loud knock cylinder 1

Thread in 'Technical Questions' started by TYSON, Jul 13, 2011.

  1. TYSON

    TYSON Member

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    evening all
    after snapping a cam on my rb20e and replacing the head it now knocks/taps horribly on cylinder 1
    it also misfires when you rev it so I re checked the timing but it all seems good. the bottom end all seemed fine as well prior to putting the engine back together.
    Unfortunately there are no timing marks on the head of an rb20e other than on the cam wheel so I set the bottom end to tdc and the cam with the dot at the top with the cam about to open the exhaust next. I cant find any links and I even swapped over the rockers from the old head as the new head had a bit of play. The new ones sorted this but on restarting the engine aaah its horrrrible.
    before I rip the thing apart any ideas would be great

    cheers

    ps this is a learning curve for me so im not taking the easy route of chucking a decent engine in just yet :wack:
     
  2. Dex

    Dex kut!

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    bent valve?
     
  3. bodgeabit

    bodgeabit Member

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    compression test will reveal bent valve as above ,if you keep running it ,It will be damaging your piston if it isnt f.... already !
     
  4. Swampy442

    Swampy442 Active Member

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    Next time, leave it to an expert
     
  5. HermaN

    HermaN Member

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    If it's his own engine and he wants to use it as a learning curve (at his own risk), then why should he "leave it to an expert"??

    End of the day, all the professional engine builders out there started somewhere, they were not born with all the knowledge they currently have.

    Anyway @ the OP, do a compression or leak down test and take it from there.
     
  6. Dex

    Dex kut!

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    AND its a rb20e lol. i mean come on haha
     
  7. TYSON

    TYSON Member

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    spot on herman. I want to make my mistakes on this engine first and learn from it which I have, a lot. Im not being tight by not paying an expert, just love engines and learning. If the engine dies I am not fussed as long as it wasnt a stupid mistake as its only an rb20e.

    Any ho misfire was due to the injector which I swapped out so thats one less thing to worry about. I have compression tested it, reads 155psi. Its really bugging me now as I dont want to take the head off unnecessarily but admittedly I am out of ideas now. Sounds like one of the tappets need adjusting but this isnt possible (I dont think). Searched high and low for info on the rb20e but cant find anything useful.

    Think I am lost because I dont know why the cam snapped as it took a beating at pod no trouble and I was only poodling along at the time it failed. Also the head seems so basic that I cant see what it could be. as mentioned before after first hearing the tapping and seeing loose rockers I swapped them with the ones from the old head as they were great before but it made little differance if any.

    thanks again for the pointers most appreciated
     
  8. robinpipers

    robinpipers Member

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    pour a little oil into the cyl and see if the compression rises, if it doesnt then u prolly have a leaky exhaust valve... what is the compressions on your other cyls? cus aslong theres not to much difference between the highest and lowest your pretty fine. i think 10% is ok that means 200psi on top and 180 on lowest or such.

    but as ive just notice u mentioned loud knock on cylinder one. u didnt have any marks in your piston on cyl 1 right. are ur sure ur rod bearings are ok?
     
  9. TYSON

    TYSON Member

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    had great fun dismantling the engine today. Found a few tiny metal particles along with a mildy scored big end bearing on cylinder 1. I dont think this would cause the loud tap?! so think could be blocked oil gallery. Going to clean the head tomorrow, put it on the other bottom end and hopefully she will purr into life. Cheers for the info
     

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