robilmichael
Member
Hi, a while back I posted asking for suggestions on replacement of the MF135 hydraulic piston rings as the lift would leak down rather rapidly over time. Thanks to all for the helpful suggestions.
Attached above are pics of the process to assist others in the tedious process. I removed the double hydraulic spool and cover bolts, drained some oil out, removed the side plate and used a thin wire to attach to the roller pin to avoid it falling off or slipping out of my fingers as I removed it. I can see that if it falls off and falls to the bottom of the section it would be a major pain to get it out.
I used the same type of wire to hold down the "dashpot plunger" but that was unnecessary as I did not turn over the cover and it will fall out only if you turn the cover over.
I used a pulley system to lift the cover off straight. The old piston was removed by compressed air into the standpipe hole. It was 3 1/8" in size. The bore was in perfect shape. The old piston had three rings, and the new type 3 1/8" piston has only one groove for one rubber ring and a sealing teflon ring that sits on top of the rubber ring. I boiled the teflon ring for 2 minutes to soften it, and then used two screwdrivers and both feet to hold the piston and sealing ring partially on the piston and then to pry it on the piston on top of the rubber ring.
A piston compressor was used compress the ring/piston and drive it into the piston bore using a strong wooden dowel. The bore already had a very slight beveled edge to it.
I used two bolts with the head ground off to screw into the housing to align the cover as it was set back on. This is imperative as I can see how you would break or bend something if the cover is not set back on completely straight and true.
I removed the temporary alignment bolts, bolted it on, and then started it. To my surprise the lift worked great! I then drove it a bit to check for leaks, and warm it up. I put a very heavy 6" mower on it and lifted it and let it sit overnight to see if there was any leakage. The next day, it had not dropped at all.
After a few weeks now I am happy to report that the lift is now very responsive, accurate and has absolutely no leak down at all.
Thanks to all for the suggestions and good luck to all who need to do this job!
Attached above are pics of the process to assist others in the tedious process. I removed the double hydraulic spool and cover bolts, drained some oil out, removed the side plate and used a thin wire to attach to the roller pin to avoid it falling off or slipping out of my fingers as I removed it. I can see that if it falls off and falls to the bottom of the section it would be a major pain to get it out.
I used the same type of wire to hold down the "dashpot plunger" but that was unnecessary as I did not turn over the cover and it will fall out only if you turn the cover over.
I used a pulley system to lift the cover off straight. The old piston was removed by compressed air into the standpipe hole. It was 3 1/8" in size. The bore was in perfect shape. The old piston had three rings, and the new type 3 1/8" piston has only one groove for one rubber ring and a sealing teflon ring that sits on top of the rubber ring. I boiled the teflon ring for 2 minutes to soften it, and then used two screwdrivers and both feet to hold the piston and sealing ring partially on the piston and then to pry it on the piston on top of the rubber ring.
A piston compressor was used compress the ring/piston and drive it into the piston bore using a strong wooden dowel. The bore already had a very slight beveled edge to it.
I used two bolts with the head ground off to screw into the housing to align the cover as it was set back on. This is imperative as I can see how you would break or bend something if the cover is not set back on completely straight and true.
I removed the temporary alignment bolts, bolted it on, and then started it. To my surprise the lift worked great! I then drove it a bit to check for leaks, and warm it up. I put a very heavy 6" mower on it and lifted it and let it sit overnight to see if there was any leakage. The next day, it had not dropped at all.
After a few weeks now I am happy to report that the lift is now very responsive, accurate and has absolutely no leak down at all.
Thanks to all for the suggestions and good luck to all who need to do this job!