Hello,
I want to start this thread by way of saying this is a tale of actual events without opinion or bias - I'll let others bring that to the debate.
Boat:- Grady White Tigercat x26. Motors - 2x 150hp 2009 four stroke Yamahas
During November we took the family to Northwest Island. We left from Gladstone for a 12 night trip camping on the Island. Day 4 during an overnighter east of Wilson Island (10kms east) the overheat alarms came on and shut the motors down whilst travelling between GPS points. Waited a few minutes and restarted - alarms came on again and shut both motors down. We drift fished for an hour and restarted motors - no alarm and both tell tails running fine. Headed for home at just planing speed when the starboard motor started making a noise then alarms sounded - followed by "bang - crunch" and both motors stopped. Starboard motor seized and wouldn't turn over - Port motor ran fine but with no gauges. It would seem the starboard motor was - incorrectly - wired to both gauges cause both to cut out during the alarm for the Starboard motor. Made it safely back home and found the Cat planes on one motor at about 12knots.
During the course of the next 8 days, the motor eventually freed itself enough to turn over and fire and will idle with a extremely nasty knocking noise from up high in the crankcase. I've informed the trusty local mechanic and we're awaiting options for re-power once the new supermarket is completed in a couple of months.
During investigation we found an interesting fact. The boat was fitted with new motors on the Sunshine Coast in 2009 - running serial numbers with counter rotating props. Port motor went "Bang" during first or second sea trial and was swapped out completely by Yamaha. It had under 10 hours on it. It would seem five years later it's partner motor went bang with 380 hours on it.
Boat: 2007 5m Brooker Discoverer open dinghy. Motor 2007 F60 Yamaha 4 stroke.
Over the weekend I had the tinny tied to the pontoon and the young fella had some friends around who wanted to go for a quick tube. Tied on the single tube and ran them around for a couple of hours. Not far from the house and near the local public ramp the revs die suddenly on the motor followed by a noticeable crunch and a large bang followed by silence. No alarms - tell tale was working fine 30mins before (can't be positive it was working at failure point because I wasn't looking at it). Motor completely seized - turn of key met with a click only. Prop will turn so it's not a gearbox issue but from up high in the crankcase. Tow back to ramp and back in the yard. Mechanic informed and laughs a lot and will look for a diagnosis in the near future. Motor has between 200-300 hours on it.
Both motors serviced every year whether they do 100 hours or 10. Some years the boats don't do a lot. Up until this point I have had not one sign of trouble - never touched anything on any of the three Yamahas other than impellers etc at regular change.
Adding to the irony is the Bayliner Capri wakeboat is currently in the backyard out of action because it's chewed out the spline on the prop. The only boat still going in the Bugg household is the 9 foot dinghy belonging to the young fella with a 4hp HONDA 4 stroke.
It's fair to say I'm not having a good run at the moment but the coincidence of Yamaha detonations in my first hand experience (3 from 4 motors) is starting to get a bit annoying.
Regards
Brett