leaking prop shaft seal

westernman

westernman

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My prop shaft seal does not leak when I am not using the engine, but leaks a lot when I do.

Am I risking anything in using the engine before I can get it seen to?

E.g.

1) sinking rapidly
2) damaging something

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Do you know what seal you have?
Volvo?
Tides Marine?
Deep Sea Seal?

Could be that engine is wobbling on soft mounts,, or just leaking through lack of lubrication on rotation.

My Volvo seal leaked as my engine was out of alignment. Its quite a tight tolerance. That didnt leak stood still either.

I would say its a low probabilitty of total failure, unles you intend motoring hundreds of miles at a go.
 
As full circle sais what type is it?
If it is one with stuffing, water dripping when turning is good for the packing as it lubricates and cools, too much dripping it needs tightening or packing replacing.
 
Sorry, but I do not know what type it is.

It has a kind of corrugated rubber covering outside and when you squeeze it water spurts out.

When motoring it is leaking several gallons per hour.

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It sounds like a Volvo/PSS or similar, in which case it should not leak at all. I would get someone to look at it asap. That sounds a fair rate of leak.

Ours did that - at first only when it was rough and we were motoring, then after a few days, all the time. We had to replace it, which can only be done out of the water, of course.
 
If the water is coming out between the two faces then it could be because it is not set up properly. The seal is two rotating faces pressed together by the rubber hoses. This type of seal can fail completely with obvious consequences. Best get it seen to or better replaced ASAP.
 
Does it have tubes leading to it and from it to an oil reservoir ? If so it could be a Halyard, but it does sound more like a Volvo.
 
If it is the PSS type seal then check that the steel rotor is correctly compressed against the carbon sealing ring. It has been known for the grub scews that secure the rotor to work loose and the rotor to move away down the shaft.
 
No great problem, your descriptions sound like a well worn Volvo seal. If you can put up with pumping bilges should not be a problem, but make sure the shaft is not throwing leaking water over any electrics.


I changed mine when leak under motor got too bad for my comfort after 21 years. Found the old lip seals well worn compared with replacement which was not a great surprise.

Exprimented with a normal hose clip before I changed the seal to gently nip and squeeze the in the rubber seal with the hose clip to reduce leak to regular drip under motor so this would be a get you home dodge. You would need some engineering 'feel' to do this with confidence I would advise.

You need to lift out to change the seal. This is not a complicated job but you need normally need to pull the shaft / gearbox coupling off which often the most fiddlesome part of the job. If the old seal has worn grooves in the shaft the proper way is either to sleeve the shaft or get a new one. However I adjust the position of the seal by a couple of millimeters so the new seal lips bear on slightly different unworn part of the shaft.

Good luck


Brian
 
Most unlikely to be a Volvo from the description - Corrugated hose sounds like PSS if it is a face seal or possibly a Tides if it has lip seals.
 
Just be sure it isn t just a matter of adjustment before you spend lots of squids. It is not unknow for these seals to require resetting due to either the bellows relaxing a little with age or the seal carrier on the shaft moving towards the engine.

In the event of either of these events then see what happens if with the engine stopped you move the carrier till it is just touching the bellows seal when at rest then slide a further 5/8 mm aft to compress the bellows and secure.

Run the engine and see if the leak has stopped. Check the seal after running under power to ensure it remains cool.

I suspect some of our less reputable spanner men will happily relieve you of funds to replace the seal when only an adjustment is necessary.

On some seals the shaft seal face is adjusted by loosening a jubilee clip where the rubber carrier is fastened to the shaft and adjusted in a similar manner before resecuring the jubilee clip.

If the compression is insufficient then the seal leaks due to the engine moving forwards on its elastic mounts when under load. If this is the case the seal may stop leaking when going astern.
 
Thanks for the clear explanations. I now understand what I am looking at and what to look for. So next time I am on the boat I will do exactly what you suggested.

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