I tried test running this motor several times in the barrel, and it
would quit pumping water after 1 -2 minutes. Shut it off, restart it,
and it would pump great again for about the same amount of time.
The first time or two I was thinking the pump intake screen plugged up,
as the water looked pretty questionable.
Drained and scrubbed out the test tank, fresh water, and it still did the
same thing.

Today I took the prop off, and I ran it for twenty minutes with no pumping
issues. Just the exhaust alone blowing near the prop area seems to cause
plenty of agitation in the barrel.
Hopefully I won’t have any issues once it’s on the boat.

I’ve never had problems running a 4 hp in the barrel before.
The prop is 8-1/2″ diameter. Not sure if this Viking would have had
a brass prop in 1936, nor am I sure it’s a correct replacement if not.
There’s the number “2” stamped on the prop in three places, and a “1”
stamped as well…… not sure what to think about that.

Any Viking service bulletins “out there” talking about cavitation issues
in 1936? 🙂

VIDEO ……….
https://youtu.be/wG4ZBLc5-6s