NEW YM336D PROBLEM

R Barger · Sep 27, 2014

Sure hope your right about the relief spring. I have a copied repair manual and the trouble sooting guide for the power shift is missing. When the problem first started it would come and go. Now it won't pull in the fourth range but it will in the lower ones. The manual I have does have the power shift section just no trouble shooting. thanks for the info.

grainger12002 · Sep 28, 2014

RB, Are you sure its actually staying in 4th gear ? Not trying to start anything....but... 4th gear can sometime feel like its shifted in and then just disappear when actually it has slipped (jumped) out of gear, especially if the other ranges (1,2,3) work well- the p\s is a very reliable unit, any change after clutch adjustment or inspection ? is your p\s lever on the column ?

grainger12002 · Sep 28, 2014

you can also try holding in 4th gear w p\s in low and see if it moves

R Barger · Sep 28, 2014

grainger12002 said:
you can also try holding in 4th gear w p\s in low and see if it moves

The power shift is on the transmission. It acts like not enough hydro pressure is getting to the clutch packs. In the lower ranges it feels strong. It will pull out on level ground in 4th but when it gets under a load such as a hill it's just like you shifted it into nuetral. It will stop pulling and roll backwards with the pto still turning the mower. I would like to take the unit off that holds the valve but I need to get the gasket. It may be a valve sticking or some dirt. Like I said earlier when it first started it would come and go. I think if was the clutch pack it wouldn't do that.

normde2001 · Sep 28, 2014

Yanmar Tractor Parts POWERSHIFT RELIEF VALVE SPRING

This is the spring for the FX models, but all power shift models have similar, some 1 spring inside another. You should not have to remove the valve to access it.

R Barger · Sep 28, 2014

normde2001 said:
Yanmar Tractor Parts POWERSHIFT RELIEF VALVE SPRING

This is the spring for the FX models, but all power shift models have similar, some 1 spring inside another. You should not have to remove the valve to access it.

The symptoms match my tractor exactly. The valve goes in the back of the valve body with very little room to work maybe 2 inches between it and the shifter housing. I tried it again today and it is doing the same thing in all gears. Just not as bad in the lower gears.

R Barger · Sep 29, 2014

Took the power shift valve body off today. It was a little dirty inside but no broken springs. Unless the valve was stuck I didn't see anything wrong. Broke a bolt off taking the shifter off but managed the bolt out after removing the valve body. Going to check with Hoye tomorrow to see if he has gaskets. I sure would have felt better if I had found something broken. If this don't help the only thing left is clutch packs. I don't know if I am up to that repair.

winston1 · Sep 30, 2014

Isn't there another 2nd relief valve under the valve body? I know the 226 has one and it regulates pressure to the clutch packs. Did you slide out the valve spool for examination? I will attach a parts list for the 226 knowing it is not just like yours but I believe very similiar. If you look on the drawing on figure 42 and reference numbers 37 through 41 it shows the relief valve. Actual part numbers and descriptions are on figure 41 reference numbers 37 through 41. A mistake in the manual. C:\Users\mabe1945\Documents\i_89_1_YM226D.pdf

R Barger · Sep 30, 2014

winston1 said:
Isn't there another 2nd relief valve under the valve body? I know the 226 has one and it regulates pressure to the clutch packs. Did you slide out the valve spool for examination? I will attach a parts list for the 226 knowing it is not just like yours but I believe very similiar. If you look on the drawing on figure 42 and reference numbers 37 through 41 it shows the relief valve. Actual part numbers and descriptions are on figure 41 reference numbers 37 through 41. A mistake in the manual. C:\Users\mabe1945\Documents\i_89_1_YM226D.pdf

Yes I have the valve spool out. Yes there is a second valve and I will be looking at that today. I have the repair part of the manual on the power shift with breakdown of parts. Thanks for the input. Is the first picture the valve that controls pressure to the clutch packs? that is what I feel like my problem is.

clemsonfor · Oct 1, 2014

is this the first power shift problem we have seen on here where it could possibly something inside the transmission?

I dont recall seeing anything more than low fluid, wrong fluid, or plugged screen or filter.