OutdoorKing Repair Forum Forums Repairs and Maintenance Questions On Ride On Mowers Questions On Ride On Mowers Frames mtd 155-hydro

Hi grumpy,once apon a time i had a mini in which uses the engine oil to lubricate the engine and gear box/diff.i also was supprised to read that the oil i used was of the correct type.the oil lubricates the diff/bearings and runs through the pump to obtain drive.it does pass through a internal filter at all times and you fill the whole hydro via the fill plug at the top so the level is 1/4 inch below the fill plug.after first fill i had the rear wheels off the ground for clearance and rotated them by hand back and forth then rotated the pump drive (where the belt goes on the pully with the fan)then started the machine for a minute and stopped.lowerd the mower on the ground and let it sit ans settle for half a day-re checked oil level and topped up,then went for a little drive forward and backwards-made a minor adjustment on the heel/toe linkage and have now used it on 5 1/4 acre blocks with excellant results.dont close this yet as i will get my daughter to do a link to the mtd hydro site and some picks...ken

Well done Ken, you've done the research so you can proceed with confidence.

The reason I did not expect the same lubricant to be pumped through the hydraulics and the axle, is that the hydraulics need ultra-clean oil, and the axle dirties it up. The filter is an imperfect solution, because it can become choked up with crud from the axle. If that happens, either you have a pressure bypass (as cars always do) so fluid will continue to flow but will no longer be filtered, or you don't have a bypass, and no more fluid flows through the hydro unit. (Car engines would not do well if oil ceased to flow through them).

I had a Mini too, Ken. Bear in mind that it only had a car engine to protect, not a hydraulic pump and actuator, which are far more sensitive to dirt. The major source of dirt is blow-by in the engine - it is even dirtier than the manual transmission. Also, the Mini had notoriously low mechanical reliability - it was the least reliable car I or my friends ever had, and many of the failures the car was noted for were major mechanical. In particular the idler gear between the crankshaft gear and the gearbox input was prone to seizing on its dirt-filled ball bearings. The car should have had a Hy-Vo chain instead of that gear train, but it would have been too expensive for a very low-priced car made in a very low-productivity, fairly-high-labour-cost country.

Hi all,sorry im late with the up-dates.put the repaired axle back in and assembled the two halves together,filled with 20w50 engine oil as recomended by the diff manafactures-let it sit over night and re checked.went for a cruise and all is good.since then have used it on 10 rather large jobs with good results.i found the correct manafacture for all mower hydro diffs on the web with full schematics-instructions-diagnostics ect so here are some pics and hopefully a link for all to use...ken http://www.hydro-gear.com/Home.aspx

Well done, Ken. That axle repair is not nearly as strong as a new axle, but it may be strong enough, and if it's not, you are now in a good position to replace it easily (though maybe not cheaply). It might be worth your while to keep an eye out for a second-hand axle as a spare, so you won't be out of action if the repaired one breaks, since you are using it commercially.

This thread is likely to be useful to others with hydro drive ride-ons. I'll now close it for the archive.