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Old 06 September 2015, 14:31   #1
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Country: UK - England
Town: River Exe
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Help: apparently I need a new gearbox shaft

Hi,
I took my 5.4m Rib with 80hp Yamaha 4 stroke into a boatyard for an unrelated reason and was told that I must have hit something and needed a new gearbox shaft and seals. The only time I remember hitting something was going about 4 knots and hitting the mud so was surprised there was such damage.

I was quoted over 2000 +vat + labour for a new gearbox which was a bit of a shock. They said it was a risk just changing the shaft and I would be better with a new gearbox. Does this sound right? Would it be too risky just to change the shaft? Any idea how much this might cost? They also said they had an outboard for spares and could sell me a whole gearbox for 1750 +vat + labour instead.

I'm afraid this is an area I know nothing about so would be really grateful for any help about whether this price seems right, or if there's any way I could get this done cheaper. I am worried I am being ripped off here!

To be more specific, I wrote down the following about what they told me:


At some time the prop has hit something. This has resulted in a bent gearbox shaft. As the shaft is slightly bent there is vibration in the gearbox. Which in all probability will lead to water getting past the rubber seals and getting into the gearbox oil. Another problem caused by the vibrations in the shaft is that the prop is becoming damaged by cavitation there is evidence of this but so far the damage is only slight. However in time the prop blades could be badly damaged. In the short term the engine could still be used although the gearbox oil should be changed. However in the long term either a new gearbox shaft and seals would have to be fitted or a totally new gearbox would be needed. The boatyard. have an almost new second hand gearbox off another engine available and fitting this might be more economical than putting a new shaft in the existing gearbox.
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Old 06 September 2015, 14:49   #2
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What, if anything, have you noticed?
Could you fit a lower unit yourself?
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Old 06 September 2015, 14:53   #3
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I hadn't noticed anything at all hence the surprise. Although if I think about it I do notice that after using the engine for a few hours when it is in low revs or idling I can hear a faint whistling sound...no idea if this is related. I only bought the boat a few weeks ago so not sure what noises are 'normal'.

Boatyard said there was some water in the gearbox oil.

My main concern is being ripped off as I'm a 26 year old girl as therefore probably an easy target!
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Old 06 September 2015, 15:00   #4
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Sounds like there taking the pish I had the oil seals done in one of mine circa 300 and that was with other bits as well get a second opinion
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Old 06 September 2015, 15:02   #5
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You certainly need at least a second if not third opinion. I'm sure some locals will comment with recommended workshops to get it checked out.
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Old 06 September 2015, 15:04   #6
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And look for second had if replacement needed
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Old 06 September 2015, 15:05   #7
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Sounds outrageous! Get it out of there. It's a bit of a haul for you, but OSM at Lostwithiel are very professional and super fair. They'll only hit for what is necessary rather than piling it on. My Etec is with them for a service currently.
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Old 06 September 2015, 15:09   #8
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I ran an 85 2 stroke for years with a bent propshaft & it never caused a problem I checked the oil colour regularly just in case a seal did fail as it is a possibility but mine never did I had the engine for about 5 years & it saw lots of use
If it's do slightly bent you can't feel it I'd keep an eye on the oil colour & just use it maybe look out for a good used box but I'd say sub 500 for a good used box isn't far away
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Old 06 September 2015, 15:10   #9
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If I had hit something hard what would the likely damage be?

New prop shaft? New gearbox shaft? (is it the same thing?). Would I ever need a new gearbox shaft? Their answerphone message said it could have damaged the bearings and hence a new gearbox would be safer? Is this reasonable?

They have offered a whole new gearbox and shaft etc for 1750+vat+labour. Do I need to enquire about the origin of this second hand one?

Do you think the whistling might be related to this or not?

Thanks again so much for everyone's help- so much appreciated.
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Old 06 September 2015, 15:11   #10
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If they say there's some water in the gearbox oil does this suggest it could be bad?
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