Changing oil in Hydro-Gear ZT-2100 transaxles, Toro SS4225

[Fredward]

Hey guys. I've been lurking on this site for a few months now, and I've been very grateful for the wealth of knowledge here. I recently bought a small farm and moved out to the boonies, which has required a crash course on small engine maintenance and operation. My most recent project is servicing the transaxles on my Toro Timecutter SS4225. This little entry level mower has been tasked with keeping about 2 acres of grass cut, around the road, house and barns. It's one oddly shaped pocket of grass after another so it takes HOURS and HOURS to mow. I've had this mower for a year and I suspect I've put 100 to 150 hours on it.

I'm halfway through the left side. I included pictures of the progress. I got the mower lifted and took the transaxle off, which was a huge pain in the butt. Drained the oil, almost exactly 1.5 quarts. Spilled a pint of oil, but fortunately on cardboard. I was able to throw some old oil rags down before any got on ground. The oil looks like it has a lot of wear metal in it. It shimmers. I put 1.5 quarts of mobile 1 15w-50 back in, and replaced the fill plug.

Now... according to the service manual, you are supposed to put the transaxle back on and run it briefly with the bypass valve engaged to purge air from the system. THEN, you are supposed to recheck the oil level, which requires taking the thing back off again. So you have to take it off and put it back on at least twice? What the crap!? What kind of masochist thought this one up?

Is there an easier way? I figure 1.5qts out, 1.5qts in, right? But at least some of the oil volatilized. The manual says, "A volume of 53.3 fl. oz. to 55.9 fl. oz. should bring the the fluid to the correct level in the transaxle." So it would seem that I have another 5.3 to 7.9 oz to go, right? But then again, I don't know how much oil is still trapped in the transaxle. And who knows how accurate my measurements were.

So what do you guys think? Should I just pour in another 5oz and hope for the best? Any advice, observations or comic relief would be greatly appreciated.

 

[ragtoplvr]

I think I would use a drill to spin it, if you can not get the chuck open wide enough then you can chuck up a 1/4 inch extension, then 1/4 to 3/8, then 3/8 to half to socket fit the nut.

Should spin fast enough to get the check balls open and purge air, low enough torque to make it safe.

 

[Fredward]

That's not a bad idea at all. Thanks, man! I'll run out to the hardware store tomorrow and get a 1/4 extension and 1/4 to 3/8. I have a 3/8 socket that fits the nut. In the mean time, I'll get the right side transaxle off.

 

[racinjason]

I always use a drill, 1/4" to 3/8" adapter. I spin the drill fast and slow, work the control lever forwards and backwards till the oil level doesn't go down anymore.

Then I fill to the top and re-install.

Make sure the vent hoses are open and not clogged with dirt.

 

[dakota99]

I don't have a hydro-gear but I used a drill on my K46 a couple of days ago after an oil change and it worked well too. It works a lot smoother now.

 

[JTK]

I'm more curious why you blacked out the ID tag on the hydro unit in the 2nd pic?

Good work on the oil change. I'm surprised there's no overflow bottle(s) for these ZT series drives? No problem if it's slightly overfull then.

 

[Patrick0525]

@Fredward Can u post a side view picture of the oil? Can't tell how bad it is from a top view pic.

 

[Fredward]

Alright. I got it all finished and put back together and it seems to be running perfectly. I only drove it for a few minutes, so we'll see the next time I mow. The power drill idea seemed to work well. I appreciate the advice. I didn't notice much drop in oil level though. I did see a fair amount of tiny little bubbles in the fluid between purges though. I assume that's normal. I'll purge again before I mow and hope for the best. I checked the vent hoses too. They were clear. The people at toro/hydro-gear certainly didn't make this easy. What's the lifespan on these things if you don't maintain them and just drive them into the ground? What about if they get an oil change every 100 to 150 hours?

@JTK - The mower fell of the back of a truck... Haha, no. I was just being stupid. I blacked out my license plate in one picture and then noticed a serial number in another while I was at it. Force of habit from reddit I guess. I'm not actually worried about someone from BITOG tracking me down.

@Patrick - The oil from the right side transmission is still in the pan. I'll pour it back into the cup and snap a pic when this tropical storm blows over. It might be a little contaminated with some motor oil but It was empty when the oil went in.

 

[meep]

it's a PITA that these don't have drains. you went through a lot of work to do this. I was able to vacuum out just over a quart in my smaller drives with a mityvac, and it seems to have been fine. Fill height was about 3/4" below the top for mine.

 

[Fredward]

Yeah, a big PITA. I think I'll follow your lead and get a mityvac for next time. When I first cracked it open, it didn't look like any oil had volitilized. It was about 3/4" from the top. When I refilled with the same amount I took out, it brought me back to the same level. How did you check the oil level after refilling? The view is entirely blocked on my toro. Do you have one of those handy USB camera scopes? I gave one as a Christmas present last year, and I've been meaning to get one for myself.

@Patrick - Sorry, the little bit of motor oil left in the oil pan reduced the opacity to a point where another picture wouldn't have been useful.

 

[Patrick0525]

Thanks for trying.
My Ezt-2200 oil change.

 

[meep]

@Fredward - I checked the level visually, I have reasonable sight to the fill inlet though it's at an angle and not straight in. still easy enough to read without tools.