Thread: overheated motor- think I blew out water pump rear seal

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Good advice from Roger.
What usually happens is that the bearing goes south, allowing the impeller shaft to wobble and wipe out the seal and you'll begin seein' puddles of water on the ground. Most often, the bearing is wiped out because its effective service life is over, but sometimes the bearing is wiped out due to excessive tension on the pump drive belt, so pay attention to that when you get her back runnin'.

I'd at least do a compression test on her. Here's the procedure....
Get yourself a good screw-in compression tester, as opposed to one with a rubber tip that you hold into the spark plug hole.
Warm the motor to operating temperature.
Remove the air cleaner.
Use wire or string to tie the primary throttle blades wide open so the motor can breathe.
Disable the coil by removing the hot wire from it to prevent a fire.
Remove all spark plugs to make it easy for the starter motor to turn the crank.
Turn each cylinder through at least 5 compression cycles (chuffs) to insure max gauge reading.
Write down the cylinder number and the reading for each cylinder.

A good running low-compression ratio motor with stock or slightly hotter cam and good ring and valve seal will generally show ~140-150 psi on each cylinder. 165 psi is the generally accepted limit for using pump gas, however with a good, tight squish of 0.035" to 0.045" and a state of the art heart-shaped combustion chamber with no sharp edges anywhere, I have seen motors operated on pump gas with compression tested in excess of 200 psi.

One other thought, if any water or anti-freeze solution has gotten into any of the cylinders, the spark plug for those cylinders will look like brand new because they will have been steam-cleaned.

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