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  1. #1

    Default 1990 Evo Oil Pump Issues

    Trying to figure out just what is going on.

    Just built a rigid Evo (1990 FLH) chopper, put everything together, wiring is fine, mounts are flush, everything is aligned as far as the drivetrain. But we’ve ran into an Oil Pump issue.

    For some reason my oil bag isn’t getting any oil back on the return, so no oil flow at all. It feeds to the oil pump, and I have pressure within the cam chest (only about 30psi), but my oil lines to my filter are dry bones, and my pushrods are just as dry. I primed the oil pump as well.

    Before this, we pulled the pump apart and noticed one key was sheered and replaced it, but it had a bit of lash with the replacement? And the oil seal for the rod itself seems not super tight but not enough to leak oil. Gaskets are seated fine, everything is torqued to spec.

    I guess my question is could the Breather gear being not on time have something to do with no pressure for the return? Is it the oil pump with the possibility of that key being sheered because of the little lash it had? Or is it the oil seal for the rod itself?

    Pulling at straws here I know but any help would be great. Thanks guys.

    UPDATE: smoothed out the chatter marks, replaced woodshaft key for the return, and ended up using the stock oil pump which is working fine. Thanks for the help y’all. Bitch is up and running.
    Last edited by HaggardnShoved; 08-11-2020 at 2:51 AM. Reason: Update

  2. #2
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    You have described two different problems.

    If the oil pump is not returning oil, that usually means the return side key is sheared. You could also have a pump body that is damaged on the return side, and that is likely if it had a sheared key when you took it apart. Replacing the pump is the only fix for that.

    If you have oil pressure indicated, and you say your pushrods are dry, that doesn't make sense. On an evo, the tappets, and then the pushrods, are the first to get oil pressure in the system. Do you mean that the oil is not being transferred up the pushrods to rocker arms, or are you just looking at the pushrods with the pushrod tubes collapsed? It takes a little time for the oil to go up through the pushrods and reach the rocker arms.

    It's good that you are checking your oil system carefully. You will need to pull the oil pump and inspect it again, and I suspect that damage will mean a replacement is needed. Some pictures of the return side of the pump body would be helpful when you get to it.

    Jim

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    parts image of a factory pump for a '91 FLH that may be helpful...is yours a factory pump?

    Click image for larger version. 

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    https://partsfinder.onlinemicrofiche...)%20OIL%20PUMP

  4. #4

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    JB

    When I pulled the oil pump I noticed chatter marks and indentations in the metal where the gears go, luckily the shop I’m doing it in had a used replacement with minimal wear on it. When I went to put it all back together, one of the woodruff keys, specifically the return gear key, had a bit of lash on it, on top of that, the seal that sits on the rod was not super tight. Thinking it was okay I put it all together.

    The Tappets have a small amount of oil in the bottom of them but the rods themselves are very dry. And the rockers are not getting oil. I’ve only been running it for about 30 seconds at a time and cutting it since I’m not seeing return flow. I’ve maybe started it 3 times since I don’t want to blow out the engine.

    I’ll get pictures tomorrow when I sit down at it again.

  5. #5

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    TriNortz

    My oil pump is an aftermarket by V-Twin MFG, and yes similar in build. The #27 gear had slight lash with the woodruff key. The #15 seal is the one that isn’t super tight, but tight enough to hold a seal in my opinion.

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    Quote Originally Posted by HaggardnShoved View Post
    JB

    When I pulled the oil pump I noticed chatter marks and indentations in the metal where the gears go, luckily the shop I’m doing it in had a used replacement with minimal wear on it. When I went to put it all back together, one of the woodruff keys, specifically the return gear key, had a bit of lash on it, on top of that, the seal that sits on the rod was not super tight. Thinking it was okay I put it all together.

    The Tappets have a small amount of oil in the bottom of them but the rods themselves are very dry. And the rockers are not getting oil. I’ve only been running it for about 30 seconds at a time and cutting it since I’m not seeing return flow. I’ve maybe started it 3 times since I don’t want to blow out the engine.

    I’ll get pictures tomorrow when I sit down at it again.
    Thirty seconds at a time is not enough time for it to lift oil through the pushrods to the rocker arms, so you are probably OK on that. And that is why they make assembly lubes.

    The same may be true of the return. I have seen it take a minute or more for oil to start returning at the tank when firing a fresh motor, even with a pint or so of oil in the flywheel cavity.

    In my experience, some of the aftermarket pumps are really bad, poor machining and poor tolerances. If it is a Sifton pump from V-Twin, it is best to install it in a trashcan. Sorry, just the way it is. The Ultima pumps from Midwest seem to be serviceable and of course my go-to pump is S&S and money well spent in my opinion.

    Jim

  7. #7

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    Okay, the engine has been sitting for 3 years or so. The flywheels have some oil in it, I checked for that as well. Should I fill the lines with oil as well as the filter or should I allow it to push it all through? I’ve heard two trains of thought in it so more input is great. Just trying to figure out if there needs to be oil in there to help push the lines or if it should pick up on its own. Should the return have some type of pressure coming out of the nipple without the line on?

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    As long as you prime the feed side, and you did, because you have oil pressure, you are OK. The return side will take care of itself as soon as enough oil accumulates in the cam chest to cover the return passage to the pump.

    You have oil pressure, so I would run it for a minute or two (don't let it get hot) and see what happens.

    Jim

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    your problem is the V-Twin mfg oil pump...
    Tiawan ted only sells shit, made in the gutters with hammers by 11 year old kids...
    fuck all he sells is worth fitting let alone an oil pump !!! the heart of your motor....
    throw it away & get an S&S oil pump....
    S&S make about the best oil pump for the money out there & well worth getting if ya think what it does & what it looks after for you...
    seriously... if you want your bike to last... get rid of any of his crap & get genuine HD or a GOOD quality after market part & do not THINK buying his shit is a way to save... it ain't & will bite ya ass big time

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    Quote Originally Posted by tzienlee View Post
    your problem is the V-Twin mfg oil pump...
    Tiawan ted only sells shit, made in the gutters with hammers by 11 year old kids...
    fuck all he sells is worth fitting let alone an oil pump !!! the heart of your motor....
    throw it away & get an S&S oil pump....
    S&S make about the best oil pump for the money out there & well worth getting if ya think what it does & what it looks after for you...
    seriously... if you want your bike to last... get rid of any of his crap & get genuine HD or a GOOD quality after market part & do not THINK buying his shit is a way to save... it ain't & will bite ya ass big time
    Well, there is that.

    Jim

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