Water pump – ‘56 Firestone 30HP

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    jpatti75

    US Member - 2 Years
    Replies: 291
    Topics: 43
    #227487

    Hi all ,

    I’m slowly building a Firestone 30HP motor from two parts motors. I tested the water pump over the weekend to ensure it is doing its job, since it is one of the dreaded high-mounted water pumps that doesn’t prime easily (but not a bail-o-matic pump like on the Scott-Atwater badged motors). While it is pumping, what I can’t figure out is why in the wide-world of sports it has four holes in the water pump cover that release water. I have a picture below of the pump cover so you can see the holes and the link to a video below shows water slopping out when I run the pump with the drill. It still pumps water, but the resultant loss in water pressure due to the holes confuses me. What I am hoping someone can tell me is this is perfectly normal and to stop being a knucklehead and move on.

    Thanks,
    JP

    Firestone 30HP Water Pump

    Water pump test video

    • This topic was modified 3 months, 1 week ago by Avatarjpatti75.
    • This topic was modified 3 months, 1 week ago by Avatarjpatti75.
    Mumbles
    Mumbles

    Canada Member - 2 Years
    Replies: 4850
    Topics: 268
    #227491

    Maybe to quench the fire coming out of the motor and to help keep the exhaust housing cool?

    frankr
    frankr

    US Member - 1 Year
    Replies: 5622
    Topics: 49
    #227495

    After pondering about it awhile, I wonder—-is it to create a water seal to prevent exhaust gasses from entering the pump via the hole the drive shaft passes through(??)

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    jpatti75

    US Member - 2 Years
    Replies: 291
    Topics: 43
    #227501

    Thanks for the replies, gents. I think both of your theories have merit, especially given how close the water pump is to the powerhead. That said, the bailer-style pumps on the 33HP Scott-Atwater motors (with the bailer chamber stacked on top of the main impeller chamber) have a solid cover … i.e. no holes. So, if the water is meant to provide either cooling to the exhaust or keep the pump housing cool (being so close to the powerhead), I would have expected cover holes on the bailer-style pumps as well. As for the exhaust gases, maybe the double-stacked impellers on the bailer provide enough of a seal that the cover holes aren’t necessary on those, but needed on the single impeller pumps like mine?

    Spanky

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    billw

    US Member - 2 Years
    Replies: 1451
    Topics: 44
    #227515

    It’s almost unbelievable that the pump will pull a vacuum with those four holes. I could see it working if the holes were on the pressure side of the housing; but with the even spacing, it seems like at least one of the holes would be on the vacuum side. I don’t do much with Scott Atwater but I do a LOT of Mercury automatic transmission stuff; so nobody gets the importance of pump vacuum more than me. Man, I certainly don’t get it!

    Long live American manufacturing!

    frankr
    frankr

    US Member - 1 Year
    Replies: 5622
    Topics: 49
    #227521

    What the OP didn’t mention is that there is a stainless plate under the cover plate. As I recall, there is only one bleed hole in the stainless plate, not four. Also, the double stacked bailer pumps DO have a bleed hole to pass water from one section to the other. That is necessary to keep the bailer impeller wet. Whether or not it also keeps exhaust out of the pump is a good question.

    frankr
    frankr

    US Member - 1 Year
    Replies: 5622
    Topics: 49
    #227523

    The 30-33hp Bail-A-Matic pump, showing the bleed hole almost hidden by the o-ring. Note that it is on the pressure side of the main pump.

    33hp-bailer-pump-photoshopped

    • This reply was modified 3 months, 1 week ago by frankrfrankr.
    • This reply was modified 3 months, 1 week ago by frankrfrankr.
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    jpatti75

    US Member - 2 Years
    Replies: 291
    Topics: 43
    #227526

    Thanks for explaining that, Frank. Here is the Firestone pump diagram. Both type pumps use the same SS plate.

    Firestone pump diagram

    • This reply was modified 3 months, 1 week ago by Avatarjpatti75.
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    jpatti75

    US Member - 2 Years
    Replies: 291
    Topics: 43
    #229342

    After weeks of researching this issue since posting, Doug Penn pointed me to a member in Texas who has an extensive Scott-Atwater collection. He stated my water pump is just as it should be from the factory, and the water that is expelled from the pump is to cool the pump housing since it is mounted so close to the powerhead. (Mumbles, I think you called it!) With that, I felt good about installing the powerhead. To paraphrase one of my uncles, they should have slapped the mama of the guy who came up with that spring suspension system for the powerhead! 😉

    She ain’t pretty, but here she is in the assembly process…

    Firestone assembly 1

    Thanks for all the help, gents!
    JP

    Buccaneer
    Buccaneer

    US Member - 1 Year
    Replies: 4536
    Topics: 777
    #229346

    I just re-worked two water pumps on Scott 7.5 hp Bail-a-matics,
    using Honda impellers and modifying the liner. I defeated the
    bailer pump on both units.
    Both pumps expel some water around the top of the pump
    where the driveshaft goes through, but otherwise seem to pump
    water well…….. at least in my test bucket.

    Perhaps I’ll worry about the leakage less thinking about your 16 hp with
    the water cooled exhaust.

    My 7.5’s have a baffle plate that slides in the grooves in the middle
    of the housing to separate the exhaust from the pump somewhat.
    Does the 16 hp not have that?
    Groove shown in my photo, but the baffle plate is not installed yet.

    DSCN0329

    Prepare to be boarded!

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    jpatti75

    US Member - 2 Years
    Replies: 291
    Topics: 43
    #229351

    Bucc,

    I know a couple guys doing tests with those Honda impellers that are reporting good results, too. Well done!

    I’m not sure about the 16HP models … mine is the less abundant 30 HP model, and it does not have the baffle plate. There is, however, a big rubber gasket/grommet at the base of the crankshaft to seal off where the crankshaft mates with the driveshaft. They must have wanted provide the crankshafts/driveshaft a little extra protection from water since the water pump is spewing water from the four holes in the cover so close by.

    JP

    frankr
    frankr

    US Member - 1 Year
    Replies: 5622
    Topics: 49
    #229353

    I sort of remember a service bulletin concerning that boot to protect the splines.

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    jpatti75

    US Member - 2 Years
    Replies: 291
    Topics: 43
    #229371

    It’s a fairly substantial boot, protruding about 1.5” from the base of the powerhead. Seems to have done its job for the last 65 years, as the splines are still in great shape. I still slathered everything with a generous amount of grease prior to assembly.

    Buccaneer
    Buccaneer

    US Member - 1 Year
    Replies: 4536
    Topics: 777
    #229372

    One of my 7.5’s splines are good, the other “so – so”, so thanks for the reminder
    about water intrusion to the splines.
    The “grab handle” assembly plate covers the top of the LU housing, and
    has a cork gasket affair where the driveshaft goes through. I’ll have to
    make sure that’s in good order.

    Prepare to be boarded!

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