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Thread: Xflow scraping noise

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    Bodger

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    Xflow scraping noise

    Need some help. Got an updated 1700 xflow, 234 can, pocketed pistons, twin 40's etc. It's out of a Caterham and done 30000. It's been fine until last few days. When I rev over about 2500 I get a scraping noise. It's particularly bad when you come off the the throttle, then it's really loud. It doesn't do it at idle, just over about 2500 rpm. I've listened round the engine bay can't tell where it's from. I initially thought valve clearances but that's more of a constant ticking noise even at idle isn't it? This is more of a slow scrape as the revs drop. I adjusted them anyway to 22 & 24 as quoted by Kent for the 234, noise still there. It's like I say a tinny scraping noise most prominent in lift off. Any ideas? Thanks

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    Racer Decade Plus User rallyrob's Avatar

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    Re: Xflow scraping noise

    Are you sure it's not something simple like a pulley starting to come loose. Alternator or water pump pulley maybe...

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    Re: Xflow scraping noise

    Quote Originally Posted by upthevilla View Post
    Need some help. Got an updated 1700 xflow, 234 can, pocketed pistons, twin 40's etc. It's out of a Caterham and done 30000. It's been fine until last few days. When I rev over about 2500 I get a scraping noise. It's particularly bad when you come off the the throttle, then it's really loud. It doesn't do it at idle, just over about 2500 rpm. I've listened round the engine bay can't tell where it's from. I initially thought valve clearances but that's more of a constant ticking noise even at idle isn't it? This is more of a slow scrape as the revs drop. I adjusted them anyway to 22 & 24 as quoted by Kent for the 234, noise still there. It's like I say a tinny scraping noise most prominent in lift off. Any ideas? Thanks
    Has it got an alloy Rocker cover? If so check to see the Rockers are n't fouling the sides of the cover.

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    Re: Xflow scraping noise

    if its got a pressed steel/spot welded crank pulley it could be braking up

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    Bodger

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    Re: Xflow scraping noise

    Thanks for the replies. It's definitely not rocker cover, tried that. The car has megajolt fitted so the crank pulley is a fancy looking thing I don't really want to mess with. If I took the fan belt off and tried that just for a shirt time, so no water pump or alternator, that'd be ok wouldn't it? Let me know if it was a pulley. Cheers

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    Racer Decade Plus User rallyrob's Avatar

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    Re: Xflow scraping noise

    Yes but dont run it long. I'd check the fan blade fins on the alternator personally. They're very easily bent accidently. You can take the belt off an spin that by hand.

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    Re: Xflow scraping noise

    Quote Originally Posted by rallyrob View Post
    Yes but dont run it long. I'd check the fan blade fins on the alternator personally. They're very easily bent accidently. You can take the belt off an spin that by hand.
    I have known one of the long three bolts that holds the casing together on a Lucas alternator to work loose and catch on the alternator fan.

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    Racer Decade Plus User rallyrob's Avatar

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    Re: Xflow scraping noise

    Blimey have you.. Never heard that one, definitely feasible though.

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    Tyre Kicker briang's Avatar

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    Re: Xflow scraping noise

    I've had the front bearing of the alternator wear out causing the fan to rub on the housing.
    Brian.

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    Re: Xflow scraping noise

    Finally got round to taking the engine out today. Turned it upside down on my bench and turned the engine over by the crank and you could hear it coming from number one bore as Piston started to rise. Took the Piston and rod out and couldn't see anything. Rings and bearings all intact, bore looks ok. Don't know what it was but with this Piston now out all the others move freely with scraping noise gone.

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    Re: Xflow scraping noise

    Check the front of the sump; you may have bashed it and now the rod could be hitting at bdc.

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