Lawn tractor starts and runs, but will not move itself anymore...

Okay, first things first. My riding mower is a PowrKraft (sold by Montgomery Ward, manufactured by MTD) 42" cut with an 18.5hp Briggs and Stratton opposed twin and an as-yet-unidentified hydrostatic transaxle (enclosed-single configuration). I might have model number and other such information written down SOMEWHERE, but the original sticker under the seat is long gone. As I was mowing with it yesterday, it began to slow down and completely stop moving from time to time. If I moved the directional lever from neutral to full forward, back and forth rapidly, a few times, it would allow me to mow again for varying distances. But as I was moving the lever back and forth, I noticed a "groaning" noise from the trans when I reached the full forward position. When it would no longer move itself at all, I moved the lever to Neutral and tried to push it without success - the wheels would only turn marginally, but the mower would not roll. I also noticed that hydraulic fluid had spewed out of the vent fitting at the end of the vent hose, and the trans was quite warm. About the only thing I have not checked before removing the trans for disassembly is whether the differential is free, but that's the plan this morning. A little study on hydrostatic transaxles leads me to believe the hydraulic motor inside the trans is hung somehow, especially if the diff turns out to be working, but I could be way off base. My questions at this point are: Anybody else experience this issue and remedy it? Any ideas who made the transaxle in this unit (I have seen a tag on the trans, but it's going to be difficult to read without removal or turning the mower upside-down!), and might parts be available? Any other things I might want to look at before I send it to the salvage yard? I would hate to let this mower go; there's actually some sentimental attachment involved, and I JUST got the engine running pretty good again. Okay, enough rambling. As always, any input is greatly appreciated. Thanks in advance - Chris

 

First update - Marginal success! The differential is free - with wheels in the air, spinning one wheel one direction causes the other wheel to spin opposite direction. The tag on the trans shows it to be a Hydro-Gear, model 718-0255A, with at least some parts support from both manufacturer and dealers/service centers. Finally, turning the input shaft to the pump with the selector lever in Neutral gives less resistance than with the lever in a motion range. Still not sure whether this points to motor/hydraulic issues or intermediate gear (?) problems, but it's a start. I may be able to get a working mower back for less than the cost of a new one. Yay! Still, any input is... you know the rest. Thanks in advance - Chris

 

Have you checked the belt? Is it in good condition and tight? Maybe it's slipping if there is any load.

 

Sounds like it has overheated and it needs to be refilled at least. Is there a lof of buildup on top of it? Is the fan still intact?

 

Thanks, cheese and Dane. Ya, the belt is sadly in need of replacement, but I'm not sure that's the primary issue since the mower would stop moving sometimes while going downhill (less load than uphill, yes?). And ya, lots of dirt/grass/schmutz buildup on top. The fan is in good shape, though. I'm pretty sure it puked a lot of its fluid, so a refill is absolutely necessary. Now, for another update - got the trans out of the tractor, prepared to disassemble and chase the problem, and just started messing with stuff. Now, I can manipulate the swash plate through the arm, turn the input shaft and watch the right axle shaft turn. So, if that's the case, and I know the differential is okay, I may be able to drain, refill, re-install, purge and mow, perhaps? I can't see that the trans is leaking anywhere, just the end of the vent hose was wet. Any special way to go about draining? The diagram on HG's website says it takes 81 ounces of 20W50; do I want synthetic, as I've read elsewhere? Again, thanks, and thanks in advance - Chris

 

Yes, use a quality synthetic.