Dented Impeller Plates

[chris-p]

We have all gone to do a water pump, and found the impeller plate with a "dent/buldge" in the middle of it. We flatten them back, and carry on. I especially see this on the Big Twin 40hp motors. What is the science here, water pressure? Must take a heck of a lot of force to dent one of those ss plates. I would think more than the impeller can make, but who knows

[sydinnj]

maybe they do not drain totally and slightly freeze. I just did a 35 evinrude that was this way.

[chris-p]

Good thought. Ice is pretty powerful, hard to think that inside the impeller housing would not drain, but perhaps thanks.

[RICHARD A. WHITE]

The drive shaft can move up and down some right??? might be enough…

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[frankr]

Just how much bulge are we talking about? We know they aren’t totally flat, right?

[chris-p]

Yeah, no im talking about weird tumours in random places in middle of plate.

Perhaps it is ice damage, you guys down south probably have never seen it then!

[frankr]

quote Chris_P:

Yeah, no im talking about weird tumours in random places in middle of plate.

Perhaps it is ice damage, you guys down south probably have never seen it then!

Wanna bet? We see that stuff you guys haul down here. But that’s ok, bring more. Ours are all destroyed by salt water.

[PugetSoundBoater]

I always check the lower unit drain holes and water passages when doing a water pump, to prevent freeze damage and to allow salt water to drain well

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[dan-in-tn]

Kinda passed over that part about beating them out flat again. Frank asked if everyone knows they aren’t suppose to be flat? They are suppose to have a crown at the middle to help the hub seal the driveshaft so the pump will prime and pump better. If you look at a new OEM plate vs a Sierra plate you will see a difference. Just looking at one today.

Dan in TN

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