How do drip less seals work

A

ALKA2710

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This is my first boat that does not have out drives. Can anyone explain how the dripless seals work. Also what is involved in changing them. Looks like a real knuckle scraping job. Thanks Al
 
https://www.youtube.com/watch?v=3UvyF-NRooQ It has water tube coming from motor and a tube out.
Should never see any water at all.
The O Rings and bellows keeps the water out.

If your lucky some have a spare seal on them.
 
There is also the Norscot dripless seal http://www.norscotshaftseal.com/ that does not use raw water to cool the seal, but uses hydraulic fluid instead. I installed these about a year and a half ago and really like them. Not a drop of water out of them and no appreciable fluid loss in a years time.
 
There are a number of different seal types. Lip seals are rubber etc. and spring re-enforced that looks like a wheel bearing seal. They wear out and leak and that is why they have spares installed on the shaft so you can slide a new one in while in water. Packing glands are not dripless and have their draw backs.
Then there are the others that seem to wear better. We switched to Lasdrop Gen 2 from Tide Marine.
 
I also have the Norscot Seals. I did a change two years ago due to the outer hose delaminating and leaking so I redid the seals at that time as well as replacing the shaft log hose. No appreciable hydraulic fluid loss in two years running and we run the engine about 150 hours per season.
 
Two basic types of seals:

The lip seal -- which is essentially rubber compressed around the shaft by a spring. Cheap, but subject to wear out quickly.

The mechanical face seal -- This is the PSS type. It basically seals via two ultra smooth faces of carbon or silicon, etc. One is a stationary face which attaches via a bellows to the shaft log. The other is the rotary face which attaches to the shaft. The bellows/spring keep pressure on the faces to provide the seal. They need water for cooling and should last a long time.
 
Anyone know when cooling water become required for PSS seals? My 1987 vintage aren't water cooled. And, I've only had to replace the rubber boots once since. So they do last a long time. Great customer service from them, too.
 
quote:
Originally posted by damaib

There is also the Norscot dripless seal http://www.norscotshaftseal.com/ that does not use raw water to cool the seal, but uses hydraulic fluid instead. I installed these about a year and a half ago and really like them. Not a drop of water out of them and no appreciable fluid loss in a years time.

Click to expand...


I have Norscot as well the only fluid I have lost was from a leak in the canister I have owned the boat for 7 years and they hold real well! I like the idea of not having additional water lines to fail and cause a major leak!
 
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