Branson 4220i rear lift bumping - hiccups when cold

[tjc1989]

Hey guys,
I have a Branson 4220i that has a rear lift problem thats driving me crazy, and hoping someone else has discovered the cure. My rear lift bumps or hiccups badly under load when its cold, or even cool. It seems to stop when the tractor has run for an hour or so and warmed up. The temperature swing seems to be about 55 to 65 degrees. Below that it bumps, above it doesn't.
I took it in to the dealer once, and the mechanic said he didn't find much wrong, but did replace a piston o ring on the lift piston as a precaution. He said everything else looked good. But, when I got it home, first cool morning and it was back to doing it.
I have changed fluid, cleaned the suction screen, changed hydraulic filter, and tried different adjustments to the speed valve under the seat, as well as the draft control, with no success. The current fluid is Shell Rotella Universal Hydraulic Transmission Fluid, and the filter is Branson's Kukje hydraulic filter.
I would suspect a lot of other things, except the front loader works fine, even when cold, and the rear lift bumping stops when well warmed up. I have never cleaned the pressure relief valves, nor even had the loader hoses disconnected. When fluid was changed, it was clean and clear, and there were a moderate amount of metal cuttings and particles in the suction screen.
I suspect that something changes as it warms up , but be darned if I can figure out what. If if was really cold, such as down in the teens, I might suspect fluid. When it goes to working good, without the bumping or hiccups, I can feel the lift component on top of the rear axle with my hand, and its not really hot, just luke warm.
If it did this all the way through the temperature range, from cold to hot, I might suspect piston rings on the lift piston, scored cylinder walls, lift control valve, or air in fluid, faulty fluid, or even pressure relief valve sticking, but since the front loader works OK, and the rear lift is OK once warmed up, its baffling.
Obviously in the warmer summer months I don't have a problem, when its 65 to 75 degrees when I get up in the morning.
Anyone have any ideas on this??
Thanks in advance for any input or help.

 

[firemen122]

I had a 4720 that started that around 350 hrs. Dealer said it was an o-ring bleeding by when cold and as the fluid warms the o-ring swells and fluid stops bleeding by. Made since to me, I ran it till I traded on my 6530 cab. He advised not to tear into until constant problem or failure, that way we could find culprit o-ring easy.... Good luck How many hrs on yours?

Hey guys,
I have a Branson 4220i that has a rear lift problem thats driving me crazy, and hoping someone else has discovered the cure. My rear lift bumps or hiccups badly under load when its cold, or even cool. It seems to stop when the tractor has run for an hour or so and warmed up. The temperature swing seems to be about 55 to 65 degrees. Below that it bumps, above it doesn't.
I took it in to the dealer once, and the mechanic said he didn't find much wrong, but did replace a piston o ring on the lift piston as a precaution. He said everything else looked good. But, when I got it home, first cool morning and it was back to doing it.
I have changed fluid, cleaned the suction screen, changed hydraulic filter, and tried different adjustments to the speed valve under the seat, as well as the draft control, with no success. The current fluid is Shell Rotella Universal Hydraulic Transmission Fluid, and the filter is Branson's Kukje hydraulic filter.
I would suspect a lot of other things, except the front loader works fine, even when cold, and the rear lift bumping stops when well warmed up. I have never cleaned the pressure relief valves, nor even had the loader hoses disconnected. When fluid was changed, it was clean and clear, and there were a moderate amount of metal cuttings and particles in the suction screen.
I suspect that something changes as it warms up , but be darned if I can figure out what. If if was really cold, such as down in the teens, I might suspect fluid. When it goes to working good, without the bumping or hiccups, I can feel the lift component on top of the rear axle with my hand, and its not really hot, just luke warm.
If it did this all the way through the temperature range, from cold to hot, I might suspect piston rings on the lift piston, scored cylinder walls, lift control valve, or air in fluid, faulty fluid, or even pressure relief valve sticking, but since the front loader works OK, and the rear lift is OK once warmed up, its baffling.
Obviously in the warmer summer months I don't have a problem, when its 65 to 75 degrees when I get up in the morning.
Anyone have any ideas on this??
Thanks in advance for any input or help.

 

[tjc1989]

That sounds very logical. Makes you wonder why not put a little larger diameter o ring to begin with. Maybe when it got warm it would be too tight. I wonder if there is a product that is an additive that could swell the o ring a little without disassembly? Mine has 265 hours. During research on this I have discovered that it is recommended not to travel down the road with, say a brush hog attached , with the 3 point lift in full up position. Mine has an adjustable slide stop with a wing nut tightener, that I thought prevented the lift from being in full up position, when the slide was pegged against the back stop. Perhaps that is not the case, and it must be slid a little more forward when transporting. It appears that if you transport in full up position, it causes overheating and possible damage to seals and o rings. I guess I question how, and why not in any other position. If the piston is down another inch, what difference does it make?

When I use my implements, its about a mile and a half from my house where the tractor is stored to the field, and I use the paved road to get there. It takes about 8 minutes travel time, so if it overheats and ruins the rear hydraulics in that short of a time its a sad design. I could let the rear wheel of the brush hog drag behind touching the pavement to lessen the load, but I question the stability and safety of that. With my other implements, such as my 3 point 60 gallon sprayer, box blade, or disk, that is not an option.

 

[firemen122]

Never heard about the lift use at full up like you are saying. Where did you read this? I hope my 6530 does not develop this. Let us know if ya find out any more....

 

[tjc1989]

Some were from comments on this site, some from other sites. I also called the Branson folks in Georgia, and talked to one of their techs, who also advised same thing. He was the one that said if the wing nut stop was in place, it should have been OK.

On another note, I have been thinking and researching the feasability of the o ring leaking when cold, and then swelling or expanding when warmed up and the o ring then holding and the hiccuping stopping. I have located two hydraulic fluid additives that may help this problem, as it sounds like they can swell the seals and o rings a little, plus they have anti-foam additives that the Branson tech advised to be sure and use a fluid that has anti-foam additives.

They are:
Lucas Hydraulic Oil Booster and Stop Leak
Primrose 532-T Seal Saver