311-3500 Hydro Gear

[madmantrapper]

This is on a 917.276120 Craftsman GT. Anyone here had one apart? This one acts like it is getting hot and slipping. I was plowing the garden and it just would not pull normally. I disconnected the plow and got it back up to the garage, it would hardly pull and acted like the pulley was slipping on the shaft. It would jerk occasionally. Anyway I let it sit for a day or two and going to pull it apart. I was moving it the garage and it seemed to work fine. I moved the grass without issue. Today I was mowing some very heavy areas and noticed it was not quite right. I am going to try changing the oil first, I know it has never been changed. The info I found on it says it uses a 20W50 oil. It has 2700 hours on the hour meter. Any know where to drain the oil and refill?

[KE4AVB]

Hours is probably more like 270.0 hours. It is hard to see the decimal sometimes.

Oil change should be the same as 310 series. It will require the removal of the hydro transmission as must drained thru the fill port which is on the top of the unit. It looks like you are going about 4 qts of 20W50 for the change.

The closest service manual that I could find is for the 310-3000. It should at least give you the basic info you need for servicing.
http://www.hydro-gear.com/Main/docs/service-repair-manuals/310-3000.pdf

[madmantrapper]

Hours is probably more like 270.0 hours. It is hard to see the decimal sometimes.

Oil change should be the same as 310 series. It will require the removal of the hydro transmission as must drained thru the fill port which is on the top of the unit. It looks like you are going about 4 qts of 20W50 for the change.

The closest service manual that I could find is for the 310-3000. It should at least give you the basic info you need for servicing.
http://www.hydro-gear.com/Main/docs/service-repair-manuals/310-3000.pdf

Its 2700 OK. Thanks for the link. I looked all over it and could not find any drain plug. It does not look to hard to remove.

[KE4AVB]

2700 boy that been a good one then. Don't usually see mowers with hours like that here even my JD 650 has only 2400 hrs and it took me 20 yrs to get there with mowing 11 acres and other farm work.

[Mek-a-nik]

Sounds like hours is the problem, but, I've seen debris built up between the clutch pedal and it's stop, not allowing the belt to tighten fully. Depends, of course, on the design.

[madmantrapper]

Yea it is a lot of hours alright. Grandkids think it is a means of transportation. I've changed the oil as often as three week intervals before during the summer.

I checked for debris but found none. The cooling fans has always been kept clean. I think I am going to pull it apart early next week. I don't see any signs of oil leakage. If I don't see anything too nasty while dumping the oil, I may just refill and try it again. All those hours on the oil seems a little excessive. The only thing is it did not seem to go out gradually but all at once in a matter of 20 minutes or so. I'll let you guys know what I find.

[wristpin]

Any difference between forward and reverse?
You will be very skilful/lucky/fortunate if you can extract all those horrible little "torque screws" that hold the casings together without shearing one or two. Light hand and patience required. Hot air gun can help!
If it were not for the "sudden " failure I would say scoring on the interfaces of the pump/motor cylinder blocks and the centre case. Be interesting to know what you find.

[bgsengine]

Any difference between forward and reverse?

Excellent question there.

You will be very skilful/lucky/fortunate if you can extract all those horrible little "torque screws" that hold the casings together without shearing one or two. Light hand and patience required. Hot air gun can help!

So true

If it were not for the "sudden " failure I would say scoring on the interfaces of the pump/motor cylinder blocks and the centre case. Be interesting to know what you find.

Actually, I would suspect scoring anyway - looking at the high hours, I would not be the least surprised that a metal shaving (due to normal wear) finally broke off some edge of a slipper plate and cut you a nice groove between the pressure passages which would account for a sudden failure.

I've seen that before on similar design Sundstrand hydrostats (but rather than the 1-piece aluminum blocks in the hydrogear the SS was cast iron block with a Bronze coated steel slipper plate which , way back when, we'd spend a half hour each on a piece of thick glass with 600 grit wet-dry sandpaper to remove the grooves in the valve blocks and mating plates.) - when they get into the high hours, that normal wear on the blocks caused tiny thin shavings of the brass coating to peel away and then it'd go through and cut grooves in things where there shouldn't be any.

[madmantrapper]

There really isn't any difference between forward and reverse. Reverse has always been slow but I think that was safety thing from the factory. I have a heat gun so that will help.

I let you know what I find and take some pictures.

[madmantrapper]

Well I finally got to look into the thing yesterday. Removal was a piece cake. Took longer to get the wheels off then to remove unit. Unfortunately none of the pictures turned out, grandson left the card out of camera. Anyway drained oil and it looked like new. No slivers in it of any kind. Magnet picked up nothing. Only thing I found was a piece of stuff that looked like gasket sealer that oozed out somewhere. Refilled with 20W50 and put back in. I'm going out to try to purge it and get it going in a minute or so. I'll let you know how it turns out. I can't see it being any better just by changing the oil but as easy as it is to remove I figured I'd try it.

Paul