Help! My transmission won't go into gear

[BobL]

I have a yanmar 1gm10 with 800 hours on it. Tried to back out of slip the other day and the tranny won't go into gear. (No forward or reverse) Checked the linkage and all that it ok. Never heard any "clanking" or "grinding".

Anyone else ever have this problem?

Puzzled
BobL

[four winds]

By "OK" do you mean you observed the lever on the transmission move forward and aft. Or mearly that it is still connected?

Has anything been worked on lately, near this area or at the controls?

You could try removing the cable at the tranny and operating the lever by hand to verify something in tranny is amiss. If it works by hand then the problem lies in the cable or its adjustment.

Also could be the cable came off at the control end. Not sure which end or both you have inspected.

[SkiprJohn]

Yes, check the lever arm on the transmission itself to see if it moves when you move the forward reverse control. If it does then check to see that the nut holding that lever arm is tight. Also check oil in your transmission.

[BobL]

Yes I disconnected the linkage at the lever and it moves both ways but doesn't engage the gears. Never Thot about the fluid. Will check that in the morning.

Thanks for the replies.
BobL

[BobL]

So I found the trans empty of oil. Put some in and it leaked right out around the shaft entrance. Big job replacing that seal???

[lesterbutch]

I had the same thing with the same engine, just last week! Mine turned out to be the shaft backed out of the coupling. Put it back in and properly tightened it and off we went.

[BobL]

And how did you slide the shaft back in were any bolts loose? My boat is in the water and everything seems fine from the bilge side

[Rumlater]

What is your transmission a KM2-A cone clutch model? I Have my KM3-A on the bench right now awaiting cone clutch and seals for it. It is not hard to disassemble and is straight forward, no springs to fly out when it comes apart. The shifter that pushes the cone clutch into gear might have become damaged. If you can get a hold of a manual you will see it is not difficult at all.

[BobL]

My manual says it's a KM2C constant mesh with servo cone clutch. Do you have to take the whole transmission out to fix it?

[Rumlater]

BobL, what do you think made the seals leak? What seal? Input or output shaft? To remove the transmission there are 8 - 12 mm bolts to remove, plus the shift linkage.
I did not have enough room to slide it off the spline due to the coupling, had to take out the engine mounting bolts, remove engine throttle cable, fuel shutoff cable and exhaust hose to move engine ahead 1".

[Rumlater]

Not sure how you would remove the oil seal with out pulling apart. It is step # 10 after removing all the gears, the nut on the input and output shafts are left hand threads. I would not like to try and change the seal on the output shaft while it was still in my boat, it was tight enough just getting the transmission out.

[tdh1849]

Bob, look up the tel# for "Complete Yacht Service" in Ft.Lauderdale. Call Mark the owner, ( USMC) and tell him Pat N with the Hunter 33.5, now lives in Tampa, told U to call.
He is the local Yanmar Dealer there and knows everything there is to know about Yanmars.

[Rumlater]

Bob, looking on internet I only find KM2-A or KM2-P model transmissions, both are cone clutches. Have a look at the plate on the back of the transmission. It will tell you better than your manual

[marlinmike]

have removed a few, unbolt coupler and slide shaft away, disconnect cable and hoses, put some blocks under tranny and unbolt and slide off and carry out. Sometimes the best thing is to bring to a tranny place, if has a lot of hours/usage a little going over is not a bad thing. Good luck!

[lesterbutch]

Originally Posted by BobL

And how did you slide the shaft back in were any bolts loose? My boat is in the water and everything seems fine from the bilge side

My shaft slide out of the coupler leaving the outboard half of the coupler attached to the drive train and a naked shaft lying in the bilge. A real good reason to keep a spare key.😊