Lift Bucket Problem

[Mike Eagle]

I have a 1964 MF 165 with a MF 235 front end loader. The bucket seems to have a mind of its own. When I try to scoop it either digs in or rides up over the pile. When dragging with the loader the bucket releases and does not stay in position when the tractor moves. I have replaced all seals and O-rings in the bucket cylinders. The Cross, 4-way control valves for the lift and bucket have been inspected and no problem areas found. The lift valve has a float position. All equipment is original. No leaks in hydraulics. It has a separate fluid pump driven by the engine. Anyone have any suggestions as to how I might solve this problem. Thanks.

 

[J_J]

I believe I would put a pressure gage in the system and use the data to analysis the problem.

 

[kennyd]

What you are describing sounds like a spool valve problem to me, not sure how you "inspected" it, but if it's 46 years old...

 

[Mike Eagle]

Good idea JJ. Any suggestions where to put these gages? Thanks

 

[J_J]

First check the pressure at the input to the valve, and then check the pressure at the cylinders. Activate a lever until it goes into relief, and that is your tractor pressure.

 

[Mike Eagle]

Thanks JJ. I'll give it a try this weekend.

 

[Mike Eagle]

Thanks Kennyd. When I inspected the valve I looked for wear, scratch marks, broken or deformed O-rings or other deformaties. Yes, the valve is 47 years old but the material used was cast iron. The two valves were machined out of one block of cast iron and the valve weights a "ton". The spools looked like the day they were machined, shinned like they were chrome, with no scratches, dings or wear marks. O-rings were stiff but not brittle and in this valve they are only used to hold the hyd oil inside the unit. Guess that is why the old tractors are so popular - they were built solid to take abuse and keep on running.

 

[wdchyd]

Mike,

unless your valve is machined for work port reliefs (which I don't believe Cross valves are), then I would check your cyl seals again...I know you don't want to here that but I would suspect them....do they hold a load when just lifting?? Do you remember if the seals on the piston head were orings and backups or urethane seals or 2 piece piston seals??there are ways to test them but you'd have to prove them out separately (we use a test machine with meter-out flow valves)...

Other than that the control valve could be cracked internally between porting in housing(rarely see that tho)....

 

[Mike Eagle]

Thanks for your reply wdchyd. To answer a couple of your questions. The control valve does have two work port relief valves. The seats on these valves show no signs of wear. No way to check the springs that hold the valves in position. The seals in the cylinders are O rings with backups. The cylinders have been checked in a cylinder repair shop with no apparent problems. There is no drift on either the lift or bucket cylinders after you get a load into the bucket. It is just darn difficult to get the load into the bucket. An internal crack in the control valve is something no one has mentioned before. I am in the process of putting some gages in the system to help with this problem. This is proving to be not as easy as I first thought. Thanks again.

 

[J_J]

The hyd gage should be installed on a tee at the input to the FEL valve. Then it will indicate the pressure for any hydraulics utilization. I would suspect the valve is sticking in the float mode. Can you raise the front wheels off the ground using the bucket, or does the loader arms leak down.