Top of Oil Pump Drive Shaft Broke
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Top of Oil Pump Drive Shaft Broke

  1. #1
    Member jetsonly's Avatar
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    Default Top of Oil Pump Drive Shaft Broke

    Lost oil pressure in my BBC 454 and fortunately caught it quick. Pulled distributor and can see the top of the shaft broke off into 2 pieces. Found 1 side with magnet. Can't get the shaft out with the magnet. I can turn it back and forth a little which leads me to believe the Mellings HV77 oil pump didn't seize. I used the hardened shaft that came with the Mellings pump. I built the engine with marine specs and this season was running Kendall 20w-50, other seasons ran straight 50w and will go back to straight 50w.

    Engine has been running fine for about 6 years. Turns 6000-6200 rpm with jet drive. I did switch from a MSD Pro Billett distributor to a HEI about 10 hours of run time ago.

    I double checked my clearance numbers and by the looks of the wear on the piece that broke off I was within 1/8" of bottoming out the connection.

    Did I do anything wrong?

    Obviously I have to pull the pan, find the other piece and check the bearings for wear.

    My next thought now is auto shut off for oil pressure loss, not sure what that involves since I use a GoPro on my gauges for data collection.
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    Some guy obnoxious001's Avatar
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    The normal HV77 does not include the drive shaft, unless you bought someone's package deal. The only way the shaft can be removed is from the bottom, first removing the oil pump. When you do that, you will want to take the pump apart and see if there is anything inside it, including any marks from something that may have passed through, but with a screen on the pickup, it's hard to imagine anything very big getting in there.

    If you have a slip collar distributor, I normally set by bottoming it into the drive with no gasket, and thus only have the thickness of the gasket for clearance. With a normal distributor, you don't have that option, but you will want to verify how much engagement you had, and even check your pump driveshaft length against a new one to make sure it was right. That's not a part that breaks very often in my many years of experience.

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    Member jetsonly's Avatar
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    Quote Originally Posted by obnoxious001 View Post
    The normal HV77 does not include the drive shaft, unless you bought someone's package deal. The only way the shaft can be removed is from the bottom, first removing the oil pump. When you do that, you will want to take the pump apart and see if there is anything inside it, including any marks from something that may have passed through, but with a screen on the pickup, it's hard to imagine anything very big getting in there.

    If you have a slip collar distributor, I normally set by bottoming it into the drive with no gasket, and thus only have the thickness of the gasket for clearance. With a normal distributor, you don't have that option, but you will want to verify how much engagement you had, and even check your pump driveshaft length against a new one to make sure it was right. That's not a part that breaks very often in my many years of experience.
    Thanks, that's what I was thinking, I've never heard this happening before. There's a 1/2" of slot on the distributor and I had 3/8" making contact, 1/8" from bottoming out. Will try and get the next one closer. Bought the kit from Jegs that came with the Mellings high strength shaft or so I thought.

    Any suggestions on next shaft? Canton racing? Sucks that such a low cost part broke. Could have been catastrophic, got lucky. Caught it within a few seconds.

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    Village Idiot fc-Pilot's Avatar
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    Barry speaks words of wisdom, and mentioned some good points. I have to say that I would probably not be using oil that thick. Then again that depends on a number of things but I build my engines to run 10-40 or 5-30 range of oil viscosity. Just another thought.

    Paul

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    Some guy obnoxious001's Avatar
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    Quote Originally Posted by fc-Pilot View Post
    Barry speaks words of wisdom, and mentioned some good points. I have to say that I would probably not be using oil that thick. Then again that depends on a number of things but I build my engines to run 10-40 or 5-30 range of oil viscosity. Just another thought.

    Paul
    Good point, without knowing oil clearances.

    I am an old school guy, run clearances that work well with straight 40wt or even straight 50wt on my forced induction engines.

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    Some guy obnoxious001's Avatar
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    Quote Originally Posted by jetsonly View Post
    Thanks, that's what I was thinking, I've never heard this happening before. There's a 1/2" of slot on the distributor and I had 3/8" making contact, 1/8" from bottoming out. Will try and get the next one closer. Bought the kit from Jegs that came with the Mellings high strength shaft or so I thought.

    Any suggestions on next shaft? Canton racing? Sucks that such a low cost part broke. Could have been catastrophic, got lucky. Caught it within a few seconds.
    Did you check the HEI when you replaced the MSD, or just assumed it was identical? I don't quite understand your measurement notes, I use a ruler or screwdriver inserted into the drive, measured to the distributor surface of the manifold, then compare to the distributor from the flange to the end of the shaft, which is short of the end of the gear.

    I don't believe that you need any special oil pump drive shaft, I have used various different brands without failures.

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    Member jetsonly's Avatar
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    No I didn't measure the 2 distributors. Didn't think I needed to, BBC Mark IV block. Should have.

    Yea measurement notes were not supposed to be in the pic. Used square slide ruler, fits in the hole and can move the slide square to get a accurate measurement. Bottom line I did have 3/4's of the slot engaged. Could get a little closer.

    7 3/4" was the distributor length from where it sits on the manifold to the bottom of the gear.
    7 11/16" was from the manifold to the bottom of the slot.
    The 1/4" & 3/4" were to measure the length of the slot inside the distributor gear and that it's 1/4" above the bottom of the gear.
    The visual makes the numbers work for me

    Engine built for 50w and has forced induction.

    Might be able to pull it apart next week. Curious to get the oil pump in my hands to check it out.

    Thanks again to both of you for your input

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by jetsonly View Post
    No I didn't measure the 2 distributors. Didn't think I needed to, BBC Mark IV block. Should have.

    Yea measurement notes were not supposed to be in the pic. Used square slide ruler, fits in the hole and can move the slide square to get a accurate measurement. Bottom line I did have 3/4's of the slot engaged. Could get a little closer.

    7 3/4" was the distributor length from where it sits on the manifold to the bottom of the gear.
    7 11/16" was from the manifold to the bottom of the slot.
    The 1/4" & 3/4" were to measure the length of the slot inside the distributor gear and that it's 1/4" above the bottom of the gear.
    The visual makes the numbers work for me

    Engine built for 50w and has forced induction.

    Might be able to pull it apart next week. Curious to get the oil pump in my hands to check it out.

    Thanks again to both of you for your input
    I am going to toss into this. I will ask one question--What bound up to cause the break in the drive-shaft.
    Last edited by ol guy; 10-18-2016 at 04:35 PM.

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    Quote Originally Posted by ol guy View Post
    I am going to toss into this. I will ask one question--What bound up to cause the break in the drive-shaft.
    Thinking that too. I can turn the shaft a little with a heavy wire bent sideways, but don't have a screw driver long enough to put pressure to see if it will turn all the way around. I heard the lifters starting to tick, saw the oil pressure just above zero and shut it down. I'll post what I find when I can work on it.

  12. #10
    Senior Member ol guy's Avatar
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    Quote Originally Posted by jetsonly View Post
    Thinking that too. I can turn the shaft a little with a heavy wire bent sideways, but don't have a screw driver long enough to put pressure to see if it will turn all the way around. I heard the lifters starting to tick, saw the oil pressure just above zero and shut it down. I'll post what I find when I can work on it.
    Good move on watching you're gauges. Until you find out what is in the pick-up I would put a hold on tearing the rest of the engine down. BUT!!!! You need to pull the engine out to get to the reason so It's a flip of the coin. I know if I had to pull the engine I would probably do a full inspect anyway. Gaskets are cheaper than hitting the water and sitting watching the boat float. Sure curious as to what you find. Best wishes. M

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    Senior Member Bubbletop409's Avatar
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    Years ago I had a similar incident in a BBC Howard day cruiser. Same sequence of events, my oil pump shaft was froze solid. Pulled engine, pan, oil pump, had to beat the gears out of the pump body. Culprit turned out to be a broken retainer ring from the top of one of my hydraulic lifters, found the other half in the pan. No thicker than a paper clip, thin enough to get past a standard pick up screen. Pump was junk.
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  14. #12
    Senior Member ol guy's Avatar
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    Quote Originally Posted by jetsonly View Post
    Thinking that too. I can turn the shaft a little with a heavy wire bent sideways, but don't have a screw driver long enough to put pressure to see if it will turn all the way around. I heard the lifters starting to tick, saw the oil pressure just above zero and shut it down. I'll post what I find when I can work on it.
    Until then I would treat it like a sore dick and not screw with it, Last thing you want to do is unlodge what caused the issue and wind out chasing your' tail. M

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    Quote Originally Posted by ol guy View Post
    Until then I would treat it like a sore dick and not screw with it, Last thing you want to do is unlodge what caused the issue and wind out chasing your' tail. M
    I agree with checking everything out before running it. I did find a piece of steel 1" wide 1/8" thick to get a bite on what's left of the shaft and it's definitely locked up, but can turn it back 1/4 turn then forward to where it hits something. Curious minds want to know, gonna have to wait a bit, busy at work. At the very least new oil pump & shaft + ...

    I have to figure I got lucky, water was to rough to hold the throttle open, plan was to go out the following morning in calm water. If it held till then I would have froze the motor on a long run

    Anybody use a oil pressure alarm or auto shut off? Thinking that will be a boat part high on the priority list now.

    Bubbletop - good point, in the past I had a motor that I found the top of hydraulic lifter coming loose and I snapped it back into place. Hope that didn't happen here, but something came apart.

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    I had that happen several years ago.
    As it turned out the sump had broke off the oil pickup tube and was coasting around in the bottom of the oil pan like a hockey puck.
    It might have been fine that way for a while but then it decided to suck up a small piece of the aluminum windage trey that had broke off and that seized the pump and broke the tab off the oil pump driveshaft. It shoved the distributor up out of the hole when it happened.

    I had just raced this local dude with a hydro and saw there was no oil pressure.
    Like you I caught it before any damage occurred.

    I raised the motor up out of the boat just enough to get the pan off, replaced the pump, and was back on the water the next weekend.

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