Mower Gear Box - grease or SAE 80?

[gorilla]

My RC72 mower deck gear box has a leak at the PTO shaft. I have read on this forum a couple different options to fix:
1- replace the oil seals
2- use grease instead of gear oil

Since it's an older mower deck I am inclined to go with the grease as the tolerances might be off/worn with the age of the mower. But I do not want to ruin the gear box either.

Has anyone used the grease option and had to replace the gear box because it failed?

 

[CountryBumkin]

I wouldn't trust grease to work unless you were to pull the box apart and hand pack the bearings - and if you're going to pull it apart, might as well replace the seals and use gear oil. IMO.

 

[Southernfarm]

You could consider John Deere corn head grease. See it in action on this gearbox https://www.youtube.com/watch?v=UEwk_sYP6A8

 

[cerlawson]

I've had that sort of problem with roto-tiller and adopted the rule to fill the gear box with the heavy oil before each use of an hour or less. It still is working fine.

 

[Diydave]

Most of the rotary cutters I have had spring a leak, its been the lower seal, under the deck. I usually drill in a fitting and just fill the lower bearing area with grease, then about 7-8 pumps, when I start them up, in the spring. I still add oil, if it needs it, usually not very much. Never had one fail, yet.

With the PTO seal, you might want to check the bearing pre-load, per your manual. If the backlash on the pinion gear ain't right, shaft wobble can eat up a seal, quick...

 

[CurtisC]

I rebuilt a rotary tiller that I couldn't get the main shaft seal for. One of the reasons it had been abandoned was the drive chain and sprockets had been trashed probably from lack of oil then someone tried to pack it with grease. After rebuild I filled gear box and side chain reservoir with 140WT gear oil. Its a little hard to find but NAPA carries some. Leak slowed way down at main shaft seal to where I top it off once a season.