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30 August 2015, 18:35
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#1
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Member
Country: Ireland
Town: Kerry
Boat name: Independence
Make: FunYak
Length: 4m +
Engine: Honda BF10
Join Date: Jun 2015
Posts: 123
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Yamaha F30 overheated :-(
Feck sake, finally got out on a calm day and engine overheated on the way home , wasn't on full throttle either, only 4000 revs when she started smoking out the top exhaust, couldn't Rev it over 1800, turned it off when the pee stream started to become spluttery,
Flushed it out since getting back and it started on the muffs first turn, pee stream strong as always
What do you think happened? Water pump? Or thermostat ?
Help :-(
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30 August 2015, 18:47
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#2
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Member
Country: UK - Scotland
Town: wormit
Boat name: lots of them
Make: various
Length: no boat
Engine: all types
Join Date: Dec 2004
Posts: 632
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Impeller key
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30 August 2015, 18:58
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#3
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Member
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
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Kelp or bag blocking the intake?
jky
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30 August 2015, 20:47
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#4
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Member
Country: Ireland
Town: Kerry
Boat name: Independence
Make: FunYak
Length: 4m +
Engine: Honda BF10
Join Date: Jun 2015
Posts: 123
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I took the intake guards off and found nothing, there was a little bit of debris in the pee hole exit, but the pressure is good , if the thermostat doesn't open would that cause the overheating?
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30 August 2015, 21:02
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#5
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Member
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,767
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If the thermostat doesn't open yes it would overheat. I'd want the stat out and checked.
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30 August 2015, 21:07
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#6
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Member
Country: Ireland
Town: Kerry
Boat name: Independence
Make: FunYak
Length: 4m +
Engine: Honda BF10
Join Date: Jun 2015
Posts: 123
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Ok, when it was getting serviced and a new timing belt the mechanic said he checked the thermostat !
Worse case how will I know if there's damage done?
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30 August 2015, 21:16
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#7
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RIBnet admin team
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,632
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Davie is a man of few words built on many years experience. I'd follow his pointer first.
As for long term damage compression testing and possibly a boroscope would help, but personally I'd want an expert to look at it.
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30 August 2015, 21:39
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#8
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Member
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,767
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Sorry just though - you tested on Muffs. I've never used muffs. Would there be water flow even if the impeller failed? If so then water flow means nothing.
Testing in a bucket would confirm that as if the paddles on the impeller are missing or the key has failed and the paddles are just spinning freely. BUT testing in a bucket with failure would result in potentially more damage...
Your mechanic who checked the thermostat presumably also checked the impeller?
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30 August 2015, 22:01
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#9
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Member
Country: Ireland
Town: Kerry
Boat name: Independence
Make: FunYak
Length: 4m +
Engine: Honda BF10
Join Date: Jun 2015
Posts: 123
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I'll take off the lower unit tomorrow and see what the story is...
No confidence in the mechanic or the guy running the dealership
Looks like it's not my year , off the water for awhile :-(
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30 August 2015, 22:43
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#10
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Member
Country: UK - England
Town: Leicester
Length: 5m +
Engine: 135hp Mercury
Join Date: Sep 2013
Posts: 1,431
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Quote:
Originally Posted by ShinyShoe
Sorry just though - you tested on Muffs. I've never used muffs. Would there be water flow even if the impeller failed? If so then water flow means nothing.
Testing in a bucket would confirm that as if the paddles on the impeller are missing or the key has failed and the paddles are just spinning freely. BUT testing in a bucket with failure would result in potentially more damage...
Your mechanic who checked the thermostat presumably also checked the impeller?
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My Mercury doesn't put water out of the tell-tale with just a hosepipe connected to the muffs unless the engine's running. Turn the engine off & the telltale stops.
Check the stat.
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30 August 2015, 23:04
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#11
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Member
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,767
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Quote:
Originally Posted by paintman
My Mercury doesn't put water out of the tell-tale with just a hosepipe connected to the muffs unless the engine's running. Turn the engine off & the telltale stops.
Check the stat.
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Yeh - but your impeller would stop the flow as its not turning. But if the impeller is damaged water can flow past, or if the key is damaged it can spin on its spindle.
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30 August 2015, 23:54
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#12
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Member
Country: UK - England
Town: Leicester
Length: 5m +
Engine: 135hp Mercury
Join Date: Sep 2013
Posts: 1,431
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The impeller would act as a plug.
If the key is damaged/missing the pump drive shaft will be turned by the engine but not pump water as the impeller isn't turning & blocking the water supply so I doubt if you'd get any water from the telltale.
If there was no impeller in place or a number of its blades are badly damaged or broken then I expect it could be possible for water to reach the top of the engine on muffs when not running.
Be interesting to see what would happen with the OPs if run in a bucket. Or what he finds when he drops the gearbox to check the impeller & key.
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31 August 2015, 08:58
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#13
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Member
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,767
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If the key is missing /broke ... Why would putting water in the intake at pressure (I.e muffs) not just spin the impeller on the shaft and allow water past?
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31 August 2015, 09:13
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#14
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Member
Country: UK - Scotland
Town: wormit
Boat name: lots of them
Make: various
Length: no boat
Engine: all types
Join Date: Dec 2004
Posts: 632
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Dont know why but I have had 3x F30/40 keys shear this year I have never seen a key snap for years. They seem to wedge in at idle but lose drive anything over 1500 rpm.
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31 August 2015, 09:17
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#15
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Member
Country: UK - England
Town: Leicester
Length: 5m +
Engine: 135hp Mercury
Join Date: Sep 2013
Posts: 1,431
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Going on my own engine & its impeller I'd be very surprised if domestic water pressure could turn the impeller. The blades are very curved when in position.
Plus the muff cups are flexible to allow them to conform as well as possible to the water intake & consequently don't form a waterproof seal in the way that a screw in adapter would, water can escape round the edges. I use the muffs for flushing only as per the instructions in the manual. If I want to run for extended periods or at higher revs then I use a cut-in-half plastic 55 gallon drum.
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31 August 2015, 09:18
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#16
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Member
Country: UK - England
Town: Leicester
Length: 5m +
Engine: 135hp Mercury
Join Date: Sep 2013
Posts: 1,431
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Quote:
Originally Posted by Davie
Dont know why but I have had 3x F30/40 keys shear this year I have never seen a key snap for years. They seem to wedge in at idle but lose drive anything over 1500 rpm.
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Bad batch?
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31 August 2015, 11:26
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#17
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Member
Country: UK - Scotland
Town: wormit
Boat name: lots of them
Make: various
Length: no boat
Engine: all types
Join Date: Dec 2004
Posts: 632
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Quote:
Originally Posted by paintman
Bad batch?
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All on pre fuel injection
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31 August 2015, 12:55
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#18
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Member
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 7,532
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The impeller is larger than the pump housing that's why you have to rotate in the direction of the shaft so the vanes lean back hence the resistance caused will prevent tap pressure spinning the impeller unless it's completely shot then the bits of rubber go up the waterways had it happen to one at work resulting in overheating if the engine has stood a while with an old impeller it could have work hardened and broke up best to strip the leg off have a look. Look on you-tube for D-Rays shop impeller service.
Cheers.
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31 August 2015, 21:32
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#19
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Member
Country: Ireland
Town: Kerry
Boat name: Independence
Make: FunYak
Length: 4m +
Engine: Honda BF10
Join Date: Jun 2015
Posts: 123
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Pictures tell a thousand words as the saying goes....
Mechanic said he checked the thermostat and it was fine, don't know wtf he checked but it certainly wasn't fine!
Don't have a kicker engine yet but because the engine was freshly serviced by my local Yamaha dealer and had a new timing belt, I felt I'd be safe enough to take the kids for a quick spin, after it overheated it took me over an hour rowing to get back, fairly pissed off now... :-(
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31 August 2015, 22:39
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#20
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Member
Country: UK - England
Town: Birmingham
Boat name: Sparrowhawk
Make: Osprey
Length: 5m +
Engine: Yamaha 90hp 2T
Join Date: Apr 2010
Posts: 215
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Send him the picture asking what he actually checked
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