Impeller minutia...

[jstaff]

From an older thread:

I have 3 pumps that I'm overhauling and I noticed, that when removing the old impellers, the side with the little dimple has always been facing the back cover.

So I've been installing the new ones the same way.

I changed my impeller on the boat last year and that one would only go on one way, dimples were facing out.

Is this just a coincidence or does it matter?

Food for thought
Rick

I've been wondering if the molded protrusions, or bumps are intended to provide "lubrication" (water) between the impeller and one of the pumps surfaces. But which one?



I have seen impellers installed in both directions but I would think that the engine side of the pump would benefit more from the additional lubrication provided by the small protrusions.

[Al Schober]

I don't think it matters.
I think those bumps are just residuals from the molding, and whether they're against the cover plate or the inner wall won't make any difference. Both those surfaces tend to wear. When the cover plate is shot, a new one is cheap. When the inner wall is gone it means a new pump. Hey, stuff wears out. Fortunately, my knees haven't given out yet (in spite of years of competative bike riding).
Noticed the Mystic Seaport Antique Boat Show this year is for boats prior to 1970. Wonder if this means my Tartan 30 (1973) will qualify in 3 years??