New 6341 owner

[catskinr]

I recently bought a Zetor 6341 that was in need of some minor care and maintenance. I have most of it sorted out, but I do have a few questions:

The hydraulics work fine when cold, but they seem to get weak once the tractor warms up. I assume that the pump is the problem. Has anyone here had any luck with repairing the engine driven pump on these tractors? I am somewhat of a machinist, so grinding and lapping don't worry me, but if it's not worth trying, maybe I will just order a new pump.

My tractor has spent its whole life outside, and some of the plastic items are in poor condition. I bought new handles for the PTO and hand brake levers, but I'm having trouble getting the old ones off. Is there a trick? I'm thinking of trying a hair dryer/heat gun. Will this work?

Thanks in advance.

 

[catskinr]

I figured out how to remove the handles from the Pto and brake levers. They slide right off after removing the cover at the pivot and the latch pin. The new ones went on fairly easy once I got the button aligned properly. I haven't gotten to the hydraulic pump yet, but I'll get there soon enough.

 

[donny2stroke]

I dont think you can repair gear style pumps easily. As the teeth wear down they "squeeze" less oil through them. The problem is exacerbated as the oil heats up and becomes thinner. i am not completely familiar with the hydraulic pumps on your model but i imagine it is not a hard job to replace them

 

[catskinr]

Thanks for the reply. I haven't gotten into the hydraulic pump yet, but I'm thinking that I will at least disassemble it before making a decision to order a new one. In the past, I've had good luck with rebuilding gear pumps by replacing the wear plates or lapping the end plates. If the gears or center section are worn, then it gets a lot tougher. I'll post back here when I get it fixed and let you know what I found.

 

[catskinr]

I was able to restore my pump to probably 95% of its rated capacity. When disassembling the pump, I immediately noticed that the sealing o-rings on the wear plates or "plugs" were missing a large section. At first I thought that I would be able to simply replace the sealing rings, but after carefully measuring the gears and wear plates, I realized I would have to do a little more. From the measurements, I could tell that the wear plates were worn about .008 inches. I'm fairly sure that this wear allowed the plates to push away from the sealing rings, and the resulting leak quickly eroded the o-rings. The center housing had some wear from gear side thrust, but I decided to move forward with the repair anyway. In order to restore the gear end clearance to a more normal .001 inch, I used the surface grinder at work to remove .003" from one end of the center housing, and .004" from the opposite end of the same housing. After cleaning everything up, I reassembled the pump with new seals and o-rings and put it back on the tractor. After a 5 minute break in run, I put the hydraulics to work and was able to hear the relief valve operate for the first time since I've owned the tractor. I haven't checked the pressure yet, but I can say that the pump is much better than before! Hopefully it lasts a while...