California
Super Star Member
- Joined
- Jan 22, 2004
- Messages
- 14,983
- Location
- An hour north of San Francisco
- Tractor
- Yanmar YM240 Yanmar YM186D
At least on the smaller/earlier Yanmars, the PTO is driven by direct shafts and gears same as a manual transmission, while the Powershift input is (logically) driven off another shaft after the transmission input independent of the PTO. This is why you can let the clutch out to start a tiller etc spinning, then later shift the little Powershift lever from N to 1 to get the tractor moving. Since they are independent, a working PTO will tell you the conventional, automotive clutch up on the flywheel is ok, but a good PTO doesn't imply anything about the Powershift.
If nobody anywhere has experience with a Yanmar Powershift then I think the next alternative is to find a mechanic - probably an old one - experienced in a bench teardown of Japanese automatic transmissions. Long ago, like over 50 years ago, I tore down an Oldsmoble Hydramatic following instructions from a Motor's manual and replaced the clutch elements like what is in this Powershift. Its not magic. What you need here is a mechanic experienced in tracing the hydraulic circuits where a blockage is most likely the problem. And worst case, someone who recognizes that those same clutches are also used in some Japanese car or motorcycle. If so then replacements are available, or maybe similar ones could be cut down to fit. This isn't an impossible problem; you just haven't found the right mechanic.
If nobody anywhere has experience with a Yanmar Powershift then I think the next alternative is to find a mechanic - probably an old one - experienced in a bench teardown of Japanese automatic transmissions. Long ago, like over 50 years ago, I tore down an Oldsmoble Hydramatic following instructions from a Motor's manual and replaced the clutch elements like what is in this Powershift. Its not magic. What you need here is a mechanic experienced in tracing the hydraulic circuits where a blockage is most likely the problem. And worst case, someone who recognizes that those same clutches are also used in some Japanese car or motorcycle. If so then replacements are available, or maybe similar ones could be cut down to fit. This isn't an impossible problem; you just haven't found the right mechanic.
