Klack-klack-klack goes the Transmission

[zachduckworth]

Hi,
I have a Yanmar 2GM20, with 650 official hours on it but I'm not sure of that really because if you turn the power off the odometer stops counting...

My boat has, over the last year or so, begun to make a clunking sound when I shift from neutral to forward or reverse. A few times when going into reverse it will make a "klack sound" before it catches. This often happens when I am mooring in a slight swell and I shift quickly from forward to reverse. I have a Vetus control, so one stick in the cockpit shifts gear when you move it from neutral to forward or reserve, then it allows acceleration.

This past weekend when mooring I put my boat into a quick reserve from neutral to come to a standstill so the mooring ball could be picked up. When I did this I got about 6 quick loud "klacks." I went into neutral, then back into reverse an it immediately shifted without any klacks.

That was the most klacks I have got at one time. I am concerned that I have some sort of transmission issue brewing. I have also recently found some oil on the bottom of the transmission case.

Any idea what this could be? Could it be the transmission cone? Something else? Should I be concerning removing it and having it rebuilt? Is it easier just to buy a brand new one and install it given labor? I prefer to overreact now while the engine is working rather than have some transmission failure when I'm in a crowded mooring field or coming into my slip. Any advice is appreciated.

[CSY Man]

Check the throw of the shifter arm, perhaps your cable needs adjusting?
I am sure you already checked the fluid level..

[SailingHarmonie]

Originally Posted by zachduckworth

Hi,
I have a Yanmar 2GM20, with 650 official hours on it but I'm not sure of that A few times when going into reverse it will make a "klack sound" before it catches. This often happens when I am mooring in a slight swell and I shift quickly from forward to reverse.

When you say you shift “quickly” from forward to reverse, do you realize that is really bad for many parts of your drive train, especially the transmission?

If you do this as a matter of routine, without pausing in neutral for the engine and prop to slow down it could easily result of internal mechanical damage that is the cause of your issue.

If you are lucky, and you haven’t damaged the transmission by doing this, the symptoms you see are usually caused by inadequate throw in the cable. The easiest test is to disconnect the cable and try shifting by hand. It everything is fine when you do that, adjust the cable to the specifications in the engine installation manual.

[s/v Jedi]

This reminds me of my cone clutch gears not engaging because of glazing. I had to take it apart and lap the surfaces.

[Turtle Blues]

Have you inspected the damper plate?

[SailingHarmonie]

Originally Posted by Turtle Blues

Have you inspected the damper plate?

A good thought!

But does anybody ever "inspect" a damper plate? If I am going that deep in and even suspect it might be old, I just have a new one to drop in. I doubt I ever pulled a transmission off an engine and did not replace the damper plate. They usually aren't too expensive, and are such a pain to get to, if I am looking at it, I am changing it!