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Another "what's this knock" thread, sorry in advance

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    Another "what's this knock" thread, sorry in advance

    I know these questions come up all the time, sorry. I have done a fair amount of searching over the last few days and haven't really found anything exactly comparable. I did find a video that sounded very very similar to the initial knock which actually came from a thread here previously but I can't seem to find that thread at the moment. Here's that video of someone else's car, I'll link the thread if I find it:
    Started happening to my e30 a few days ago, it's a super loud ticking/knocking noise in the head, it's not valve adjustment, I've adjusted it twice already a...

    No definite resolution on that car so maybe the thread itself is somewhat irrelevant.





    After a week or two of having the e30 running on megasquirt (and some hard driving as a result) I suddenly developed a knocking from the front of the motor:




    Top end was suggested and since it's the easiest I went ahead and adjusted the valves this afternoon. They were definitely way off and I have no idea when this was last done as I've only had the car since September. The previous owner claims to have done a head gasket and judging by how clean the head itself is I'm inclined to believe him.






    That makes me skeptical that this is top end related but I suppose I don't know the condition of any of these parts or the history of the motor.


    Here's how it sounds after the valve adjustment:




    It's definitely a lot better and for the first 20 seconds I ran the car I thought it was fixed.. and then it came back. I know the M20 is described as a noisy motor but I don't think it's supposed to sound like a diesel.





    One of the rocker clips is pretty loose towards the rear of the motor but the noise is coming from the front so I'm not worried about that at the immediate moment but will certainly address it.




    Any thoughts here? I'm going to continue looking into m20s with failing rod bearings to see if I can find a similar condition.




    Also somewhat worrisome in regards to the crank: when pulling the plugs to make the crank easier to turn I noticed that bank 1 has been running richer than bank 2... would this then create some sort of variance in thrust between cylinders that would be problematic for the crank? When I got the megasquirt running originally I wasn't getting fuel on bank 1 at all so I know this is megasquirt related but again not primary concern at the moment.
    Last edited by hotsaucewizard; 02-21-2019, 05:37 PM.

    #2
    Admittedly, I've never adjusted valves before so I suppose it's possible maybe I just didn't get it quite all the way there but I generally "know what I'm doing" with tools. But I understand that it's sometimes hard to know if you've done something right if you haven't already done it a few times.

    The first rocker's gap was way too tight before I adjusted it and although I had a bit of frustration with trying to decide exactly how much drag on the feeler gauge was enough I read online to err on the side of not enough so I tried to be as gentle as possible about it. Judging by how drastically the noise was reduced I'm wondering if pulling the gap back even further would help remove the noise but I'm skeptical

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      #3
      hows the timing? maybe valve train is worn.
      what kind of oil you running? hope not some 30 weight oil

      Comment


        #4
        To me there's nothing worse than an unresolved forum question when you're desperately googling


        I pulled the motor and pulled it apart.. turns out the timing between head and crank was off by one tooth.. I wouldn't have thought that would be able to cause such damage but here we are..


        No worries, the plan is stroke and boost either way :)


        Comment


          #5
          I'm surprised it ran so smoothly (and revved so smoothly) with a tooth off.

          Opinions may very - but honestly, I wouldnt think you would have to replace the engine - or change pistons.

          Id prolly just grind off any loose debris on the cut on the piston(s). Have a machine shop check to make sure valves (or valve) are straight and or need replacing.

          Put the head back on - make sure the belt is on correctly and off you go..

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