Fitting a Volvo prop shaft seal - any hints or tips?

[sgr143]

I need to replace the prop shaft seal this winter; it's of unknown age (at least 4 years, since that's how long I've had the boat), the rubber is very stiff and inflexible, and it's just started to dribble a bit. Best done before next season, I think.

But... I've never done this sort of job before, and I'm rather wary of it. I don't want to have the boat launched next Spring (Wicor do it in absentia nauta) and soon after come down for a first jolly, only to find just a mast sticking out of the water.

The instructions (attached) are fairly clear, though I'm a bit puzzled as to why one is supposed to put the protecting plate (part 3) under the clamp at step 8 rather than earlier (step 4, figure 5?).

But any hints and tips would be very welcome! I really want to get this right first time.

Thanks, Steve

 

[Gwylan]

Not difficult, well I managed it.

But really go for the Radice version. Lasted much longer than the previous Volvo ones.

https://www.sillette.co.uk/price_pdf_files/deep_sea_mane_craft_shaft_seal.pdf

But we were on a drying, sandy mooring.

Would need to feel very confident about the launch team if I was not going to be there.

 

[sgr143]

Thanks Gwylan - I bought the seal (a Volvo one) last year but was too timid to fit it! The crew at Wicor are very good, but I might see if they can possibly notify me of the actual launch day so I can travel down (I live about 80 miles away).

 

[Roberto]

Have you a similar seal now, similar to the Volvo one?
Just asking because they need perfectly concentric shaft and hull tube, if it is not the case then one needs a different type of seal.
I bought a Volvo seal, but on trying and fit it I discovered there was a tiny "un-axiality" between the shaft and the hull tube which made it unusable, so I had to go for a PSS seal (which I am very happy of).

 

[Pete7]

Steve, when was the last time the prop shaft to gearbox coupling came off. That may need some days of soaking with WD40 or equivalent before you start. Also check to see if there is a roll pin or bolt right through the shaft. Don't loose the Volvo red seal protector which is used to protect the lip seals. Ours lives on a nearby engine hose. Use the genuine volvo grease.

Use a Mac Donalds straw to get the grease in, much easier.

If you can't get the large S/S clip done up, use a longer bolt in one hole to pull the edges together, put the other bolt in, then go back and replace the longer bolt with the volvo original.

Don't put the seal on an area which the old stuffing gland sat. I needed a new prop shaft due to the smooth but worn areas used over the years from stuffing glands.

Pete

 

[eddystone]

Whether there is a pin or not, separating the shaft from the thing attached to the gearbox can be awkward. Having undone the bolts I had to force the two halves of the collar apart with wooden wedges before the shaft would slide out. Also can’t remember the details but there is a knack to getting the split in the lip protector to open up - otherwise when you insert the shaft it just pushes the protector out.

 

[Bobc]

It's quite simple to fit.

Give the shaft a good clean and polish to make sure it's perfectly smooth before fitting the new seal (I went over it with 1000 wet & dry and then polished it with a cloth polishing wheel on a drill).

Make sure you use the protecting sheet to cover the lip seals. They are very delicate and you don't want to damage them.

When you put the boat back in the water, don't forget to burp the seal. You need to get all the air out.

That's about it really.

 

[vyv_cox]

There is a page on coupling types and removal on my website at Coupling types and removal

Removal is quite straightforward using the method I describe.

 

[dje67]

Did mine a couple of years ago and it was easy. All the advice above is good. The additional issue I had to deal with was that when I took the old seal off I found that the height of the rear of the engine was wrong. This then caused the prop shaft to enter the stern tube below the centreline. I suspect that was what caused the old seal to start leaking as the shaft was effectively pushing down on the seal. Anyway, I had to spend a happy morning realigning all 4 engine mounts to get the shaft at the correct height and angle entering the tube.

 

[sgr143]

Thank you all for your help.

Roberto - it is replacing an existing identical seal, so I hope the alignment will be OK.
Vyv - what I have is the Bukh type (thanks for the useful ling and page). Useful to know that I have to withdraw the bolts completely. The method looks very useful - a kind of do-it-yourself inverse sprocket puller, if that makes sense! I'll probably have to soak the gearbox-to-coupling flange bolts in oil for a bit before they will loosen easily (I already did that for the clamp bolts, Pete 7, and they are now freed off and ready to fully withdraw.)

As regards burping the seal (a task fora marine biologist involved in a pinniped breeding programme?).. well, thereby hangs a tale.

There is a manufacturer's sticker still on the main electrical panel on the boat telling me in no uncertain terms to do just that every time the boat is put back in the water. Despite that, on my first trip in the 2018 season, I forgot to do it. I remembered as I was in the car, 10 miles into my trip home, in one of the most god-awful thunderstorms I've ever been in (we'd been running just ahead of it in the boat on the way back from the IoW). I live about 80 miles away from the boat, and wouldn't be back for maybe a couple of weeks. No choice really but to turn round...

I arrived a the boatyard at about 10pm with the storm still going full tilt. It's a 10 minute walk out to the end of the jetty, so I waited for a small lull, then grabbed the outboard and trogged out to the end... to find the tide at LWS. Yes, I should have known that... Off to the pub for a dragged-out half pint, then back in the car to do a crossword before heading out in the dinghy at midnight, by which time the storm was cracking on in full Frankenstein climax mode. Quite a wild trip.

The seal (which I burped and put some kitchen paper under to check for leaks overnight) looked fine, and next morning I found there had been no ingress of water at all... Still, better safe than sorry.

 

[sgr143]

Update on this.

I tried the Vyv Cox method, but the propshaft would not budge from the clamp fitting, despite the clamping bolts being fully slackened off and oil and WD40 having been liberally applied to the coupling over the winter. I tightened the "pulling" bolts very hard - to the extent that I was worried that any more might break the gearbox output flange. Possibly local heat would have helped, but I wasn't about to start waving a blowtorch around in the engine compartment, not that I had one to hand anyway.

In the end, given that with the coupling disconnected at the flanges, the propshaft could now be moved in and out of the seal, I used that movement to work a lot of grease into to the seal, bolted the flanges back up again, and called it "job done" for now. I'll have another go when the boat is out of the water again next winter, maybe with a paint-stripper heat gun to see if that can help free off the compression joint.

[ Edit - <face-palm moment> - I've now looked again at the info kindly provided by Vyv at Coupling types and removal and find that I should have taken the coupling bolts out altogether, as they locate into grooves in the propshaft (Bukh engine). That serves me right from working from memory! Next year... ]

hey ho.

Steve