Yanmar 3GM30 Slips when trying to engage in forward

[william24424]

Happens more often when engine is hot. Last year I'd keep in gear through mooring field because drifting in crowded mooring field = not fun. She doesn't skip once engaged. Boat is currently on hard & I'd like problem resolved before spring. My research so far has said.

1) Shift Cable and Linkage Adjustment (Most Common) I'd hope this one is right, seems like easier/cheaper fix.
2) Transmission Oil Issues- Possibly, marina handles engine oil changes, I suppose I could check this even in off-season, maybe taste oil or apply to a salad.
3) Worn Cone Clutch -This seems like a complex repair, engine was built in 1988, I'm' not sure where to start.

Any thoughts or has anyone done this dance before & could summarize the steps. Thank you.

 

[kloudie1]

Unfortunately, troubleshooting that problem is best done in the water where a load can be put on the propeller. You've pretty well got the items to investigate except for the adjustment of the shift plate on the transmission itself.. The manual says to not mess with it so if you don't see evidence of the shift plate moving or having moved, probably best to not mess with that part. The oil required will be listed on a plate on the side of the gearbox.. usually on the starboard side. Your engine may have had either a gearbox that requires straight 30 weight engine oil or it could have a gearbox that requires ATF (automatic transmission fluid) The plate will tell you which.
There is a shop manual for the engine and transmission on this site. Click on "Owner Resources" then on "General Downloads" then scroll down to Yanmar and your engine and gearbox is there.. Good luck.

 

[marcham]

I'm not sure what you mean by "I'd keep in gear through mooring field " ?

What symptoms exactly are you experiencing? Is the driveline slipping? Skipping ? Grinding noises?

Have you disconnected the shift cable and tried to manually shift? Have you observed how the shaft behaves with someone at the controls shifting in and out of gear?
Is the behavior the same switching from neutral to reverse as neutral to forwards?

Do you have the correct type and level of oil in the transmission? (typically a 30W heavy duty engine oil, not a transmission oil). The level is supposed to be checked daily, just like engine oil.

Do you have a folding or fixed prop?

Do you keep the transmission in neutral while sailing with the engine off?

When was the cutlass bearing last replaced?

When was the alignment last checked?

The engine being warm or not should not have any bearing on the function of the transmission, as they are fully independant components. If you let the engine get to operating temperature at the dock (170 ish Farenheit), does the shifting behavior change? Or, does the shifting appear to function differently at the end of the day's sail (that is a difference sequence of events).

Cable end inspection and greasing is an annual inspection. Is there any slop or wear in the linkages ?

I'm a strong proponent of owners doing their own coolant and oil changes. Exhaust elbow and heat exchanger should be serviced annually, but are often overlooked and will cause other serious and expensive issues down the line. It's a great way to know and learn the basics of the engine, keep an eye on things and see things before they become an issue. I see Nigel Calder is now offering an online Diesel course (I have no affiliation) Marine Diesel Engines Maintenance - The Ultimate Guide Archives - BoatHowTo

Short of removing the transmission, it's been my experience that troubleshooting requires the boat to be in the water to account for the load of the propeller when shifting.