Yardman (MTD) Hydrostat Fluid

[psimmer]

I picked up a 1994 Yardman 20hp 50 inch hydrostat mower. Runs great, but has a leak somewhere under the rear end. I haven’t investigated what the leak is yet. The manual says it’s filled at factory and to go to the dealer if there are any issues. It looks like seat and metal under it have to come off to even see top of hydro. Any idea how to check fluid and what to use in it?

 

[TomIn]

I picked up a 1994 Yardman 20hp 50 inch hydrostat mower. Runs great, but has a leak somewhere under the rear end. I haven’t investigated what the leak is yet. The manual says it’s filled at factory and to go to the dealer if there are any issues. It looks like seat and metal under it have to come off to even see top of hydro. Any idea how to check fluid and what to use in it?

I know nothing about thirty-year-old Yardman mowers but will toss in my 2 cents worth since nobody else has replied. Some internet searches indicated that the Yardman mowers of that era used Hydro-Gear transmissions that used 20w50 oil. Various forums had questions about these transmissions. The most meaningful replies suggested finding the model number of the transmission then downloading a service manual from the Hydro-Gear website:

Residential Drivetrain System Manufacturer - Hydro-Gear

Safe and reliable residential drive systems that last throughout the life of the most demanding residential applications.

www.hydro-gear.com

Under their Product Support tab you should be able to find out how to identify the model number of your transmission and download the appropriate service-repair manual.

 

[Duner Wi]

I picked up a 1994 Yardman 20hp 50 inch hydrostat mower. Runs great, but has a leak somewhere under the rear end. I haven’t investigated what the leak is yet. The manual says it’s filled at factory and to go to the dealer if there are any issues. It looks like seat and metal under it have to come off to even see top of hydro. Any idea how to check fluid and what to use in it?

If it's like my Yardman you remove right rear wheel and remove level check plug with 1/4 "Allen wrench after you level tractor all directions. Plug is about level to the rear of brake. Factory fill was 10/30 per MTD owners manual. Drain oil by removing oil filter. My Hydrogear has numbers attached to right hand side. I refilled mine with Royal Purple 20W50 which works well. I travel about 10 miles
with 42 inch offset tow behind finish mower in addition to 46 inch deck mower . Working from memory I think my Hydrogear is # 718-0241.

 

[psimmer]

Thanks for the replies. I did find a tag on mine, it is a Hydro Gear 718-0241 same as yours. I haven't removed the wheel to find the level check plug yet. I think I will get a filter and oil before I do that. And I will go to to the Hydro Gear site and try to obtain a service manual. Again, thanks for the replies.

 

[TomIn]

Thanks for the replies. I did find a tag on mine, it is a Hydro Gear 718-0241 same as yours. I haven't removed the wheel to find the level check plug yet. I think I will get a filter and oil before I do that. And I will go to to the Hydro Gear site and try to obtain a service manual. Again, thanks for the replies.

Now that I know the model of the transmission, I did another search and found

https://www.external_link.com/threads/hydro-gear-transmission-p-n-718-0241-question.1392968/

That site had a link to a parts diagram that showed most parts are no longer available but did provide part numbers for filters which will fit.

 

[Duner Wi]

Fill plug location. Mine was quite tight.

 

[psimmer]

Excellent picture. Thanks