Yard Pro Hydrostatic Tracter

My old Yard Pro Tractor Model 421171 still runs and mows great but top speed has been lost. It seems to have lost 40% to 50% of it"s original speed. A friend suggested checking the fluid level in the Transaxle Hydro Gear Model #310-0500. I have all the manuals including the exploded views and part numbers but I can not find anything that indicates a place to check or fill the transmission fluid. Any help will be appreciated

Checking your fluid level is essentially pointless.

If the hydro was really low on fluid, then you would not be able to move the tractor. Simple as that.

I agree that you do need to locate the fill plug but you also need to locate the drain plug IF.....your hydro actually has one. If it does, then go cut your grass so that you warm up the hydro as much as possible. Then slide a drain pan under it and remove both plugs. Let it sit for at least an hour to get out as much of the old oil as possible.

Install the drain plug and then refill the hydro with the CORRECT amount of CORRECT fluid. Check with Hydro-Gear's website or a Hydro-Gear dealer on both issues so that you know to a certainty that you are doing it right.

It might call for 10'w30 or 20W50 or even one of the ATF fluids. While oil does not really wear out, it does change viscosity thanks to heat, time and shearing. Fresh oil MAY make a huge difference. If it doesn't, then the hydro's pump and drive motor are worn to the point that speed is suffering. Either a new hydro or a rebuilding will cure that problem.

If there is no drain plug at all on your hydro, then remove the complete axle and drain the hydro using the fill plug. PITA... I know but ......... the longer you leave that old oil in there, the worse your hydro will get. Clean oil will extend the life of your hydro.

Check the mechanical linkage in the hydro control a loose connection or wear will keep the hyro from going all the way to the maximum speed.

Thanks, I will try your suggestion

Sounds like you are correct about the PITA thing, also removing the complete axle is way beyound my mechanical expertice. It's beginning to sound like I need to find a hydro gear dealer or service center. It may not be worth the effort, this tractor was purchased from a friend 15 years ago after he used it for more than 10 years.

I have a Chraftsman with a Hydro-Gear in it. I called Hydro-Gear because I wanted to change oil in it. They told me no check plug or drain plug. I was told it was a sealed unit and don't mess with it unless it picks up a leak or a problem. I will give You there address & phone . Maybe you can get more out of them than I did. Hydro-Gear Corporation 1411 S. Hamilton ST. Sullivan, IL. 61951 217-728-2581.

Thanks for the info, I had a feeling about not messing with it. I've decided to find a repair service and let them handle any work it may need. Thanks for the address and phone number.

I would go with Traditional Farmer's suggestion first, wear on linkage over the years can make a big difference. I kinda lost track over the last few years, but I bought a Craftsman 21hp hydro last year, (or as they call it, automatic) and it is a sealed system.

I agree with the suggestion to check the linkage first to make sure that you are getting full travel on the hydro's control arm.

Keep in mind that Hydro-Gear makes many types of hydrostatic units that cover all the various price-points of lawn and garden tractors. The lower end hydro's are often the "sealed" units that were mentioned by another member in this thread.

Of course, you can expect the Hydro-Gear representative to tell you what he did. Who's to say as to how much he knows about hydro's? Just because he works there; that does not automatically make him an engineer or an expert. If changing out the oil was not a good thing, then why does Hydro Gear install drain and fill plugs, as well as filters, on their better units? If you don't think that oil deteriorates from use, then there are sites such as Bob is the oil guy that can explain in great detail why oil in hydro's needs to be changed after a certain amount of hours of use. This is not about "messing" with your hydro. To the contrary, it's about doing the one thing that not only extends the life of a hydro but also keeps the hydro performing as it was designed to perform.

From the moment that Yard Pro was put into use, the hydro began to wear and that wear began to contaminate the oil with metal particulate. That contamination stays in suspension in the oil and makes the oil more and more abrasive and that accelerates the wear.

Filters are added to hydro's to remove these contaminates down to a certain particle size but a filter will not clean the oil 100 percent. Only changing the oil can do that. In addition, hydrostatic drives require oil that has a stable viscosity. If your tractor shows good ground speed when first started up but that ground speed drops off noticeably once the tractor fully warms up, then that's a signal for an oil change. Your tractor.... your decision.

Thanks Tom, I've decided to find a service center and let the pros take care of the problem. The linkage seems to be fine. Tearing into a sealed system is way more than I feel comfortable doing. Any help with finding a service center in southwest Louisiana would be appreciated.

What you're going to find out about the "sealed" transmission is that very few parts are available on the inside, and the ones you can get will be more expensive than replacing the transmission, especially if you're paying someone to do it.

The other thing, it likely doesn't have a drain plug, kind of the way with a lot of the push mowers these days. The FILL plug is also the drain plug. It will be easier to remove the transmission and flip it over than rotate the whole tractor upsidedown to drain the oil and refill.