Rubber Cap on Impeller

[j.robinson389]

Still learning my way around my boat, and I have question about the impeller. When we bought the boat, the first thing we did was change the impeller, when we pulled it out it had a rubber disc/button/plug in the end of it. The replacement impeller we ordered looked identical except it didn't have the rubber piece with it. Is this piece needed what is it for? We have changed impeller twice since then and always pulled the rubber disc from the old impeller and put it on the new one. I wish I had taken pictures now, but a generic picture will have to do.

The disc sits where the yellow ring is and basically creates a flush surface on the end of the impeller.

[DWhynot]

Not needed, and I've never seen one...

[JasonK]

If it's a Mercruiser like mine: I always re-use mine too. Why wouldn't we? Go ahead and test it out without one.

That 97 Vette engine has a different pump setup along with all the Indmars.

Edited July 17, 2013 by JasonK

[DWhynot]

If it's a Mercruiser like mine: I always re-use mine too. Why wouldn't we? Go ahead and test it out without one.

That 97 Vette engine has a different pump setup along with all the Indmars.

Ohhh, a Mercruiser... My Bad.

[JasonK]

DW just be glad you don't have our pump setup. It sucks... lol

[j.robinson389]

DW just be glad you don't have our pump setup. It sucks... lol

Yes, the Mercs are more difficult, but when doing the swap in the driveway I just pull the four bolts from the belt pulley and do the entire swap on the bench in the garage. One thing nice about the 3-piece pump is that you can push the impeller out of the hole rather than having to pull it. On the other hand, I worry every time about cracking the plastic case when tightening the bolts back up.

[scfdfireman]

It may help seal the small area between the shaft and the spline of the impeller. Any reduction of vacuum loss will help overall performance of the impeller...