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Discussion Starter #1
My PYT9000 with about 90 hours on it displays what I believe is unusual slip/play in the hydro when I push down on the motion peddle, either forward or reverse. This Hydro is the Lawn tractor model and is sealed, so I can't add fluid or do anything beyond a "purge", right.

Then I may be judging the Hydro wrong, I haven't used the tractor since last fall.

When I depress the forward direction on the motion peddle (at full throttle) I firsth ear the trany whine with no motion. I continue to push the peddle, I'll guess about 25% of the full travel distance and the motion engages with a "jump". Same for reverse.

I disengaged the trany and ran the motion peddle full forward, the full reverse, if I recall correctly this will purge air from the trany. This did not change the slip/play in the engagement of motion.

Looking for suggestions, and asking is this a sign of serious trany problems?
 

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Hey Jerry I think you and I are the only ones here with PYT 9000s lol . they are discontinued at Sears, but I'm still glad I have mine. If memory serves they are essentially a Cub Cadet, so you might ask that crowd or cross post there.

I haven't fired mine up this year, but as I recall from last season I felt no such jumping. just noise...

I'm not a hydro expert by any means, so with that in mind here are some thoughts. Is the main valve (operated by the foot pedel) operating correctly? Given the sealed nature of the system low/contaminated fluid seems doubtful. Is the tranny fluid too cold/viscous perhaps? After she warms up real good and you drive it for 15 min, does it still misbehave?

any hydro experts out there?

I think I would check the linkages first; have someone operate the pedel while you watch what happens. maybe even disconnect the linkage and operate the valve by hand to see if you feel anything unusual. make sure that whatever moves on the tranny itself moves smoothly ,under the control of the various linkages.

If you are still in warranty now would be the urgent time to get Sears out to your place and get her looked at if you verify something is wrong. You dont want to fund a tranny replacement yourself :D My experience with Sears repair has been generally good - -the guys assiged to my area know what they're doing. the only time I questioned their usefulness was when I was trying to point out the design flaw of my first tractor which blew hot exhaust on the lawn and killed it. They're not engineers they are repair tecnicians so they look for things that are broken, and most are good at what they do. They should do well at determining faulty hydro behavior.
 

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Discussion Starter #3
Doug,
Thanks, my question could be answered in the experience of any Craftsman LT Hydro built since 2009, say, maybe earlier. My DYT 4000, a 2005 model didnt exhibit as much "play" but it had the hand lever, not the "gas" peddle to control ground speed.
 

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Fired mine up for the first time this season. 53 hrs on the meter. foot feed is smooth as butter. the deck spit some oil though, so I hope I don't have a leaking spindle. will have to investigate further. Did you get your driveability issues sorted?
 

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My PYT9000 with about 90 hours on it displays what I believe is unusual slip/play in the hydro when I push down on the motion peddle, either forward or reverse. This Hydro is the Lawn tractor model and is sealed, so I can't add fluid or do anything beyond a "purge", right.

Then I may be judging the Hydro wrong, I haven't used the tractor since last fall.

When I depress the forward direction on the motion peddle (at full throttle) I firsth ear the trany whine with no motion. I continue to push the peddle, I'll guess about 25% of the full travel distance and the motion engages with a "jump". Same for reverse.

I disengaged the trany and ran the motion peddle full forward, the full reverse, if I recall correctly this will purge air from the trany. This did not change the slip/play in the engagement of motion.

Looking for suggestions, and asking is this a sign of serious trany problems?
Some of the fluid has drained out of the hydro back to the sump. It shouldn't happen, but it does on some units.

Disconnecting the hydro from the engine will do no good. The hydro has to be turning and the control has to move the swashplate inside the hydro in order to eventually pump the air through the system. It takes time to purge air out, sometimes a few seconds, sometimes a few minutes.

Instructions for purging should be in the manual. I've found on my heavier hydro that just running up and down the driveway will get the air out in short order. Once it makes that "jump" keep it going at the same position for a few seconds, then the same in reverse. Full throttle should not be necessary. Try 1/2 throttle and patience. It'll clear up.
 

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Discussion Starter #6
Thanks, nice to know it is a problem (not my imagination) that can be fixed easily.

I have used the tractor for mowing sweet gum tree seed pods - that takes about 15 minutes, enough time to warm up when the air temp is over 50 degrees, as it has been.

I notice after I get the machine moving I can let off the foot peddle, then go back on and it engages smoothly. But if I stop (not sure about turning the engine off) for even a few minutes and restart the engage is again late on the travel and grabs.

The purge I've used is disengage the tranny (level out the back over the trailer hitch hole) and then with engine at full rpm to push the motion level forward, hold, then reverse, hold. I'd guess I didn't hold longer than 5 or 10 seconds. I'll try holding for a minute or so next outing, later today seems possible.
 

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Discussion Starter #7
Okay, the tranny got better with use, then the drive blet came off of the pulley and broke the cooling fan mounted to the pulley. This is the second time this has happened.

See my update on that problem at:
http://www.mytractorforum.com/showthread.php?t=237473
 
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