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Old 27 December 2009, 01:49   #1
Country: Other
Town: Muscat
Boat name: Abdul Aziz 3
Make: Libra
Length: 6m +
Engine: 2 x Yam 75 OB
Join Date: Sep 2007
Posts: 82
Yamaha Forward and Reverse Gears

I have 2 x Yama 75hp (Serial 411849 and 411853) on a Libra 6500R RIB. Both engines clunk into gear and I have been advised that this normal wear on older engines and that the solution would be to replace forward and reverse gears and sliding clutch. Engines have about 800hrs and have been serviced every 50hours. Main use of boat was yacht racing safety boat.

My questions are:
Does this sound like a reasonable diagnosis and solution to the problem?
If so are there any other parts it would be wise to replace with gearcase open?
Finally do you have any recommendations where to buy cheapest parts, UK, USA or anywhere else as I will have to import them into Muscat anyway.

Happy New Year and safe boating

Andy Young2 is offline   Reply With Quote
Old 27 December 2009, 07:34   #2
Country: UK - England
Town: Surrey
Length: no boat
Join Date: Feb 2009
Posts: 215
hi there , have you checked your cables and set up ?? if you disconnect the cables from the engine and put it into gear manually without the cables does this help at all. this is the first step i would take . let me know before we go any further . barry

outboardtech is offline   Reply With Quote
Old 28 December 2009, 03:12   #3
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,538

When you say "clunk" do you mean it makes a "big solid thump" as it engages, or do you get a kind of rattling "thud-thud -THUD "CLUNK" as it engages?

I'm thinking that as it's had a mostly rescue boat life, the engines will have performed a lot more engagements of the grears than, say a cruising or fishing boat.

As OBT says, check your linkages. If it's a big solid over loud "thud" you're getting, check the engines' idle speed (and clean / re- lube your throttle linkages). IA single loud thud would imply too high an idle speed.

Multiple thuds before full engagement is as OBT says, gear linkage slack or your dog clutches' teeth are worn, in which case you;ll need the whole set of gears, otherwise you'll have new teeth on the clutch & worn on the gears.
9D280 is offline   Reply With Quote

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