YM336D Hydraulic Problems

   / YM336D Hydraulic Problems #1  


New member
Mar 11, 2023
Yanmar 336D
I have finally had a chance to put the new tractor to work. There are a couple issues that I will address in separate threads.
First, I have a brush mower. It is very difficult to keep it at a proper height. Very slight movements of the 3 point lever puts the mower on the ground or all the way up.
After using the tractor for a while I noticed the front end loader started raising slower and then even slower. One morning after a 15 minute warm up it wouldn't lift at all, or the 3 point. A couple hours later I tried again and it would lift, and the 3 point also. It takes about a minute from ground to fully extended. The loader and the 3 point both lower like they should and the control lever for the drop speed of the 3 point works properly.
I also noticed there is a slight gasket leak from the lift arm housing and the lower case.
When we bought it the loader was quick to raise and lower as would be expected
We purchased this reconditioned. New paint, tires, fluids, filters etc. Some other parts are new. Mostly cosmetic, but it is an older tractor.
There is plenty hydraulic fluid in it and it looks clean. The hydraulic filter is 1452 which comes up as a Napa oil filter, but I don't see the Napa logo. I'm not sure if this is the correct filter for the application. I plan on ordering a new filter from Hoye, and understand there is an internal screen that might need to be cleaned. Other than that I am at a loss on what could be the problem
   / YM336D Hydraulic Problems #2  
Doesn't hurt to clean the screen, but it may be that the O ring seals in the hydraulic lift need to be replaced. I think there's a particular O ring on the valve that controls the speed of the lift/drop. It sounds like it isn't regulating the flow of hydraulic fluid like it should and that's why slight movements of the three point lever may make the 3pt react faster than it should. This assumes that the valve hasn't been opened up more than it should be.
   / YM336D Hydraulic Problems #3  
You will get the correct micron filter if you order from Hoye. If you have not cleaned the suction screen you need too.

Your suction strainer is behind a 3 bolt flange right under the pto shaft.
   / YM336D Hydraulic Problems
  • Thread Starter
The parts manual shows an o ring for the flange seal. So you just remove the flange and pull out the screen? Is there anything else to consider while the fluid is drained?
   / YM336D Hydraulic Problems #5  
You probably noticed the parts manual also shows an inner strainer (#50) that feeds the powershift pump. I am not sure just how much access one has to that.
   / YM336D Hydraulic Problems #6  
My Org.YM 2000. did the same No loader!! 3Pt.. Screen was clogged and it looked like Crisco Grease an inch or more deep on the bottom of the pan. Super Nasty!!! And Stunk Like???? Had to scape it out! Everthing lifted and lowered much better but I had a problem with the 3Pt. staying up. Ended up the washer on the Lift handle was gone. I ordered the New Screen It was so bad. Fredricks!! The old Filter Screen had a cooper bead on it were they welded/replaced the screen on it. No doubt about it and was dented up! Tightened the Tention spring to the 3pt. were it had play in the linkage and haven't had a problem since 08......... 1000 Tach. Hrs. since coming up and I'm going to let it go. Noway could it be in that bad of shape Screen/Fluid.


  • 002 (3) (600 x 450).jpg
    002 (3) (600 x 450).jpg
    200.8 KB · Views: 178
   / YM336D Hydraulic Problems
  • Thread Starter
You probably noticed the parts manual also shows an inner strainer (#50) that feeds the powershift pump. I am not sure just how much access one has to that.
Looking again, I do see that but don't know where it is. Is it internal or external?
   / YM336D Hydraulic Problems #9  
Internal, but no idea how you access it.