JD 855 Transmission Seal Leak

[Wyobuckaroo]

I also have a 1987 JD855, with about 800 hours on it. Bought it late last summer with 750 hours. Has not been a problem so far.

After looking at the exploded pictures of the tranny and drive shaft, I suspect you are talking about replacing the part #42 cover with one that has a groove in it to accept a snap ring. And the ring #61, for $300..........

On the drive shaft view, I would start from the front and work my way back. That is motor mounts are tight. Check that there is no signs of movement, forward and back, on parts #1-2-4 that would indicate the drive shaft was pulling or pushing the main shaft from the tranny out of position.

Then with no internal air pressure in the tranny case, vent good, filler cap loose. It would have to be a "over pressure, lack of relief" problem in the tranny thing?

Also, if the same pump provides pressure to the hydrostatic as the 3pt hitch, hydraulic systems, wouldn't that confirm a diagnoses of a bad pressure relief/bypass situation ?

Good luck
Wyo

 

[dfkrug]

There is no sliding expansion section like a car driveshaft (or the driveshafts on my mowing deck and brush hog), so I am wondering if I need to unbolt the front of the driveshaft from the engine flywheel and work the U-joint around to where there will be enough clearance to pull the whole assembly away from the hydro input shaft? Or is there not even enough clearance at the flywheel to get the front free? In which case, it looks like the only way to get it out would be to press apart the U-joint?

The yoke (#7 in your 2nd drawing) will slide on the spline shaft if the
bolts are loosened. The rubber coupler (#2) is where you detach the
drive shaft from the flywheel. The engine moves around a bit on the
rubber engine mounts, so sometimes you can pull the drive shaft off at
the coupler without messing with the spline shaft.

Of course, that means the engine mounts are broken, which is a regular
problem on x55s. I replaced broken engine mounts on 3 of the 4 955s I had.

Is there enough clearance to pull the whole driveshaft off at the yoke
once you have separated the coupler? That's a good question, since
I did not do it that way. I was removing the engines on my 955s.

I certainly can see the back end of the charge pump (where the seal
goes) costing $300. Getting a new one may be necessary if there is
no circlip groove.....

 

[suchaski]

I received the new housing, seal, snap ring, etc. from John Deere and after removing the installed housing (piece of cake) and comparing them, the old one does not have a snap ring groove in it like the new one does. Installed it last weekend and pushed my 855 to the max getting ready for spring/summer. No leaks what so ever!

I tried to accomplish this same fix last year when it did it, but I would bet a month's pay (what little that it is) that the parts breakdown from a year ago did not show the housing with a snap ring like it does this year.

I would take it that my OEM housing that was put on during manufacture was correct but somehow the Gods smiled down (as well as others having the same problem) that they changed it. Maybe it was always on the 955 and not on the 855, but they both work on either one.

Either way, I appreciate all the input........

 

[BobInVT]

Just a follow-up on my prior post on page 2. I managed to get the driveshaft out without removing the engine or loosening the motor mounts or even removing my snow plow blade. Reference this drawing:

After loosening two nut/bolt #9/10 on both sides of the spline shaft, remove the three bolt #3 from the other end of shaft, then remove the three bolt #11 as well. Pull the shaft toward the hydro drive (it will slide backward an inch or more on the splines) and then spacer #2 will drop out. That gives you enough forward clearance to pull it the other way to remove the yoke #7 from the splined hydro input shaft. At some point in this process, you'll need to pivot the U-joint to get it all out of the way. But ultimately, I was able to do this on my 855 with the snow blade/mount installed. Plus, I was able to replace the hydro input seal from the top side without even having to remove the hydro oil filter.

It ended up being a semi-expensive repair because my old air wrench did not have the power to turn the #3 and #11 bolts so I had to buy a new one with something like 740 ft. lb. torque. But then those bolts just unscrewed and came right out.

So a $200 tool to replace an $8 seal but now I have a macho air wrench and saved the expense of having the Deere dealer pickup/repair/return which probably would have been at least $300 and probably more like $500+.

I did this about 6 weeks ago and have not had any further leaking. My tractor was made in 1990 and the front hydro cover does not have the retainer ring groove either, but I don't think mine had popped so much due to over-pressure as it did because of the continued pounding that the whole frame was taking slamming snow into the old frozen banks. Hopefully, I'll get another 20 years out of this seal! Just pulled the snow blade off today in preparation for mounting the mowing deck, and that reminded me to come in and post this update.

 

[BobInVT]

Dredging up this old post to add more info -

So my 2011 seal only lasted 4 years. I knew just how to replace it when it blew again this year. But the new one I put in only lasted a couple days. Finally decided to cave and buy the new housing that includes the groove for a snap ring to retain the seal.

$337 part

I took pics to show the difference between the two housings, top one w/o groove, bottom w/groove:

Changed it out a week ago and so far so good, though I've only needed to plow once since then.

Part #42 on the diagram on prior page. JD #M115136. Snap ring is M115137.

 

[dfkrug]

So my 2011 seal only lasted 4 years. I knew just how to replace it when it blew again this year. But the new one I
put in only lasted a couple days. Finally decided to cave and buy the new housing that includes the groove for a
snap ring to retain the seal.

Good clear photos, Bob.

It looks like the new part has a taller shoulder than the old, to allow for the snap ring, no doubt.

I never had this problem with all 4 of my 955s, so I suspect the later units had the snap ring.

Rather than buy such a spendy part, perhaps welding a retaining ring (removable) would work, too.