Leaking Volvo Shaft Seal?

[Skylark]

I suspect that I have a leaking shaft seal. Any views and advice would be much appreciated.

The boat is a Beneteau 36 ft with Volvo MD 2030. She is 2001 with about 600 hours. I don't think that the seal has ever been changed despite the Volvo 5 yr / 500 hour recommendation. It's been greased and vented for the last two seasons that I've owned her.

The boat has spent most of this season in the marina, I've hardly used her. (Perhaps lack of use may contribute to the problem?) I recently notice sea water in the bilge. I dried her out and she collected almost nothing in a week tied alongside. Yesterday, I motored 6 hours and she collected 1 to 2 litres. She was lifted out for winter.

It certainly looks to be coming from this area. The seal area through hull cavity is wet and there is sea water around the engine bearers making its way towards the bilge.

There are a couple of nearby skin fittings but they look secure.

I have not yet checked the engine sea water cooling circuit for leaks. Not sure if this is a vulnerable area, given her age?

If it is the seal, how big a job is it to replace. Any pitfalls. Is it DIY or should I simply sign over my salary to the yard?

Comments most welcome. Many thanks.

 

[SimonD]

This type of seal tends to fail gradually as the rubber hardens. However, they tend to last onger than the 500 houyr recommendation - some on the forum have reported years of use.

Not a big job to replace - I had an engineer do mine just because I couldn't undo the allen screws clamping the shaft to the flange. I think the seal is £80 to £100 and maybe 4 hours labour.

By the way, burping isn't a once a season job in my experience. I check mine every trip and always manage to get some air out - it's a mystery how it gets in though.

Simon

 

[mph]

I agree with SimonD's advice about the shaft seal. One thing to check first before forking out on a new shaft seal & fitting is the syphon break on the raw water intake pipe.
The volvo made syphon break often seems to leak and in my experience, once they start they don't stop no matter how often you clean them out.
Check the little pipe coming from the top of the syphon break when the engine is running - if there is water dribbeling down the pipe, this could be the source of your sea water - 6 hours could easily produce 2 ltrs from here.
If the syphon break is duff, change it for a Vetus unit (available from Vitesse Marine in Fareham - about £50)
If the syphon break is ok, you could check the shaft seal for seepage with the engine running and in gear by very carefully feeling under the seal - dry it out 1st and you should be able to feel any droplets if it's leaking.
Don't try this if there is any chance of a sleeve etc getting caught in the shaft....

 

[Shanty]

[ QUOTE ]
.......If the syphon break is ok, you could check the shaft seal for seepage with the engine running and in gear by very carefully feeling under the seal - dry it out 1st and you should be able to feel any droplets if it's leaking.

[/ QUOTE ]

Don't like the sound of that - fingers in close proximity to a rotating shaft is tempting fate. Instead, use some loo roll (of the absorbent variety). Dry the area under the seal with loo roll until you can't detect any moisture. Then lay a piece of loo roll under the seal. Run the engine in gear, and check the loo roll for any signs of leakage - it will show even the smallest drop.

 

[Skylark]

I really appreciate your comments but regretfully the boat is now out of the water so I can't conduct these basic tests. I only discovered the leak 2 weeks ago and that it was from the stern area just yesterday. It's probably wise to change the seal while she's out. Thanks again.

 

[Shanty]

Fair comment - advice aimed more at anyone else tempted to try mixing fingers with rotating shafts.

With the boat out of the water, you are going to find it difficult to do any leak tracing. I would agree that its probably worth replacing the seal anyway, since you know little of its history.

I've been using a Volvo shaft seal for the past three years and like them - simple, uncomplicated, and does the job effectively.

 

[Heckler]

if you can wield some allen keys, it is an easy job to do, 4 allen screws hold the prop flange to the gearbox flange, mark the edges so that they go back together in the same position. they are really tight, get a pipe to fit over the allen key to give increased leverage, i use a screw driver jammed in between an allen screw head to hold the shaft from turning. once you have the screws out, slide the shaft back and slacken the pinch allen screws that hold the flange on the shaft. hit a screw driver in the split to ease the grip of the flange on the shaft, unscrew the locating allen screw as well and then the flange should ease off the shaft. undo the two 10 mm pinch bolts on the seal and ease it off the fi glass tube and slide it up the shaft and off. put the plastic protector in the new seal with plenty of the blue grease and slide it on the shaft to the fi glass stubb, when the seal is in position remove the protector, reverse the order of undoing and that is it, make sure you lean on the allen screws, they allegedly come undo if you dont.
stu