Making Hydrostatic Trans Serviceable

[KM Richards]

I recently experienced what felt like failure of the Hydrostatic Transmissions on my Toro Timecutter MX 5475 zero turn radius mower.

After mowing for a while and getting it all warmed up, the transmission quite pulling and I could not move the mower. My first clue that it was not a permanent brake down of the transmissions was after it cooled down, it worked just fine. After doing a little reading online it became obvious I just needed to change the fluid in each transmission.

But, my mower's transmission are "non-servicable" from the factory (I suppose they want you to take it to the dealer). They do however have a port on top and the fix some are doing is taking their mower apart so they can get the transmissions out, turn then upside down to drain them so they can put in new transmission fluid. This is so stupid, I could not bring myself to consider that... I knew there had to be another option.

So, I found the video posted down below of a guy who explains how his was also giving him trouble and he simply drilled a hole in the bottom, cut some threads in the hole, and install drain plugs. A very simple and easy fix... just don't run the drill bit up into the housing as there is supposed to be some "non-servicable" filter on the other side and if punctured it could cause issues with fluid pressure potentially.

So, here's all the items I bought to install drain plugs
so I can easily service my transmissions in the future.

Century Drill & Tool 93201 1/8-27 NPT Tap and 21/64" Drill Combo Pack

Amazon.com

Stainless Steel Outer Hex Thread Socket Pipe Plug Fitting 1/8" NPT Male

Amazon.com

Permatex 80062 High Tack Gasket Sealant (put this ion the threads to make sure there are no leaks)

Amazon.com

Amsoil 20W-50 Synthetic Hydrostatic Transmission Fluid (the good stuff!)

https://www.amsoil.com/p/20w-50-synthetic-hydrostatic-transmission-fluid-ahf/?code=AHFQT-EA

Here's the video on Making A Sealed Unit Serviceable
*He talks about several safety precautions so be sure and watch the whole video.

 

[Tiger Small Engine]

Or you can extract most of oil with a pump. Remember that draining the oil does not change or clean the oil filter. Also remember that changing the oil in failing hydro transaxles does not guarantee any success short or long term.
How old is your zero turn? How many hours on meter? Are you towing with it, and do you have steep hills? What brand are transaxles and model number?

 

[KM Richards]

Draining the oil thru a hole in the bottom of the tranny while it's hot is obviously going to enable one to get more of the old oil out verses trying to put a line down in it to pump the fluid out.

Many of the commercial mowers have a spin on oil filter that can be removed to drain the oil but even on those it would be better to have a drain hole down at the bottom so all the old oil can be drained.

I bought my mower in June of 2020 and it was not equipped with an hour counter so I have no way of knowing how many hours it had on it before the original oil in the trannys became degraded. I just use it to mow my lawn and it's not used for commercial purposes.

Yeah, I'm aware that draining the oil doesn't change or clean the oil filter. On mine the filter is internal and one would have to disassemble the entire tranny do get to the filter. Changing the fluid will work just fine tho, similar to how many late model cars do not have a way to change the internal filter which is probably just a screen.

My tranny is not failing at all. If functions perfectly. The problem was the original oil was degraded and when the trannys got up to operating temp, the fluid was so bad the tranny was not functioning properly due to the bad fluid. This is common on these types of trannys.

After changing the fluid, it performed perfectly for the 1.5 hours it takes to mow my yard and the trannys were very quiet and were very responsive so there is no problem with the trannys at all now that I have drained the old oil and put in Amsoil 20W-50 Synthetic Hydrostatic Transmission Fluid

So, I'll be getting many more years of good performance out of this mower like I do my cars and trucks running full synthetic lubricants.

I'll swing by here in a few years and provide a updates about how change the tranny oil each year and how the mower is still running like new!