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  1. #1
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    Default 76 FLH Knocking Issue

    Hey everyone, hopefully someone has some insight on an issue with a 76 FLH Shovelhead. Recently installed a Panhead Horseshoe oil tank on a 76 FLH Electric/Kickstart. Now there is a knocking that sounds like itís near the engine that comes and goes. The knocking increases when you get on the throttle. Also the nose cone gets really hot. Itís running straight drag pipes with a S&S Super E. No other modifications except the new oil tank. The engine was recently rebuilt and only has 2,000 miles on it. Anyone have any ideas?? Thanks!!

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    Quote Originally Posted by schwendy76 View Post
    Hey everyone, hopefully someone has some insight on an issue with a 76 FLH Shovelhead. Recently installed a Panhead Horseshoe oil tank on a 76 FLH Electric/Kickstart. Now there is a knocking that sounds like it’s near the engine that comes and goes. The knocking increases when you get on the throttle. Also the nose cone gets really hot. It’s running straight drag pipes with a S&S Super E. No other modifications except the new oil tank. The engine was recently rebuilt and only has 2,000 miles on it. Anyone have any ideas?? Thanks!!
    Yep did you make sure the oil was circulating????? Did you clean out the tank really good before you installed it??????
    It sounds like your bottom end is taking a shit....... Don't ride it anymore until you tear it down.......

    Best of luck but it doesn't sound good............

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    Got good return flow to the tank? No kinked oil lines/hoses?

    I wouldn't ride it until it's fixed. The problem may have no relation to the tank swap.

    To begin I'd perform a compression test and inspect the spark plugs, but Tattooo is likely correct. A teardown will cost a gasket kit and some time, but beats breaking parts. Post what you find.
    Last edited by farmall; 08-21-2019 at 3:08 PM.

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    Quote Originally Posted by farmall View Post
    Got good return flow to the tank? No kinked oil lines/hoses?

    I wouldn't ride it until it's fixed. The problem may have no relation to the tank swap.

    To begin I'd perform a compression test and inspect the spark plugs, but Tattooo is likely correct. A teardown will cost a gasket kit and some time, but beats breaking parts. Post what you find.
    Thanks guys! Let ya know what I find. 👍

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    You did put the hoses on correctly, didn't you? If your running solid lifters you could get away with it for a while without hearing anything but with hydros you would know it right away.

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    Hoses are on right. Ran a compression test and both cylinders were at 90 psi where they should be. Checked the plugs and they were good. Haven’t checked the lifters yet but I’m assuming they’re Hydros. How would you check to see if oil was flowing properly? Could the Dyna S ignition the previous owner put in be going bad? Causing knocking? Also the cone gets crazy hot.

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    Quote Originally Posted by schwendy76 View Post
    How would you check to see if oil was flowing properly?
    Take the cap off and look inside it's real easy.....

    Quote Originally Posted by schwendy76 View Post
    Could the Dyna S ignition the previous owner put in be going bad? Causing knocking?
    It's not likely..............


    Like I said don't ride it any more until you find the problem....

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    Why not drain the oil and cut open the oil filter (If it has one) and look for shiny shi .... stuff ... !!!
    If the rod bearings are bad enough to be able to hear a knock, should see cuttings in the oil...

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    The hot cone cover would have me pulling it for inspection and because chips tend to accumulate in the bottom of timing chests on their way into the oil pump.

    Was the throttle plate held fully open during the comp test? I'd expect higher from such a recent rebuild.

    Andrews static compression reference: http://www.andrewsproducts.com/sites.../page_17_0.pdf

    Image from HD factory service manual which really should have been more precise:
    Attached Thumbnails Attached Thumbnails comp test.jpg  
    Last edited by farmall; 08-22-2019 at 2:00 PM.

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    S76,

    As Tattooo mentioned above, I hope for your motor's sake that the oil tank was clean, clean, clean before you installed it. New or used, does not matter. If you have let a dirty oil tank escape your notice, swarf has probably been pumped into your fresh motor, and that ain't good.

    But, if the tank and oil were clean, a restricted feed to the pump or incorrect line routing will mean no or low oil pressure, and if you have hydraulic tappets, you may only have a collapsed tappet causing your knocking. (They can clatter pretty loud.)

    The hot cam cover does concern me, although they do get pretty hot this time of year. You must have noticed that it was unusually hot, since you bothered to mention it.

    Do you have an oil pressure gauge or indicator light? What are the readings? This is one time a gauge would be handy for diagnostic purposes.

    Good luck with this, I hope it will be an inexpensive fix.

    Jim

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    Quote Originally Posted by JBinNC View Post

    As Tattooo mentioned above, I hope for your motor's sake that the oil tank was clean, clean, clean before you installed it. New or used, does not matter. If you have let a dirty oil tank escape your notice, swarf has probably been pumped into your fresh motor, and that ain't good.

    Jim
    He never answered that question I asked......

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    Quote Originally Posted by Tattooo View Post
    He never answered that question I asked......
    ....so I observed....

    Jim

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