Water pump seals and gaskets / oil leak

[tenders]

I just replaced the shaft, seals, and gaskets of my MMI water pump purchased a few years ago. It had received inadequate lubrication, as evidenced by leaking water, which led to discovery of a scored shaft, and replacement of the shaft, and installation of the Moyer Grease Pump system.

Upon launch I discovered that a fair amount of engine oil is leaking out around the engine side of the pump. It amounts to several drops a minute, and it will nearly saturate a paper towel in 30 minutes of running. This is the first mention I've seen of oil leaking out around the pump.

The pump was attached with the proper gasket and black RTV sealant.

The oil appears to be coming from the weep hole, so I believe it's actually the brass seal that's leaking.

What's the right procedure to install those seals? Based on something I had written down in my notes several years ago, I put them in so the letters cast into the seals are facing each other (i.e., the non-lettered side is up against the impeller side of the pump, the other non-lettered side is up against the engine side of the pump) and tapped them in with a small hammer.

Perhaps I deformed the seal with the hammer, or didn't tap it in far enough? How far should it go, and should I put any kind of sealant ahead of or behind the seal? Seems like that might contaminate the engine oil.

This along with the Moyer value-add pages on pump maintenance, would be a good sticky item in this section.

Thanks,
tenders
1969 Ericson 32 #112
Muxie Duxer
A4, V-drive
HYC, City Island, NY

[Don Moyer]

Tenders,

I'm attaching a Q & A that we prepared a short while ago for changing Oberdorfer shaft seals. You actually installed yours correctly. I don't have a good explanation of why your new oil seal would be leaking.

As you probably realize, the seals are identical, they simply function in two different purposes; one to keep the water in the impeller chamber and the other to keep oil from leaking out from the engine on the flange side of the pump. I'm wondering if in scouring the shaft from lack of lubrication, the housing of your pump is enlarged to the point that the new shaft is too loose (wobbly) in the housing. It's a little difficult to tell you how much is too much play, but we would be suspect of any shaft to housing clearance of over .005".

We should probably include this Q & A in with each order for new seals.

Don

[tenders]

Thanks for the response, Don, and for the very helpful Q&A. I also discovered there's quite a lot of content in the forum if you change the default user setting to look back at "all posts" rather than just the last 30 days' worth!

I happened to have the old pump body on hand so I carefully installed a new set of seals and the virtually new shaft/impeller from the pump that was allowing the oil to leak by. (Oh, and the Moyer speed-seal plate with the thumbscrews. And the Moyer grease-gun connection in place of the grease cup. And the Moyer water pump bolt extender....)

No leaks this time. This doesn't actually prove anything about the cause of the leak, though, since it was a different pump, and one which had been replaced because I knew it needed new seals and I wanted a spare.

Your theory on the shaft scoring causing degradation of the shaft "alley" and therefore wobble and oil leaking is certainly plausible. We won't know for sure until the current installation wears out, which with the grease gun setup I hope will be never, but I have two working hypotheses which are simpler, and which justify my keeping the other pump around as a spare.

They are:
(1) (low likelihood) defective oil-side seal, or
(2) (higher likelihood) misaligned oil-side seal. Using a hex socket and a hammer I had tapped in the oil-side seal so that it was not flush with the pump flange but slightly countersunk, perhaps 1/16". It looked OK, but if this were not perfectly parallel with the shaft it's easy to imagine that the integrity of the seal could have been compromised. This is not a problem with the water-side seal because it seats up against the pump body when properly installed.

My key takeaway: even despite the convenience of living within 1 day of UPS ground delivery from Moyer Marine's sprawling Pennsylvania warehouse, it's very helpful to have an extra pump and a few replacement parts (seals, gaskets, shaft, impeller) lying around. We only lost 20 minutes of sailing time on this.

Thanks again Don.

1969 Ericson 32 #112
A4, V-drive
Harlem YC, City Island, NY