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Old 24 April 2013, 15:32   #1
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Cracked prop housing

At some point prior to my ownership someone has knocked the prop housing causing the aluminium to crack along the side for about 2 inches. It all seems to work fine still and the crack has not opened up in use but I still would rather have it repaired. Any suggestions who can do this or how to do it? I have been considering Technoweld.
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Old 24 April 2013, 15:49   #2
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Old 24 April 2013, 17:19   #3
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Not sure if they do the housing (gear case) or just the prop but have emailed them to find out. Thanks
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Old 24 April 2013, 19:16   #4
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It could be a specialist job as the welding might distort the gearbox and alter the alignment of the bearings and drive shafts within. It might be worth opening the crack up slightly with a dremmel and back filling it with an epoxy of some description unless you're worried about a sudden failure due to the weakened integrity of the casing. Where is the crack exactly? On the gear case or on the skeg? Posting pictures might help.
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Old 25 April 2013, 00:28   #5
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Sorry misread your post thinking it was on the prop hub or something
Thought it was a bit odd for a prop to damage there
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Old 25 April 2013, 01:04   #6
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I used a firm local to me Amac Engineering in Northallerton North Yorkshire to repair the cavitation plate on my outboard. Brilliant job & very reasonable pricing. They specialise in welding car cylinder heads etc so it's obviously possible to avoid distortion etc but you'd definitely have to strip the gear box of all internals & seals before you start.
I'm not suggesting that you use Amac but there may well be similar firms in your area if you google your local towns. I did all the prep & finishing on mine to keep costs down.
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Old 25 April 2013, 03:35   #7
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Thanks for all the info. Not the best picture but its all I could find.
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Old 25 April 2013, 03:40   #8
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Hmmm that's roughly where the seal is. Might be worth checking your gearbox oil for mayo a little more frequently than normal......

Other option of course is I think that gearbox looks Yam (i assume form your info it;s a Yam 85?) From memory that gearbox is shared with most of it;s age between about 50 & 90 Hp, so you might be easier with a new gearbox?
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Old 25 April 2013, 03:43   #9
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It is a Yamaha 85. More money!!!
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Old 25 April 2013, 04:40   #10
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Chase out the crack a little with a grinder and use an epoxy metal repair compound.
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Old 25 April 2013, 04:47   #11
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I considered that too. Will the epoxy not just drop out with any flex though as from experience it never bonds particularly well with the metal?
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Old 25 April 2013, 04:59   #12
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I would have thought the first this to have a look at is the gearbox oil. If its emulsified then your letting in water and you'll need to repair or replace your box.
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Old 25 April 2013, 05:21   #13
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Quote:
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I considered that too. Will the epoxy not just drop out with any flex though as from experience it never bonds particularly well with the metal?
So long as it's the right stuff for the job and has a good key to grip.
JB weld products are the best ones I've used.
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Old 25 April 2013, 06:11   #14
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Will the epoxy not just drop out with any flex
If there is any flexing of this "crack" you are stuffed before you start.

BTW expoxy adhesives are the dogs b*ll*cks when bonding to metals when properly applied.
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Old 25 April 2013, 06:31   #15
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Common problem with Yam boxes.
http://www.rib.net/forum/f10/crack-t...ent-25161.html
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Old 25 April 2013, 13:40   #16
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Common problem with Yam boxes.
Yep, usually when they haven't been flushed properly for long periods.


The only solution is (assuming the crack hasn't got as far as the seal) to drill a VERY small hole at the end of the crack (this stops it from cracking any further) , grinding the crack out very slightly with a slitting disc and filling it with JB weld (JB weld does stick).

Don't use the 'rapid' version.
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Old 25 April 2013, 14:36   #17
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to drill a VERY small hole at the end of the crack (this stops it from cracking any further) , grinding the crack out very slightly with a slitting disc and filling it with JB weld (JB weld does stick).
Don't use the 'rapid' version.
Exactly what he said
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