Yanmar 1gm10 with PSS seal - major leak

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Ammonite

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Was helping out a mate to track down a leak on his Fantasia 27 today and it didn't take long to work out that when the engine is in gear it's leaping around so much that there is a steady stream of water leaking from the PSS seal. I reckon the shaft is moving side to side by about 10mm so no major surprise that it leaks. The engine is a 1gm10 and the mounts were supposedly changed a year ago although one of the rears is now split. The seal and shaft was also replaced last year.

I'm just looking for a few pointers as having a beta 20 I'm not used to engines that leap about! The engine mount clearly needs replacing but the good ones are so soft I can't see this stopping the leak.
 
Chaktoura said:
Was helping out a mate to track down a leak on his Fantasia 27 today and it didn't take long to work out that when the engine is in gear it's leaping around so much that there is a steady stream of water leaking from the PSS seal. I reckon the shaft is moving side to side by about 10mm so no major surprise that it leaks. The engine is a 1gm10 and the mounts were supposedly changed a year ago although one of the rears is now split. The seal and shaft was also replaced last year.

I'm just looking for a few pointers as having a beta 20 I'm not used to engines that leap about! The engine mount clearly needs replacing but the good ones are so soft I can't see this stopping the leak.
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Were the mounts correctly specified? If it's leaping about, presumably not.
 
TQA said:
Check to see if the airbleed pipe to the seal has hardened. Mine had and replacing it helped.

Increase the preload on the seal slightly. 3 mm made a difference for me.

How old is the bellows? 7 years and they need replaced.
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The OP said that "The seal and shaft was also replaced last year."
 
Chaktoura said:
What seal would you suggest?
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It will be better with a radial seal rather than a face seal if the engine has a solid coupling to the shaft, so a stuffing box on a flexible hose or a Tides Marine seal would work. Have you tried resetting the pressure on the PSS according to the instructions as if the bellows is not properly loaded there is not enough pressure to keep the two faces in contact.

Although the 1GM does bounce around a bit at tickover it should smooth out as soon as there is some revs. Important that you set the mounts correctly and check the lock nuts regularly as they have a habit of slacking off which apart from allowing more movement may cause delamination of the mounts.
 
Yanmars have very soft mounts and tend to writhe around on idle - I've had the PSS seal on 2GM and 3YM and never had any problem.

Yanmars have "soft mounts" ie the thrusr from the propeller is transmitted to the hull via the engine mounts.

Either the bellows on the PSS seal has been set too slack or (more probably) there has been a rope around the prop, exerting sufficient force to split the mounting or bend the shaft - or pull the shaft slightly out of the clamp.
If the mounting has broken and none of those things has happened the mounting was faulty and not fit for purpose.
Despite the remarks by technophobes, it would be a definite regressive step to go back to a dripping, high-friction stuffing box.
 
TQA said:
Fix the mounts first of all.

Check to see if the airbleed pipe to the seal has hardened. Mine had and replacing it helped.

Increase the preload on the seal slightly. 3 mm made a difference for me.

How old is the bellows? 7 years and they need replaced.
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The recommendation is that they're replaced - mine was entirely unmarked and as good as new when it was changed in year 9.
 
Tranona said:
It will be better with a radial seal rather than a face seal if the engine has a solid coupling to the shaft, so a stuffing box on a flexible hose or a Tides Marine seal would work. Have you tried resetting the pressure on the PSS according to the instructions as if the bellows is not properly loaded there is not enough pressure to keep the two faces in contact.

Although the 1GM does bounce around a bit at tickover it should smooth out as soon as there is some revs. Important that you set the mounts correctly and check the lock nuts regularly as they have a habit of slacking off which apart from allowing more movement may cause delamination of the mounts.
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Apologies - it is a tides marine seal not a pss. I should have checked rather than assumed. The engine has a solid coupling and there is a steady stream of water from the front of the seal at low revs but it also leaks higher up the rev range at about a litre per hour apparently. The previous owner has even fitted a small bilge pump to deal with the problem so it's not a new issue. Replacing the failed mount is going to be expensive and there has to be a reason why its failed so soon. The seal has always leaked as well so while new mounts may improve things I cant see it resolving them completely. The seal, mount and shaft replacement was undertaken professionally at vast expense.

Is it worth replacing the yanmar mounts with a stiffer variety and living with the increased vibration at idle?
 
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Chaktoura said:
Apologies - it is a tides marine seal not a pss. I should have checked rather than assumed. The engine has a solid coupling and there is a steady stream of water from the front of the seal at low revs but it also leaks higher up the rev range at about a litre per hour apparently. The previous owner has even fitted a small bilge pump to deal with the problem so it's not a new issue. Replacing the failed mount is going to be expensive and there has to be a reason why its failed so soon. The seal has always leaked as well so while new mounts may improve things I cant see it resolving them completely. The seal, mount and shaft replacement was undertaken professionally at vast expense.

Is it worth replacing the yanmar mounts with a stiffer variety and living with the increased vibration at idle?
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If done by a 'pro' and within 12 months I would start by having a word with them. what you describe should not be happening....
 
RivalRedwing said:
I
If done by a 'pro' and within 12 months I would start by having a word with them. what you describe should not be happening....
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Turns out my mate wrapped the prop after the work was done so suspect this was the cause of the failed mount. I'm going to give him a hand to check the shaft hasn't been bent and go from there. Would be interested to hear from anyone would has used mounts from someone like R&D or AV Industrial. The seal has leaked from new even with new mounts and a new shaft so sticking with the OEM mounts isn't going to resolve the leak on its own
 
all the mounts need to be those recommended.
i rengined my 26 footer with a 2nd hand volvo & used some yanmar mounts i got new for a good price. it ran a smooth as silk ashore,upon launching the whole deck head vibrated up & down. i then bought at some expense volvo mounts, all was sweet again, the volvo mounts were much softer
 
I have a 1GM10 and a PSS on Snark. Due to the shaft walking up inside the shaft coupling over a season, I have to relocate it during the winter refit and re-set the PSS clearance. I have done everything I can think of short of drilling the coupling and inserting a pin to stop this without effect. Even torquing up the coupling bolts by 20% and screwing a SS terry clip around the shaft. At tick over there's a drip from the seal, but this stops when the revs rise. I usually have to tighten up the seal twice during a season.

Don't forget that Yanmar have different specs for the forward and after mountings. Make sure they're the right way round.

Also the rubber doesn't like diesel dripping on it so I have a plastic shield over the fwd mounts, in car of a leak or for when I bleed the fuel lines.
 
Chaktoura said:
Turns out my mate wrapped the prop after the work was done so suspect this was the cause of the failed mount. I'm going to give him a hand to check the shaft hasn't been bent and go from there. Would be interested to hear from anyone would has used mounts from someone like R&D or AV Industrial. The seal has leaked from new even with new mounts and a new shaft so sticking with the OEM mounts isn't going to resolve the leak on its own
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Sounds like the seal is defective. It should not leak at all, even if the engine/shaft moves around as the two lip seals move with the shaft. Check that the seal is the correct size and not a 1" running on a 25mm shaft. As suggested given the age the first step is to get the installer back to sort it out.

For mounts you might consider Poly Flex from www.southerncrossmarine.co.uk Have heard good things about them, but last time I looked they were even more expensive than Yanmar.
 
ghostlymoron said:
That's the problem with high tech modern seals. If they fail, it can be significant unlike a packed gland which can just be tightened down.
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agree, i repacked mine & replaced the hose 12 yrs ago when i fitted a new engine & shaft, no leaks no grease spewing out doesnt get hot. i can turn the shaft by hand on a cold morning so the gland isnt over over tight
 
sailorman said:
agree, i repacked mine & replaced the hose 12 yrs ago when i fitted a new engine & shaft, no leaks no grease spewing out doesnt get hot. i can turn the shaft by hand on a cold morning so the gland isnt over over tight
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I thought about going high tech when I bought my boat, but was talked out of it, I'm glad to say. A stuffing gland works fine for me and as ghortlymoron says, failure with them tends to be progressive.
 
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