Hi, I have a Poulan 300 EX, with a Hydro Gear T2 type transaxle. I recently spent much time to learn how to rebuild a hydrostatic transaxle. Although installing the center section, pump shaft, the swash plate and the two piston blocks as one unit was a huge challenge, I thought I had finally gotten it right, and turned the pump shaft to check that it turned freely. But after install I have spent at least an hour trying to purge the unit, bypass on, bypass off, and when it's bypass off sliding into forward or reverse causes a distress sound. I tried to record it but don't see how to attach the file here. Maybe you have ideas why the failure, they are welcome!
Hi, I replaced center section, the two piston blocks, both bearings with two races each, the seals. I had placed the bypass tab, yes, and when moving the direction lever in bypass, the machine makes no noise, just when the bypass is off. Upon assembly and torquedown of the center section, I moved the pump shaft to see that the pump block moved freely. I also placed the input pulley and turned the input shaft, to see that everything moved freely. I used 20-50w synthetic oil, but lacking enough oil with 2 quarts I topped it off with a 1/4 cup of a heavier Bardahl type additive. After initial purge actions, I checked the level, and saw froth on top of the oil, and the level dropped slightly, so I bought another quart of the synthetic oil and topped it up, a slight amount. I had always assumed the heavier additive would just dilute in the oil and make the oil only very slightly heavier, but am wondering if the difference is somehow preventing oil from passing the filter? The new center section came with a filter but I didn't pay it much mind; do they come with a protective surface that needs removing? Finally, the wheels do not move: in both forward and reverse lever there is maybe a slight nudge but no movement. Spinning the wheels by hand, they move freely in opposite direction, as always.
If you engage the bypass can you roll both wheels in the same direction. If not then then that part of the system is jammed, and will not allow the piston motor to turn and fully purge the system. I think your issue is on the wheel shaft/output pinion gear/ motor side of the equation.
If you engage the bypass can you roll both wheels in the same direction. If not then then that part of the system is jammed, and will not allow the piston motor to turn and fully purge the system. I think your issue is on the wheel shaft/output pinion gear/ motor side of the equation.
I checked, and the bypass doesn't allow both wheels to turn in the same direction, your comment makes complete sense, but wonder if the bypass tab could have fallen out of place, partially obstructing the motor block? One way or another I suppose a complete teardown is in order, thanks very much for your help. If the tab were the issue, would it be logical to lodge the tab in place with vaseline, say?
If there is potential for the bypass tab to fall out I would use something to make it sticky and a little bit of grease, vaseline etc won't hurt the system.
I'll follow up my post so others might benefit...many thanks to IL for his experience. I thought I had placed the center parts assemblage right, but the motor bearing slipped down and was ruined, so motor didn't move. I drained the oil, tore down, and assembled again. I used vaseline on the bypass tab to hold it in, I used a more vertical angle to assemble this time. A strip of stiff thin plastic sheet, or notebook cardboard, might help to locate the motor block without the pistons all falling out. I swore a few times; that job is best left to those who know, but where I live the qualified mechanics avoid the job. Next time, I will too :^). Tomorrow I test it, and if it works I won't have to buy a new transaxle.
@larryuno The recommended tool is a thin putty knife when inserting the motor. And you are correct most techs won't touch the hydro units. I don't know if they are just scared or are not as good as they think they are. Most will opt for complete replacement.
@larryuno The recommended tool is a thin putty knife when inserting the motor. And you are correct most techs won't touch the hydro units. I don't know if they are just scared or are not as good as they think they are. Most will opt for complete replacement.
Lots of chances for a failed repair and expensive warranty
I have done 3 or 4 and probably ended up working for $ 2/hr if I counted all the time spent cleaning .
Luckily I have a tech who is set up for them , charges 1/2 of what the parts are alone and gives 12 months warranty
Even better is they arrive fully bleed ready to fit .
I find it astounding that in the land of free enterprise no one has set up a rebuild / exchange service , there has to be good money in it .
My bloke tosses the entire unit into one of those dishwashers on steroids that I could not justify buying then splits and solvent soaks the cases so all that silicon just wipes off.
Then machines the working faces , shims as required and reassembles with new seals .
He reckoned it was about 90 minutes of actual work all up .
@bertsmobile1 Hydro-gear only gives a 90 day warranty on complete new units installed by an authorized service center. If I sell a complete unit over the counter there is no warranty. Hydro-gear encourages service centers to repair unit under warranty, but we have the option of complete unit replacement. Pays 3 hours labor for repair or 1 hour for replacement and you have to ship the complete tranny to hydro-gear factory.
Sounds reasonable
So 2 hours for doing the repair + 1 for removal & replacement.
The repairs don't take long for me but the preperation is the time eater
A drop in pump / motor down here start at $ 600 ( AU ) wholesale and the rebuilder charges far less than that if it is just a normal wear & leakage problem .
Had a couple with duff diffs
Because of Covid lock downs he currently is on 10 weeks lead time but I only do 2 or 3 a year
Amazed to see some were watching; this board has great depth! Just for news, I tested the tractor out today on the toughest hill nearby, and the machine climbed like a champ. If you come to Costa Rica, beers on me. BTW, here everything costs double what it does there, so repairs are necessary, a new rider mower here usually costs $3-4000 US, and a John Deere costs $6500.
