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Old 26 June 2013, 03:58   #1
Country: UK - Scotland
Length: 9m +
Join Date: Jan 2009
Posts: 2
yamaha 350hp snapped crankshafts

Just of the phone to yamaha uk customer service and am not happy,I run a pair of yamaha 350hp fourstokes on an arctic 28 rib for diving support.2 months ago one engine started making a rattle,dealer thought it may be dropped valve so head off to find every thing ok.engine runs sweet check out so big strip down to find fault In USA there had been mention of crankshafts snapping and yamaha did recall on flywheels suggesting it was the fault .My engine fitted with later improved flywheel but crank still snapped in half,after 7 weeks of downloading data and sending it to japan yamaha now state extreme use caused failure,download hour total 599,480 on tickover,80 on 3000 to 4000rpm cruising speed 20 on 2000 to 3000 off plane speed ,no warnings logged when crank failed,oil pressure 69psi with snapped crank .Attitude of yamaha customer service is shocking out of warranty so can see from video stress cracks or casting cracks around centre main journal.there is no evidence of oil starvation or overheat so its pretty obvious the fault lies in the crank.So all yamaha 350hp owners out there beware you may have a problem just waiting to develop.I have run yamahas for 30 years ,this one will be the last.

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Old 26 June 2013, 08:27   #2
biffer's Avatar
Country: UK - England
Town: swanwick/hamble
Boat name: stormchaser
Make: custom rib
Length: 8m +
Engine: inboard/diesel
Join Date: Aug 2007
Posts: 3,848
We had this with Yamaha must be 10years plus ago, the sti me 421 had an electric lift pump too prime the engine, it was crap and to fine a micron, it used to emulsify the fuel and blow the cold start piston out the side of the injector pump, Yamaha said definitely not there problem until the guy started to sue them, guess what the me22 didn't have a pump when it came out, same with exhaust elbows, we started making our own out of stainless, guess what, they started to produce stainless ones.
I'll start to sue them and there attitude should change
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