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sterlclan
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Got both drives in and was just about done and the aux hydraulic spool got stuck on... took that out NOT EASY turns out the detent balls (I think there is supposed to be 2) I only had one and it was jammed in the cap pretty good the spring holders are screwed looks like a 2 hr trip to bobcat or at least 1hr to the hydraulic shop tomorrow .I also found an o ring stuck in the charge line where it goes into the drive pump beneath the 90 fitting at the pump I'm hoping that cures it or at least helps some ............Jeff
You just can't win!
There are 2 detent balls, one at either end of the spring. They are horrid to re-install, i ended up using a cable tie and pliers to get mine in.
The 2 ruts the balls make in the housing i just turned mine 90 degrees and it worked great. The balls now run on an un-worn part now. They lock in pretty well.
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sterlclan
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got the balls from my kids bike put that together ran it, a little better but still not great there is a check valve in the fitting that the case drain lines hook to what way does it check? that valve may be wrong it seems that the oil on the pump side of that fitting is hotter than the cooler side. I love working on something that has been cobbled by someone that doesn't know better oh well it was inexpensive when I bought it........................thanks Jeff
I'm really not sure, i know the one you are talking about, its between two hoses and about 2" long with an arrow for fluid direction. I sold my 731 that had the same setup as this so i can't even look it up in my manual....
See if you can harass your local dealer and see if they can tell you what way it should be pointed.
skidsteer.ca
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The flow must come out of the wheel motor
Ken
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sterlclan
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thanks ken............Jeff
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sterlclan
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would anyone know the number of my hydraulic pump shaft seal???? it may be sucking air through there.thanks Jeff
There is no shaft seal as such. Its all open between the 3 pumps. There are only large O rings that seal the pumps sections and one between the pump and the hydrostatic pump. Any seal shop can suply these if you take them a sample.
I would seriously doubt this is where its pulling in air, these sections are under constant pressure so you would see a leak.
Excuse my interuption but this system sure sounds similar to my JD 7775's, do you know if they're the same. thanks
I would seriously doubt they are the same but the basic setup would be close. Most manufactures use different brand parts.
I take it you are having problems with your JD machine?
Yes, I'm having problems. thanks for the response. Looking for suggestions/opinions to fix. One side was sluggish and was leaking oil so I took it apart to replace both pump cam and shaft seals. Pumps look really good on the inside. Now one side won't reverse once it's warmed up and has a load on it. When it's run on the ground (load) for 5 minutes it will reverse ok, when I can hear a chatter then the one side won't reverse. I suspect the chatter is the relief valve getting an air lock. I've gone thru the procedure in the manual for getting the air out (up on blocks, run 20 minutes reversing directions, etc..) Have read the service manual time and time again and taken the pumps apart 3 times. One thing I haven't done is the pressure tests 'cause the brakes were inoperative therefore I couldn't put a load on it when it's up on blocks. I have a hunch it's getting excessive pressure in the pump cavity, this would cause the seals to blow. I replaced the 4 pump reliefs with new ones. Thought I'd pull that pump again and really look at the valve head for a crack - maybe take it to the machine shop for magnaflux. Considering buying a new pump, they're not that expensive (less than $1100) but figured I'd better fix the brakes and run the tests first - could be the motor. thanks again
I'm un-sure about this model but some require a special process to remove the air from the system. Some will do it on their own but some will not. As you have the manual it seems you have all the rite info for bleeding the system.....
I take it you have only worked on the pump and not the motors? the only reason i ask is that some motors use a valve plate that must be installed correctly or you can have odd problems with direction.
Low charge pressure would cause problems with both sides not just one. The chattering, can you feel it through the sticks? It may be the shoes on the pistons in the rotating group smacking into the yoke on the pump, again could be an air issue.......
It really wouldn't ne a bad idea to throw a gauge on the charge pressure line and see what its doing. Hopefully someone else may have an idea.
One other thing, have you checked for hidden filters? and changed the ones you can see too? never know.
Haven't gotten into the motor for that side yet, thought I'd think and check around a bit and do some tests before I opened that up yet. I see in the manual where the motor does have a valve plate. Wouldn't think it would be low charge pressure as it has blown the seals but I'm going to check that. I suspect a cracked valve body thats causing the pump to leak from high side to the low. Checked the manual for filters, changed the one=and=only (pricey thing!). Will send in results when I find problem - I take it as a challenge. thanks
Have you tested the pressures?
If it has poped the seals, i would suspect a blocked filter in your return line. I would seriously doubt you would have a crack in the valve body and if it was, i can't see it causing high pressure in your charge circuit as the relief valve for the charge pressure would allow that high pressure out. Some have a hidden filter in the return line(s).
I too wouldn't touch the motor straight away.