Multiple hydraulic problems JD 4300 HST

[roquefortnight]

Hi all, I'm a new member and hope someone can help me. I used tractorbynet extensively when I was shopping for my tractor several years ago, and it was a huge help. I ended up getting a John Deere 4300 HST and have been generally happy with it. This was before JD went to the electronic transmission controls.

My hydraulics are quite messed up at the moment. Steering, front end loader, three point hitch and transmission are all not working properly. A little history first: a couple years ago, I snapped my steering cylinder (next to the front axle) by running into a stump. Replaced the cylinder in the field and changed the hydraulic fluid. There were some metal particles in the pickup screen, which I have saved: about a level half-teaspoonful, magnetic, the largest pieces are about a half-inch long, and they appear like little warped pieces of sheet metal. They haven't shown any propensity to rust.

After this, the steering had a tendency to wander, and I'd have to keep turning the steering wheel to go in a straight line, but the rest of the tractor's functions worked fine, and I've since used it for some fairly heavy work for the machine's size, mostly winching/skidding logs with a Tajfun winch and snow removal with a rear PTO blower. The JD has about 650 hours on it, though a fair amount of that time is idling. I'm not sure exactly how long has passed since I replaced the steering cylinder, but just guessing I'll say 100 hours.

A couple days ago, after a heavy snow, I noticed the loader was slow and "notchy" in raising, and it took a few moments after moving the joystick before the loader would respond. The three point hitch then started acting a little slow. Finally, I had a bucket (60") full of snow and found I couldn't raise it at all.

Today, trying to figure out what is wrong, I started the tractor and it would not respond to the hydraulic pedals. No strain or load on the engine, pressing the pedal did nothing. The operator-sensor switch works, and will kill the engine if I try to move the machine by pushing on the pedals without sitting in the seat. After several attempts, I was able to raise the bucket just enough to dump the snow, and I managed to back up the tractor about 20 feet to a more accessible spot, although there was quite a bit of groaning going on (in the transmission, I guess).

Right now I'm trying to figure out what to do. It will be dark before long, and I don't have an indoor space to work on the tractor (and there's a lot of snow outside). I'm trying to decide which is the wisest course: drive to the dealer and get new fluid, filters, etc., and hope that the problem is a clogged pickup screen, or something, or should I have someone from the dealership come out ($). To my uneducated eye, it looks like there are two pumps near the front of the engine I'm guessing one is for the steering and one for the joystick (or whatever it's called), but I guess there must be another pump for the transmission somewhere.

If anybody can offer some advice I would surely appreciate it. We depend on this machine, and there's likely a bit of winter weather yet to come.

I don't know what the forum etiquette is, or if it's ok to duplicate this post in the Hydraulics section of tractorbynet.

 

[dfkrug]

First, can I assume you did the obvious and checked to see if your
fluid is full and not cloudy?

Second, when you say you had metal particles in the pickup screen, did
you remove the suction filter from the bottom of the gearcase? A lot
of debris/gunk on it can cause these problems.

Your HST charge pump is one of the two hyd pumps on the front of the
tractor...it shares duty with the PS. Since all of your hydraulics are
not running correctly, my suspicion is that you have caused a severe
restriction in the system (dented hyd hardline underneath, clogged filter,
etc) or the common shaft between your two front pumps has partially
sheared.

 

[mfreund]

I would change the fluid and filters and clean the suction screen. I would suspect there is some debris in it. If the metal from b-4 did not rust it must be aluminum :-(

 

[roquefortnight]

Thanks, the fluid isn't cloudy and doesn't seem to have any debris in it. The suction screen (it's been a while so my memory is not fresh, but a figure it was about 8" or 10" long and made with a sort of corrugated nylon fabric) is where I found the shavings when I replaced that steering cylinder a couple years ago. I also replaced the spin-on tranny filter. Is there another pickup screen that I missed or don't remember? I don't see any evidence of a dented steel line.

 

[RoyJackson]

At this point, I suggest doing two things:
Flushing out the hydraulic system altogether. Since you wrote about debris...some of that debris may be restricting the hydraulic flow (at a check valve, perhaps).
The other thing is to check all fittings for tightness. You may be pulling air into the system. I doubt it's a cracked line...if that was the case you should see hydraulic fluid spraying or misting out (and under or on your tractor).

 

[roquefortnight]

Thanks again. By flushing the system, do you mean with an external hydraulic pump? Is this something that can be rented, or am I better off having the dealer do it? It did occur to me that getting the front end loader off might be difficult if I can't get the hydraulic cylinder to fully retract. Getting the snowblower off the rear will probably be a pain too, if I can't back the tractor up, but at least it can be muscled around if there's no alternative.

 

[RoyJackson]

Thanks again. By flushing the system, do you mean with an external hydraulic pump? Is this something that can be rented, or am I better off having the dealer do it? It did occur to me that getting the front end loader off might be difficult if I can't get the hydraulic cylinder to fully retract. Getting the snowblower off the rear will probably be a pain too, if I can't back the tractor up, but at least it can be muscled around if there's no alternative.

You could do it at home, but the dealer would be more convenient (except for the $$$) especially during these cold winter months. If you do send it to the dealer, just leave the loader on. They can use another tractor's hydraulics to remove it.
But it would be better if the loader was off. It might be easier to flush the loader and tractor seperately.
The dealer will be better equiped to bleed any air too (but that's just a matter of cracking a line and bleeding air).
If you do this at home, it'll be advisable to have a hydraulic schematic. Specifically look for check valves (heck, you might even have a bad check valve restricting the hydraulic flow). Also, if you do use another tractor to remove the loader, figure out how to filter the hoses between their tractor and yours. It wouldn't be neighborly to contaminate his hydraulic system.

 

[Egon]

If the tractor is close to power I'd suggest putting a tarp over it and an electric heater so you can work in semi comfort.

Then drain the HST fluid and pull the screen and filter to see whats there. After that make some decisions.

The transmission has two Non adjustable PRV's just to the right of the filter. The manual will call for a 10,000 psi gauge if you check pressures. There are also plugs for a pressure gauge located there.

The loader joy stick has an adjustable PRV under the right fender.

Do you have a manual?

There are three pumps, one up on the engine for power steering, and two together behind the filter case. One of these is a charge pump and the other is the main pump.



There is a thread from just several days ago here on a JD 4200 on which the loader would not work.
http://www.tractorbynet.com/forums/hydraulics/164131-john-deere-4200-loader-slow-4.html#post1892726

 

[jd110]

I would check te rubber "manifold" on the hydraulic pump. The suction line hooks up to this manifold. I have seen some of these develop a crack that will suck air. It is high enough that oil won't run out when not running. It is #2 in the diagram. Also check hose #8 for tight clamps.

 

[IH3444]

How warm is it where the tractor is at? Is it possible that there could be condensation freezing in the lines, FEL control valve?