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Discussion Starter #1
I was working the engine pretty hard and I lost forward. Still have reverse.

From the service manual it looks like a pretty simple gear box. What level of mechanical expertise should one have before taking this on?

Thanks
 

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To continue with my above post, years ago I had a old beater Ford pick up truck that the tranny went out on me. I got a quote for a rebuild, but having 4 kids at home I could not justify the cost, However the truck was very handy when you need one. In my spare time I pulled the tranny and open it up, and found out all I needed was to replace a shift dog. If I remenber right it was $50 and my time. If couldn't fix it, then it was going to the tranny shop when I got the money. I allways wondered, If I took the tranny shop first would they told me it was only a $50 fix.
 

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Discussion Starter #5
This is not the cable. It's not stuck in reverse. It goes in and out of neutral just fine.

In forward it just slides in with no resistance, suggesting the gear or some interanl linkage is toast.

I am pretty comfortable tearing machines apart but marine transmissions are new territory.

Any yanmar transmission gurus out ther?

thanks
 

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Remove the transmission inspecation plate and take a look inside to see if you see anything broken. If nothing is visible manually move the shifter from reverse to forward and compare what you see in each position. That might give you an idea where to start. If you see something that doesnt look right take a photograph of it and show it to the parts person at your local Yanmar dealer.
 

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Lynger1
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Hi hertfordnc
I have Yanmar 2gm 25Hp inboard
At one stage my reverse was stuck could not get it out only by stopping moter and with some force
Remedy
take off gearbox put on workbench open up in steps clean all parts and housing cheueq sleeves and put it back together with proper gear oil

In my case the problem was fine rubbish in oil and sump of gears

I dit not have anny problems for over 4 years but i replace oil every 300hours

Hope this wil help you job is very simple to do
Good luck
 

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Discussion Starter #8
more info

i went back to the boat today. it was flat calm at the dock. I put it in gear and there was forward motion. No power, I gave it throttle and it just pushed the boat a little against the mooring lines.

So now I'm thinking it's the cluthc or friction plates. And apparently there is a different one for forward and reverse.

Teardown looks pretty simple from the service manual but I'd love to hear form someone who has done it.

thanks
 

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Lynger1
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Hi Just remove gaerbox and open up like isaid before
inspect ,clean you wil sea if clutch is worn
If so order new one and replace
Saving you lots of money and you know how to fix this
 

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Try This

I would replace oil with Mystery Oil, and shift into Forward, Neutral, Reverse, and repeat for 30 Minutes or so...then replace with new oil....works alot of the time..........Hope this helps:)
 

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Discussion Starter #11
I would replace oil with Mystery Oil, and shift into Forward, Neutral, Reverse, and repeat for 30 Minutes or so...then replace with new oil....works alot of the time..........Hope this helps:)
Are the clutch plates wet with oil?
 

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Discussion Starter #14
Is there an exploded view of the clutch available?

I do have an exploded view but i can't upload it from here. I am pretty certain the diagnosis is worn or glazed friction plates and I have read several suggestions for treatment; Marvel Mystery Oil, Automatic Transmission Fluid and Mineral Sprits.

I don't have anything to lose.

I would be grateful for whatever other suggestions anyone may have.
 

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I guessing they are clutch packs like a motorcycle or automatic transmission but I'll wait untill I see a pic.

Is there an exploded view of the clutch available?
 

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Discussion Starter #17
picture of trans uploaded

i couldn't really tell what I was looking at in this drawing but here is the exploded view of the trans.

gear

dave
 

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transmission

I guessing they are clutch packs like a motorcycle or automatic transmission but I'll wait untill I see a pic.
I believe you are correct.....at least that is how they appear...I have also heard of the Mineral spirits treatment. I would deff try one of those routes, as the cost is small, and a good chance it will "heal" your problem...I hope this helps:)
 
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