Water pump – ‘56 Firestone 30HP

[jpatti75]

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

Water pump test video

• This topic was modified 3 years, 3 months ago by jpatti75.
• This topic was modified 3 years, 3 months ago by jpatti75.

[Mumbles]

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

[frankr]

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(??)

[jpatti75]

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?

[billw]

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]

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]

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.

• This reply was modified 3 years, 3 months ago by frankr.
• This reply was modified 3 years, 3 months ago by frankr.

[jpatti75]

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

• This reply was modified 3 years, 3 months ago by jpatti75.

[jpatti75]

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…

Thanks for all the help, gents!
JP

[Buccaneer]

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.

Prepare to be boarded!

[Author]

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