Raw Water Pump Leak - 5.7 engine

[gilbertnautique]

I just replaced the impeller and hooked up the hose to the Perko Flush Pro to test and found water leaking out near the pulley.

It looks like it is leaking out of the shaft seal on the housing?

I have the hose barely on to fire up and then turn the hose up to run as directed by flush pro.

It still spits out water when running but not like when it is not running.

Could hose pressure be causing this to leak?

The red arrow shows where it is coming back from the pulley.

Thanks

[jpwhit]

Yes, the input side of the raw water pump is not designed to be under pressure. It doesn't matter if hose is barely on, without water flowing the pressure will be whatever the water pressure of your house is. That’s typically between 50 and 70psi which is way more pressure than a boat cooling system would ever normally see. That’s why a fake-a-lake is designed so water will spray out the sides. I would probably put a Y somewhere on the hose and crack one of the fittings open to have a constaint spray of water. Then once the boat is started, turn the water up enough that you still have some water flowing out of the Y.

But there shouldn't be any water coming out when it's running. If it's only a drip, then you may not need to fix it immediately, but you also don't want water getting into your pump bearings and ruining the pump.

[jmo]

When you replaced the impeller, did you also replace the main o-ring on the housing and the o-rings on the back of the 3 bolts? If not I bet it’s one of the bolt o-rings.

[Machspires]

Like jmo said...

Had a small leak from the same area last year during the first engine run of spring. Incorrectly seated O-ring was the culprit...as well as my re-installation buffoonery. Put in a new O-ring with silicone plumbers grease and all was good.

Ditto on not running water with engine off. I use a hose shut off valve at the end of my hose, I start the engine, then slowly open the valve (which is only ~10 ft away from the helm) until it fills up the clear portion of the perko flush.

[gilbertnautique]

Thanks. I did replace the O-ring and screw O-rings, but did not grease them. I'll replace them again and go from there.