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Old 01 May 2004, 08:39   #1
nik
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Yanmars

I have been raking over the coals of the cheap yanmars thread below,

Cheap Yanmars

I am still puzzled over some items. If yanmars suffer from cracked blocks, and the yanmar block is the same as the yamaha block, which is the same as the toyota landcruiser. Then why dont yamaha suffer the same problem?
Also, I have heard no bad comments about the yamaha leg. Is it better than the bravo's? Can it be bought separately?
I must admit the bravo legs seem a real liability. I dont know how much warning you get before it fails completely, or if it is a sudden failure.
Its a shame there is not more choice in this area.
Nick.
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Old 01 May 2004, 15:09   #2
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From what I can gather it is more the application that causes the problem - a Yanmar in a Sunseeker has a much easier life than in a Rib - also the Yamaha units are lower hp so don't stress the drives as much - but I am NOT speaking from experience so take with a pinch of salt!
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Old 01 May 2004, 16:01   #3
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Nick,

I just spoke with another Yanmar owner who's suffered a cracked block this week. He's done some investigation into the problem and found that they all(?) crack in the same place - near an engine mounting. The mounting in question uses three bolts, whereas the mounting on the other side uses four bolts. Also, he tell's me that there are internal oil colling galleries running close to this point. Apparently four bolts could have been used, but Yanmar have mounted some of the external components close by. I don't know if Yamaha do the same. He also tells me that builders such as Mark Pasco move these components and modify the mounting.

Yamaha drive legs do go - just read Alan Priddy's book to find out how many he broke going around the world. Also leisure users have suffered drive failures. Jim Mackintosh (BIBOA secretary) would be a good source of information.

All 2nd hand info, but HTH.
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Old 01 May 2004, 17:51   #4
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Alan Priddy

To be fair Alan got excellent life from his outdrives at least one of his problems were collision related, look at the mileage he done, its not a fair comparrison
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Old 01 May 2004, 18:51   #5
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What's not a fair comparrison, Gavin? If you read Alan's book you'll be able to work out the MTBF for the outdrive legs. You'll also be able to find out Alan's analysis for the reason of the failures. You could also ring up Jim and I'm sure he'd be happy to give you his view on the situation from a leisure point of view as well.

The Yamaha Hydradrive is very nicely engineered, but if you think it's perfect, then you're looking through either rose tinted glasses or beer goggles!
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Old 02 May 2004, 05:25   #6
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Originally Posted by Richard B
What's not a fair comparrison, Gavin? If you read Alan's book you'll be able to work out the MTBF for the outdrive legs. You'll also be able to find out Alan's analysis for the reason of the failures. You could also ring up Jim and I'm sure he'd be happy to give you his view on the situation from a leisure point of view as well.

The Yamaha Hydradrive is very nicely engineered, but if you think it's perfect, then you're looking through either rose tinted glasses or beer goggles!
I like Hydradrive legs as they are very smooth. I can't comment on the reliability however.

The Yanmar/Yamaha block is Toyota Landcruiser 4.2 block. In it's road form it produces around 130 hp The Yamaha engine produces around 240/280 and the Yanmar in excess of 300hp. I personally believe this might have something to do with engine reliability. If the engine is light and has a high horsepower then it'd likely to be low on torque. If you put it into a high torque application like pushing a big cabin cruiser ...wouldn't that cause a problem ?

re legs my understanding is that Mark Wildey has a Bravo three with a shower attachment and I think that's worked well for a while? I don't think Hydradrives can handle much power over 280.
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Old 02 May 2004, 05:42   #7
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Interesting discussion, given that I'm awaiting repair of my Bravo 3 (see Bravo 3 thread).

Does anyone have info on the reliability of Volvo engines and legs? Perhaps the new D3s will offer more in terms of reliability on RIBs?
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Old 02 May 2004, 05:47   #8
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Toyota Landcruiser 4.2 block. In it's road form it produces around 130 hp
Bit more, actually Stuart. The 4.2 does 201hp, (the 4.7 v8 does 235hp).
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Old 02 May 2004, 06:26   #9
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It's the D6 you'd need, Jim. The 300hp one. It looks good but it weighs 380lbs more that the KAD 300. There's always a catch.
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Old 02 May 2004, 17:08   #10
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Bit more, actually Stuart. The 4.2 does 201hp, (the 4.7 v8 does 235hp).


Did you know that or look it up?
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