MF204 with 200 Loader Lift Cyl Problem

I'm having problems with lift cylinder packing blowing. Cylinders are early version self-leveling type. Two schools of thought from my buddies. First is that the hydraulic fluid is softening the packing materials (the white nylon ones soften and turn pinkish red like Dextron). I have been using Dextron for 30+ years with no problems, but recent overhaul did not last but a few hours. Second opinion I got was that the packing stack is in backwards. Replacement kit I got has stack of 8 packing rings, but no instructions which end of stack goes toward the lift pressure side. I'm looking for any help I can get from someone with real hydraulic experience.

Can provide some pictures of the blown packing on the shaft, and the new packing stack. This is first time blog for me so will need some help I you want them. I have all the books etc, and lot's of experience with this machine, but this problem has me stumped.

Hello,
As far as I can find out the 204 is an industrial model so should have double acting cylinders. If you have the correct packing/seals then there should be no problem but I would certainly confirm whether you are using the correct oil. Look very closely at the packings. If they have any sort of lip that might look like an inverted 'V' then they should be fitted so that the lip will close onto the rod when the oil pressure is behind it. If not the packings would appear to be square but might have one inside diameter slightly smaller than the other. If this is the case the smaller diameter should be fitted on the side of the oil pressure. Presumably you have a seperate dust scraper ring at the end/top of the seal housing. If you can post any photos of the seals that might help.
Let us know.
DavidP, South Wales

For sure the 204 is industrial with double acting cylinders. The dust seal, shaft and cylinder interior are all in very good shape. I have two pix. First is the blown packings still on the shaft (lift pressure would be from right, pushing to left) (drop pressure would be from left to right). Note the color of the two previously white (nylon?) packings. You can see that they appear to have been blown toward the lift pressure side. The second pix is of the current set of packings still with twist-tie holding them in correct order but fanned out a bit to see the details. Note the vee shapes that nest from one to the next. I assume as you see them in the pix that they will install with lift pressure side to the right, kind of like this: [<<<<<<]

For ref this was the left-side cylinder. Right side also got dissembled and checked, and was in perfect shape. Both cylinders see exactly same pressures since their feeds are from tee'd lines from spool valve. Why did left side blow so bad and not the right side?

the seal set pictured are old style rod seals not the piston seals,the piston most likely had cup seals with the lips facing toward the fluid side in both directions for dual action,but could have had steel rings,o-rings ,quad-rings or some of the newer materials depending on the age of the cylinder

Hello,
I'm 99% sure that you have the wrong seals. These look to be for a single acting cylinder. The fact that they have blown when the rod was retracting supports this. Can you confirm beyond doubt that you have the correct seals for this loader? Are they from the MF dealer or a hydraulic component supplier?
Pressure from the top side will force oil past the seals and not expand them to make a good seal.
DavidP

I am certain that I have the "Early Self-Leveling"version, and the design is double acting. See Pix (705-273-M91). The packing seals are correct and same as replaced on the other side of the machine that did not fail. I have to believe the parts are correct since they were obtained thru Yesterday'sTractor, and from well known After-Market mfr since MF/Agco no longer has these seal kits available. I suspect the seals should go in like this:
(lift-pressure) >>>>>>> (retract pressure)
However, you raise very good question about the packings. My example above has the lips pointing toward the lift pressure, and the failure (see pix in prior reply) shows the fluid blew past during retraction. Perhaps you are right and entire stack of packing are not correct for this double acting situation, even though advertised to be correct part number. I have not seen original parts so can't be sure. Sure wish I could talk the mfr but they seem to be insulated from us users by distributors.

I might mention that the later version (708-430-M91) is different and uses a better dynamic o-ring+backup ring design. I can't find anybody with the metal piston the o-rings ride in (1-033-686-M1). If I could get one, or the dimensions so I could make one, and buy the seals for that design I would convert what I have to the later design. The seal kits are much more readily available for it.