Fresh water impeller

[SPembleton]

I am replacing my freshwater impeller for the first time (I just bought the boat). The PO left a number of impellers. The old one is held on with a snap ring, but the new ones he left don't use a snap ring. Is this just a different style? Can I use the new ones?  Also, the shaft came out when I tried to pull out the old impeller. It goes back in easily, but should I grease it before I put it back?

[Clay Greene]

Not sure what you mean by the statements that the new impellers "don't use" a snap ring.  You re-use the old snap ring with the new impeller.  Is there not a space on the impeller face in which the snap ring would insert?  I believe some have said that you don't need the snap ring at all because there is no place for the impeller to move because of the cover. 

I don't think there is any reason to lubricate the pump shaft before re-inserting.  There is oil on the engine side of the pump housing and it is water lubricated on the impeller side. 

[SPembleton]

Yes, what I mean is that there is no room for the snap ring.  The old impeller was cut back near the shaft to allow room for the ring. The new impeller is flush all across the top and therefore the grove for the ring is not exposed

[Ron Hill]

Steve : I assume that you are talking about the raw water engine impeller for engine cooling??  

If you are and you have an Oberdoffer pump there is no need for the snap ring.  Once on the shaft the faceplate will hold it in place - it can't go anywhere!!  

A thought

[sailaway]

I always lubricate the new impeller with a thin film of Vaseline so the first 10 rpm there is some lubricant till the water  gets there. Also it helps with suction. My impellers last 3 seasons fresh water. Charlie

[Ron Hill]

Steve : I always used liquid detergent to lube the raw water impeller. 
That way no "greasy" product residual could get into the hoses or the heat exchanger!

A thought

[KWKloeber]

Steve : I always used liquid detergent to lube the raw water impeller. 
That way no "greasy" product residual could get into the hoses or the heat exchanger!

A thought

Shouldn't use petroleum based -- another alternative is PTFE-based SuperLube, a tube of which no boat should be without!

Presume you may have an aftermarket impeller -- the Ob impellers have the indent for the clip, which Ron is correct about -- can be trashed once the pump is out of the Ob box (it ONLY keeps the shaft in the pump during storage/shipping.)  If so, be careful - they might not meet the tight tolerance needed for proper suction.

There's no harm in running some SuperLube on the pump shaft, tho it's not going to last long.
Do you have a grease cup on the pump?


Ken

[SPembleton]

Stu: Yes, I meant RAW watt pump, and Ken: no grease cup.

As always, thanks all.  Having this site as a newbie is invaluable!!