and rotor should be okay for 10 psi IF it's fresh. I think you're just starting to deal with teething issues of honing in a turbo setup. Tackle each issue one at a time, I think they're all separate issues.

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            #6
            I’m almost about to pull the engine. I’ve adjusted the valves too many times to count now. I do think there is an oil issue. Not sure as I don’t have another m20 to compare to. There is an abundance of oil in 3&4 but 1,2,5,6 are not lubed much at all. The crossover oil tube barely drips and when that’s not installed, no oil comes out of the threaded ports the crossover tube threads into. Installed new rocker shaft retaining clip as the last one was bent. I think I have an issue at the top of a valve.
            https://youtube.com/shorts/9hpAdXwxFtQ?si=_7oEEnNfAVyc3d-J


            https://youtube.com/shorts/zjmtf69S4FA?si=Cp7duB0if21Pycrr

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              #7
              If it was an oil issue the, multiply the tick x6. It sounds like one rocker is making the noise. I had a the same tick on a high mile M20B27 eta and just kept driving it. The tick I had was coming from #1. Surprisingly, it ran really good. I knew the issue would require removing the head because visually all looked well. I would start testing valve springs, measuring and inspecting rockers. Pulling the engine would be a lot of work as compared the cyl head.

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                #8
                see if you can clean up the oil bar to get better oiling on the head. it's been known to lead to cam problems.

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                  #9
                  I did clean the oil bar and it still comes out the same

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                    #10
                    Originally posted by jbontke View Post
                    If it was an oil issue the, multiply the tick x6. It sounds like one rocker is making the noise. I had a the same tick on a high mile M20B27 eta and just kept driving it. The tick I had was coming from #1. Surprisingly, it ran really good. I knew the issue would require removing the head because visually all looked well. I would start testing valve springs, measuring and inspecting rockers. Pulling the engine would be a lot of work as compared the cyl head.
                    It does sound like cylinder one. I still haven’t pulled the motor. Might just start with the top while it’s still in the car
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