Yanmar 336D front loader hydraulic issue

[davidvelky]

I recent purchased this tractor that had been in a field for years. went through and changed all fluids, filters, screen and cleaned out the insides. The front loader is slow and shakes lifting, going down is fine. Same happens when I curl up. Curl down is fine. Plenty of fluid and all new quick connects and hoses. Any help would be appreciated.

 

[careyo63]

I had that problem and it was Swollen inside at a bend in the Hyd hose. Pinched almost off! I Cleaned the strainer basket and new fluid and made it worse! Pulled it back down and lucky I looked inside the hose. Major fbomb!! No wonder. The shop who replaced the clutch mentioned he thought it didn't sound right. Shortened that section right above the Wagner strainer. 2" section you can barely see on the L. of the Pic.. Super smooth now.

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[davidvelky]

thank you. Ill look for this and pull it to see.

 

[kenmac]

thank you. Ill look for this and pull it to see.

could also be rust, etc, in your loader valve if it sit outside for years

 

[winston1]

Make sure your pump suction line is not sucking air someplace.

 

[oldnslo]

Sounds like the pump is cavitating or sucking air like winston stated. Could be collapsed line, loose fitting, etc.

 

[etpm]

A friend of mine has a Struck dozer and the blade would move in one direction just fine but in the other would move one side faster than the other. So the blade would move in a crooked manner. One cylinder was moving faster than it's opposite cylinder. I told my son, who was working on the machine, that I thought there was a restriction in a hydraulic line. This was indeed the case, one line was constricted at the crimp. Looking in the end of the line it was easy to see that where the hose was crimped into the fitting on the end of the hose there was a constriction. Removing the constriction fixed the problem.
Eric

 

[davidvelky]

could also be rust, etc, in your loader valve if it sit outside for years

Could you tell me where the loader valve is located on the 336?

 

[rScotty]

I'd look at the suction line from the sump to the pump. Hoses and connection, including the line to and from the screw on filter. Sounds like that is where it is. Even if a suction hose looks good, old ones will leak air and cavitate the pump.

The "loader valve" usually means the Front End Loader Control Valve - the one you work with your fingers to move the bucket & arms. It is not rebuildable, but it also has a relief valve built in - the longer can - and there is a spring and ball inside that relief valve that can rust.

rScotty

 

[careyo63]

Reply #2. Suction from the from the Hyd. Res. is the metal Strainer that says Wagner which is a filter also. Filter will be on the suction so it will give you an idea how they plumbed it. There is a smaller other line out on the other side which is the Pressure line to your Control valve. All hyd. pumps work pretty much the same depending which or how you access the pump. This one is driven from the crank shaft. I have a 3pt. lift pump also which is setup pretty much the same as your 336. My Loader is self contained and only a few bolts and a Drive shaft to the pump to remove it all Intact. I would be looking at the hoses were they may have been cut, Adapter connections were they cut the lines for leaks or T's, Elbows Pinched off hose even clogged and Chk. the clamps are all tight. If it was the Loader valve nothing would work and one thing is not operating then look at the Loader valves and the hose that connects it.

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