Trouble getting cylinder out

[marksto66-HT]

Following up on my thread from earlier this week where I managed to get the stuck lock valve working in an effort to repair a hydraulic leakdown on my YM186.

As Aaron acknowledged in an earlier post, unfortunately on my model removing the hydraulic piston for the three point to replace the o-ring involves removing the whole PTO assembly and backing the cylinder assembly out the rear. I've removed the hydraulic line and hydraulic cover to expose the cylinder, removed the lower hinge unit and am now trying to remove the PTO and am stuck.

The service manual is woefully unclear about the process of removing the PTO shift lever. It reads: "Remove PTO shift lever or loose lock nut and pull shift arm out." I have no idea what they mean by "or" - as it would seem the only way the remove the lever would be to loosen the nut and pull the arm out. But alas, it's not that simple. I've loosened the locknut completely but after a certain point it runs out of threads and won't loosen any further. See the photo below by the red arrow. I'm thinking the whole lever needs to slide off it's shaft to come out, but I've banged and banged and used a crowbar to try to pry it out and cannot get that lever to move at all.

The I figured maybe it's not supposed to come all the way off but rather by loosening the locknut I've backed it out enough already that the PTO assembly will come out. Drained the transmission/hydraulic fluid, removed all 10 bolts holding the PTO to the rear and it will not budge. Again, I've banged and pried on that PTO cover all I dare and it does not move. Which makes me think the PTO shift lever is still holding it in place...

<help?>

<IMG src="http://i284.photobucket.com/albums/ll5/marksto/Picture008.jpg"><s>

</e></IMG>

 

[Norm-HT]

"Remove PTO shift lever or loose lock nut and pull shift arm out."

It's never a good idea to change threads in mid-repair, but I assume it means "remove pto shift lever and loosen lock nut and pull shift arm out".

 

[Aaron-HT]

I think they just want you to remove the shifter lever so that the internal lever can pivot enough for the pto assembly to slide out. With the shifter lever on there it will hit the frame before the lever inside can pivot enough. I would just drive the roll pins out of the lever and move on. The manual should have an exploded view at the end. Take a look at the shifter assembly.

EDIT- I just added the diagram in an attachment. You can see in the image that removing that nut wont accomplish anything.

 

[marksto66-HT]

Allow me to state, for the record and for anyone trying to remove the PTO off a YM186, that the confusing statement in the service manual that implies the shift arm must be removed is WRONG. I speak from considerable experience after hours of trying in vain to get the shift arm off believing it would prohibit me from accomplishing the PTO removal...

In its place that sentence should read "Loosen shift lever lock lock nut to faciliate seperation of the shift arm from the remainder of the PTO assembly."

In reality, there is no permanent connection between the shifting mechanism and the PTO. In fact, it would probably come out quite easily even if the nut weren't loosened and nothing was done with the shift lever. The pin shown at the bottom of part #30 above simply slides into a slot on the PTO. By loosening the lock nut on the lever, a little extra wiggle room is created so that by slightly turning the PTO assembly to the right as it pulls out that pin comes out of the slot and out will come the whole assembly.

Now on to the blasted hydraulic cylinder...

 

[marksto66-HT]

Ok, well here I am with the next problem of the day - how in the world do I get the hydraulic cylinder out so I can complete the process of replacing the piston o-ring?

Service manual simply says to remove the set screw and slide cylinder out to the rear. But of course it can't be that easy. I presume the front of the cylinder that goes into the housing where the set screw hole is must have a super tight seal because it holds hydraulic pressure just like the piston. And of course that seal means it won't come out...

It quickly became obvious that just using my hands through the open hydraulic cover to twist and pull a smooth cylinder would lead to nowhere. I couldn't figure what else to do so I wrapped a heavy gauge wire around the tapered front end where it could gain grip, and then fed the wire out the rear of the open PTO hole and pulled with all my might for 30 minutes. I managed to move it maybe 1/8".

Am I missing something here? Is there a trick to get this damn thing out?

<IMG src="http://i284.photobucket.com/albums/ll5/marksto/Cylinder.jpg"><s>

</e></IMG>

 

[Aaron-HT]

I have never had to remove one of those but my guess is that there would have to be an oring on the outside of the liner to seal it (#12 OR #11... I'm at home so I cant look it up right now). Sometimes you have to pull out perfectly straight. Maybe your wire is pulling it off to one side too far &amp; it is binding? Not really sure. Wish I could be more help but that is as far as I have ever gone.

<IMG src="http://hoyetractor.com/CATALOG/1510/IMAGES/THREE-POINT-LIFT.jpg"><s>

</e></IMG>

 

[Norm-HT]

I don't believe I have ever read of anyone having to remove the cylinder in order to get the piston out. Are you sure that's what the book says?

 

[marksto66-HT]

Ok, maybe that's what I'm missing here...?

I'm at work without it in front of me, but I'm thinking the service manual does not state explicitly that the cylinder HAS to be removed, but the section on it begins with removing the cylinder and then proceeds with describing how to disassemble, remove the piston, and replace the O-ring. Since the piston (#13 above) is currently recessed way in the front of the cylinder (up by where I've got the wire attached in the photo)I presumed that to get it out would mean removing the cylinder, disassembling, and using something to push the piston out the open rear from the front.

Without removing the cylinder, how would I get the piston to come out?

 

[marksto66-HT]

Alright, now that I'm home and have reviewed the service manual information I find that the directions clearly infer removing the cylinder before extracting the piston. More specifically it states (after the instructions on removing the cylinder) "remove piston with O-ring and backup ring" then beneath it says "use pressurized air or stick to push out piston."

Obviously I cannot use a stick unless the whole cylinder is out, but the reference to using pressurized air makes me wonder if that might not be a way to get the pistion out while leaving the cylinder in place. If I get a blow gun with rubberized tip, perhaps I can stick it in the hole that leads to the front of the cylinder and use it to blow it out. Does anyone have idea how much pressure would be required to accomplish that? If it really takes a lot then I may not be able to get enough seal with the rubber tip to make that piston move.

If I do manage to get the piston to move I'll have to take the piston rod out to allow it to come out completely - see picture below. The piston rod is held in place with a "spring pin" which is a hollow pin with a slot running down the side. Is there a special tool to remove such a thing or do I just get a punch and start hammering?

I'm also curious how this all works on other Yanmars. I'm under the impression that this piston O-ring replacement is a relatively common maintenance task. Is the design on the 186 so different that all these directions are foreign? How would one go about removing the piston on other models?

<IMG src="http://i284.photobucket.com/albums/ll5/marksto/Yanmar.jpg"><s>

</e></IMG>

 

[Aaron-HT]

<QUOTE><s>

</e></QUOTE>

Yes.

<QUOTE><s>

</e></QUOTE>

The piston, liner, and rockshaft all come out with the top cover. Very easy.

On the 186- can you not slide the rockshaft (#19) out &amp; let the arm (#17) fall out? Then the piston can pull straight out?

 

[marksto66-HT]

<QUOTE author="Aaron"><s>

</s><QUOTE><s>

</e></QUOTE><e>

/e></QUOTE>

Right, if you look carefully at the picture, it was taken with the lift arms raised as high as they will go, and as the rockshaft (#19) pivots up it hits the frame before the piston rod is out of the can. Therefore, either the cylinder has to come out or the piston rod has to be taken off before the piston can be removed from the cylinder.

I wish I had known how difficult this was on the 186, I never would have started if I had. However, I hate to give up now that I'm 95% of the way there. At least I'm spreading the information and experience and leaving a trail here on the forum for anyone else that comes along with the same problem on this model.

 

[Aaron-HT]

I think you missed what I said. I'm saying remove the lift arms completely. Then pull the shaft (19) that the arms were attached to out. The piece that the connecting rod is attached to (17) is then free to fall down out of the way along with the connecting rod. Then you can use the air to blow the piston out.

Actually, the better instructions are in the previous section in the service manual.

 

[marksto66-HT]

Hooray! The cylinder is out! - thank god...and Aaron.

I guess I wasn't seeing the forest for the trees - or the piston rod for the lift arms as it were... Followed Aaron's advice, disassembled the liftarm mechanism, removed the piston rod, one quick blast from the air gun and the cylinder flew right into my grateful, welcoming, open arms.

Upon inspection, I don't see any obvious damage to the o-ring but it does seem pretty flattened. There are also a series of pretty good scratches, a few bordering on light grooves, etched into the steel where apparently some bits of metal or other debris got in there through the years. Posted a picture below, although it's hard to get grooves clearly visible with a flash photo and it may be pretty hard to gauge the severity from the picture. I hope this kind of damage is relatively normal and that after all this I don't have a leak caused by permanent damage to the cylinder itself.

Tomorrow I'll order new o-rings, gaskets, and various other maintenance parts from Hoye and in a week or so I'll be reversing the process, re-assembling, and hoping like hell after all this that I have no more leakdown!

<IMG src="http://i284.photobucket.com/albums/ll5/marksto/piston-1.jpg"><s>

</e></IMG>

 

[Aaron-HT]

<SIZE size="200"><s></s><B><s></s>Hurray!<e></e></B><e></e></SIZE> <E></E>

 

[Carey-HT]

Good Job. Couldn't help not to follow this one.I had a feeling you were real close to getting it out.I seen the post up first again and was wondering if it finaly just about fell out. It's all good and behind you now. at least you had to put the air to it <E></E>

Carey

 

[marksto66-HT]

Just thought I’d post a final followup to the odyssey of repairing the hydraulic leakdown on my YM186.

I’m happy report that thanks to the help and support received here and once I got all the parts from Hoye I was able to get everything re-assembled and back in working order. Best of all, the leakdown is definitely fixed. Once lifted those lift arms do not move at all!

The only small issue I encountered with the re-assembly was that at one point I dropped one of the lift arm o-rings into the small pool of transmission fluid just inside the PTO hole, and when I fished it out I was surprised to first pull out another wayward piece of debris. A rather large sliver of white poly/plastic about 3 inches long and slightly curved. I have no idea what it was from but presume it had been in there a long time.

I must say I have a large degree of satisfaction in having accomplished the hydraulic repair and other overdue maintenance tasks this winter. I bought my 186 about 5 years ago and put it to work immediately with lots of mowing here in the long Florida growing season. I know little about its past history, and this is my first tractor. The 186 is one tough little beast and I was very fortunate to have picked it up for $1300.

Before this winter I had never had the facility or time to really go over it and perform thorough, non-urgent type maintenance. In addition to the hydraulics I also gave it its first really good cleaning, installed a temp gauge, did brake repair/maintenance, wheel stem repairs, and a valve adjustment. The valve adjustment has already made a noticeable difference, it starts much more quickly and just feels and sounds like its running better with improved compression.

Anyway, thanks again to Aaron and others. This forum is a terrific resource and I plan to continue to stick around.

Mark
Tampa

 

[Anonymous-HT-0-HT]

Most enjoyable and informative post. Glad things have worked out for you.