No, you didn't miss anything, LLigetfa, I was referring to the talk I had with my son about the necessity of always running at full throttle when he made the remark about never having had to mow with the throttle wide open before. So, can anyone enlighten me about whether or not that plug comes out?
hydrostatic tranny questions
Hi guys, great forum... I am working on a mower for my son, the teacher... just replaced a fuel pump and fuel hoses to fix a start/die problem, now the mower doesn't seem to want to pull itself. Moves hardly at all in reverse and not a lot better in forward. It is a yardman model Z614H which he bought used a couple of years ago. He says it has worked fine until the last 1-2 times he used it when he noticed the loss of power, especially in reverse, but also in forward to some extent. For example, he said he hardly ever had to mow at full throttle before (i know, we already talked about that) but recently he has had to to make headway. According to the manual I found online, the tranny is a hydro-gear model 311-0510 or 618-0319, which are supposed to be the same unit. I checked the belts, they seem ok. I know this is supposed to be a sealed unit, but have read here and in other places that is possible to add/remove fluid. I'd like to try changing the fluid in this or perhaps just adding some first to see if it makes any difference. On the top of the unit there seems to be a plug which takes an allen wrench. Is this the fill plug? I tried to remove it with no luck but was afraid to try too hard, didn't want to strip it out, especially if it wasn't supposed to come out in the first place, lol. Anyone have any experience with this? I have found a few references to this in other threads, but wasn't sure they were talking about the same or a similar tranny to this one. I would really appreciate any thoughts, ideas or insights into this. Thanks in advance...
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Thanks for the diagram, Chagrin. Anyone know where i could get a complete manual on the tranny? Preferably free? Also, I don't see a drain plug in the diagram, how is the best way to get the old fluid out? I really don't want to remove the tranny from the mower if I don't have to...
Ok, going to tear into this thing tomorrow, any last minute dos/don'ts/theories? I must say, after searching this forum and reading old posts, I think I may be catching the 990 bug, going to have to watch the auctions here in Kansas, see if I can find a fixer-upper... 
SUCCESS!!!:thThumbsU
Ok, here's how it went... Finally got the plug out of the top after soaking it with PB Blaster several times and letting it sit. Had to tap on the allen wrench with a hammer but it finally popped loose. Stuck a piece of wire down in there and even though I had seen no evidence of leakage, there was only about an inch of fluid in the bottom of the tranny. Decided to install a drain plug in the location diagrammed elsewhere in this forum. Used an 11/32 bit and a 3/8 tap and pipe plug. The oil was dark, but not as much as I had expected and I saw no evidence of metal filings. I let it drain overnight and flushed it with diesel. Refilled with synthetic 20w-50 and used the purging process with the rear-end blocked up so the drive wheels were off the ground. To purge, you put the tranny into "freewheel" mode, start the engine and move the trans lever into forward then reverse, slowly, about 5 or 6 times. Then take it out of freewheel mode and do the same thing. Check the fluid level. Repeat as necessary.
Ok, so we are at the moment of truth. Took it off the blocks and attempted to drive it, but there was not a lot of difference that I could tell. I remember one poster saying however that his improved after some use, so I drove it up and down the driveway (about 1/16 of a mile) for about 15 minutes. Sure enough, it improved with each lap. Never having driven the mower when it was working normally, I can't really say if it is "as good as ever", but as far as I can tell it seems to be operating "normally". It will go right up the 20 to 30 degree slope into the barn with no hesitation, even in reverse.
So there you have it. Anyone have any questions, I'll be checking back. (I'm hooked now) Thanks for everyone's help and good luck with your projects.
Ok, here's how it went... Finally got the plug out of the top after soaking it with PB Blaster several times and letting it sit. Had to tap on the allen wrench with a hammer but it finally popped loose. Stuck a piece of wire down in there and even though I had seen no evidence of leakage, there was only about an inch of fluid in the bottom of the tranny. Decided to install a drain plug in the location diagrammed elsewhere in this forum. Used an 11/32 bit and a 3/8 tap and pipe plug. The oil was dark, but not as much as I had expected and I saw no evidence of metal filings. I let it drain overnight and flushed it with diesel. Refilled with synthetic 20w-50 and used the purging process with the rear-end blocked up so the drive wheels were off the ground. To purge, you put the tranny into "freewheel" mode, start the engine and move the trans lever into forward then reverse, slowly, about 5 or 6 times. Then take it out of freewheel mode and do the same thing. Check the fluid level. Repeat as necessary.
Ok, so we are at the moment of truth. Took it off the blocks and attempted to drive it, but there was not a lot of difference that I could tell. I remember one poster saying however that his improved after some use, so I drove it up and down the driveway (about 1/16 of a mile) for about 15 minutes. Sure enough, it improved with each lap. Never having driven the mower when it was working normally, I can't really say if it is "as good as ever", but as far as I can tell it seems to be operating "normally". It will go right up the 20 to 30 degree slope into the barn with no hesitation, even in reverse.
So there you have it. Anyone have any questions, I'll be checking back. (I'm hooked now) Thanks for everyone's help and good luck with your projects.
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