The other day while mowing I felt the left side steering get weak and almost lose all power. I turned off the mower and restarted it and it was better but it had a little whine like when the power steering pump needs fluid an a car. But everything I read says my transmissions are a sealed unit with no service required. Need feedback as to what can be done. Is there a way to add fluid to the unit.
I know this is an old post, but I'm sure others will continue to access it to learn some answers.
I've maintained and replaced my Hydrostatic Transmissions/Transaxles on my John Deere Z225 purchased on May 25th, 2012. It’s still going in August 2024 due to a fair amount of maintenance (replaced fuel pump, belts, starter, relays, spindles, ignition switch, etc.). Here are some things that I learned.
According to John Deere's manual: "Changing Transaxle Oil and Filter (Z425 and Z445) NOTE: Z225 model: The transaxle is a sealed component. No maintenance is required on this transaxle. If you suspect any transmission problems, please contact your authorized dealer."
This is partially right. Given the price of a transaxle or hydrostatic transmission ($1,000+ from a dealership or distributor), changing what hydrostatic transmission fluid you can, can extend the life of your transmission by removing aluminum and gear particulates that will accelerate wear. There is a threaded plug with a hex socket at the top of each transmission. They are in tight, so a conventional Allen Key likely won't get it loose. I used a longer handle 3/8 in. ratchet with a long extension that fed into a 3/8 in. Drive Hex Bit Socket.
Removing and replacing the fluid in the left transmission is easy. The right transmission, not so much. Why? Using a vacuum pump with container to suck oil out of the left transmission is straightforward as a small diameter nylon hose has a clear shot and can travel the ~4.25 inches to reach the bottom of the transmission from which you can suck out the fluid, around 1 1/4 quarts.
With the right-side transmission, there are a number of gears or other obstacles in the transmission, only allowing the hose to go down 1.5 to 2 inches. So you can only remove about 1/2 quart instead of the 1 ¼ quarts like from the left side. But it is still better to remove and replace 1/3 of the fluid on an annual basis vs. none at all. Do this after using the mower when the transmission fluid is hot and the particulates are all stirred up and still in suspension.
In sucking out the fluid, I noticed the amber colored oil had turned dark brownish gray containing worn aluminum particles in the fluid. This indicates wear and leads to additional wear. For the left side, simply refill the unit after removing the 1.25 quarts. If your transmission isn't working at all, replacing the fluid isn't going to restore it. You will need to replace the transmission.
For the right side, I added more hydrostatic transmission fluid, ran the lawnmower for several more mows around the yard and repeated the change out of the half quart. Not perfect, but better than nothing and that transmission is still going, while the other required replacement.
Cost at the dealership including picking up the mower, replacing ONE transmission, then returning the mower? Around $1450.
By ordering the part direct from Mulligan Parts Company, a distributor of Hydro Gear, the Hydrostatic transmission manufacturer, and replacing it yourself, you can save a lot of money. Note that the right and left drives have different part numbers. I don't know if links are allowed on this forum, but if not, search their website for the part that you need. Here is an example:
https://mulliganspartscompany.com/copy-of-hydro-gear-transaxle-zc-dubb-djlc-1npx/ $695 + s/h
As a DIYer with lots of tools and jacks, I did not find replacing the hydrostatic transmission all that difficult. It takes several hours, depending on your abilities. There are a few YouTube videos that will show you how.
So in short, yes, you can suck the oil out (all or partial depending on the side). You can also remove a hydrostatic transmission, flip it upside down and drain the oil through the fill hole, then replace the oil, reinstall the drive and recharge the pumps (elevate the wheels off the ground, run the engine and cycle the wheel levers for a couple of minutes). For the cost of a new transmission, and if you are handy, then sure, go ahead and do that with the transmission side that you can't suck all the fluid out easily.
Hope this helps.
I cannot promise I will check back on follow up questions, but hope this gets you started.
As an aside, if the mower won't start or is erratic with its cranking, and the battery appears to be okay, before replacing the starter, solenoid, fuse, etc., try replacing the ignition switch. I replaced all the downstream stuff only to find it was an inexpensive ignition switch. These are known to go bad. I cover the switch with an appropriately sized rubber vacuum cap after removing the ignition key after mowing.
Also be sure to install an inline fuel cutoff switch. It's easy, cheap and stops gasoline from leaking into the crankcase, diluting the oil and causing lots of white smoke when starting the engine. Diluted oil will lead to faster wear on your engine.