1983 YM336D - How bad is this? Worth fixing? (warning: graphic images of broken bits)

[Domush]

So far things have been progressing along nicely, until now..

I finally got my factory service manual and, emboldened by the directions, went outside to check on the hydraulic system, as the 3-pt lift would not work when I bought this tractor. I removed the hyd screen cover and screen (after draining all the fluid) only to find 5 bolts (two sheered off) and what appears to be a round steel plate with 3 holes in it, just floating around at the bottom of the case. I also pulled, via magnet, two 3-hole bolt head locks (the type with tabs which lift to prevent unscrewing.. apparently these didn't work so well). Also found were a few ounces of metal shavings.. always a really bad sign. I can only guess the shavings are what used to be the threads of the bolt heads. This is most assuredly not a good thing.

Unfortunately the service manual does not have a parts breakdown of the lift mechanism, so I'm left guessing what these parts are and how to best access them for inspection/replacement. Does anyone know what these are and maybe have a scan of a parts breakdown?

I'd greatly appreciate any help, here, as I'm beginning to get in over my head on this tractor. Maybe selling it as-is and continuing the search for a decent one is in my future. I just don't want to wait another 5 months finding a decent deal.. though I also don't want to spend 5 months fixing what may not be affordable to fix. I already have a boat which meets that description, except it is going on 3 years .

Any tips? advice?

How difficult is it to crack this housing open to diagnose/fix this?

(Photos attached)

 

[clemsonfor]

I to have no idea what that is from. But your 3pt hitch is ontop of the transmission. Lift the seat foward and look, you will see the whole top part will bolt onto the tranny with like 15 bolts or so. All you need to do is disconnect the hard hydro line from the valve take the linkage loose and remove those bolts and the lift arms from the lower links and the whole top will come off. That is the whole 3pt system in your hands minus the pump and lines. The piston is in there the rock shaft and all. You will be able to see what is going on from there better as the whole top of the tranny will be exposed. This is your next step before going farther i think. But that much metal is not good.

Edit, i should say all the other yanmars i have seen are like this. Yours is a little bigger model but i would assume its the same.

 

[Domush]

Sure enough, the top was easy as pie to remove. Just 6 bolts and the hydro line. I found what happened and removed all of the broken bits. The question which remains is.. how did this happen?

It seems I'll need to remove both sides of the rear axle, which sucks, but seems doable. Extracting the broken bolts may prove troublesome, but hopefully the hydro fluid kept the threads from seizing up. The broken bits are the bolts which hold on a plate which, in turn, seems to hold each side of the axle in place. Oddly, both sides popped, not just one. Otherwise, everything seems to be okay. Though I did magnet out some bits which looked eerily like gear teeth, but have yet to find any gears missing any.

Still a bit scared tearing this down so much. I've never done something like this on a machine this size. My background is in small engines, not tractors.

 

[clemsonfor]

Sure enough, the top was easy as pie to remove. Just 6 bolts and the hydro line. I found what happened and removed all of the broken bits. The question which remains is.. how did this happen?

It seems I'll need to remove both sides of the rear axle, which sucks, but seems doable. Extracting the broken bolts may prove troublesome, but hopefully the hydro fluid kept the threads from seizing up. The broken bits are the bolts which hold on a plate which, in turn, seems to hold each side of the axle in place. Oddly, both sides popped, not just one. Otherwise, everything seems to be okay. Though I did magnet out some bits which looked eerily like gear teeth, but have yet to find any gears missing any.

Still a bit scared tearing this down so much. I've never done something like this on a machine this size. My background is in small engines, not tractors.

These things are fairly simple and your clearly doing fine. Think of it like i do. If aint right now, your not gonna hurt it. Worst case you take the pieces to a mecanic that charges you to reassemble.

 

[kenmac]

You've come this far. I think you'll do just fine. You'll know more about the tractor making the repairs yourself. Those bolts may have had loctite on them to keep them from backing out .I would apply some B-4 assembly. those bolts maybe something like a grade 8

 

[Neat 1500]

that filter almost looks to be rusted out, it has had water in it for a loooong time i'd say. the hydraulics for the 3PH have prolly rusted up.

 

[MJPetersen]

You do understand that the broken bits that you showed have nothing to do with the hyd not working. With the amount of rust on the filter, I would say that it had a heavy load of water in there and you may have more rust in not so nice places. But you have most of that off already in the control valve, and in the piston/cylinder.

Mike

 

[Johndeere3720]

I just happend to fix the hydraulic lift problem on my 169D about a month ago. It actually isn't that hard to do. First thing I did was tested the hydraulic pump which came out okay. So I pulled the top housing off the transmission which houses the cylinder that lifts the hitch up and down. Pulled out the cylinder head and there was a O-ring around the cylinder head that was dimpled and shot. $4 and a trip to Kubota was all it took, they are more likely to have the right O-Ring since John Deere doesn't carry these O-rings in stock and don't carry the right size. The O-ring is critical, with a small gap in it this allows the pressure from the hydro pump to escape and just go into the transmission. It was a 2 day fix for me, one spent checking the pump and the other pulling the cylinder off. Also, when it comes to cleaning your hydraulic screen, scrub it in gasoline or diesel and get it as clean as you can. Then use an air compressor and blow it clean. They are not easily replaceable parts, that being said it is not likely you will find a new one for sale, it is likely that you could get a used one from hoye if it is rusted through. The transmission case on your tractor should be aluminum so that should be okay but the gears are not so i would check them out while the transmission is drained to make sure everything is okay.

 

[Car Doc]

I looked at my 336 manual last nite and I didn't even see anything that resembled the broken parts so I sure cant help sorry but looks like you are well on the way. :thumbsup:

I would have been happy too if I could have found it but my crappy photo copied manual the pics are horrible in it makes me wonder about when I need it for me.

One thing I did notice while looking for those parts is that tractor has a built in pto overrun clutch. Maybe all us models did I dont know but that is pretty neat feature not as easy to repair as an add on but doesn't make you shorten a drive shaft either for an attachment.

 

[rmully]

That clogged and rusted filter could be 90% of your problem. I would open it up and look around.