Replacement of leaking axle seal in 1601

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agirlandhertractor
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Replacement of leaking axle seal in 1601

Postby agirlandhertractor » Mon Apr 07, 2014 7:35 pm

Here is a real quick how-to. All of my notes were logged here, so if you want more back & forth take a look.

Long story short, you cannot easily remove the axle to get to the seal on the 1601. The entire back end of the tractor must be disassembled. Other Yanmar models are engineered a little different - some may use this procedure and a few you can actually remove the end of an axle much simpler.

This deals with the 1601 series (ym2000 may be similar).

First, remove wheels, rear fenders, roll bar, and seat assembly. Next, remove the hydraulic assembly that sits on top of the differential. It is heavy. If you've never had this part off before the gasket will make it tough to remove. Use a pry bar in this location to help break the seal:

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Now you'll have access to the PTO assembly which must be removed. Do not be tempted to pull just the shaft out. The entire assembly has to come out as one piece - this will make more sense as you look at the assembly diagram in your parts book. Leave it together and remove the whole hunk.

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The PTO cover may also be very hard to remove. Use some sharpened flat screwdrivers to begin seperating the cover from diff. assembly. Use care here.

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Before attempting to pull the PTO unit out, note that the PTO speed selection shaft prevents it from sliding out more than an inch or so.

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There's a bolt on the left side of the diff case that holds the PTO speed selectotion shaft in. Remove that bolt and gently nudge this shaft out by 10mm or so - it won't come all the way out and only moves a few mm's - that's all you need. Now the PTO assembly can be removed:

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agirlandhertractor
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Re: Replacement of leaking axle seal in 1601

Postby agirlandhertractor » Mon Apr 07, 2014 7:40 pm

There are two circlips for each axle, an inner and outer. Both are located inside the differential, with the outer circlip being behind the differential dog gear. You only have to remove the inner circlip for the axle to slide out. Technically you *might* be able to keep the PTO assembly in place but getting the axle back would be a major PITA. I opted to remove the PTO assembly to give myself more room.

The inner circlips are visible in the following picture.

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Start by removing the inner circlip. Next use a rubber mallet and tap the axle flange as indicated in the photo. Just tap it out enough to remove the dog gear with your hands, so they don't drop down and possibly crack the case.

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Removing the dog gear:

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Axle slid out. Note there is a large flat axle washer that goes between the outer circlip and bearing. This washer will fall off the axle shaft as it (the washer) is too wide to fit through the housing. This will be important during reassembly. Don't forget about this washer. :mrgreen: I removed it using some grabbers and set it aside so I wouldn't forget.

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Here is the axle removed from the housing, with the "outer" circlip still attached. This has to come off to get the outer bearing off, and to access the seal.

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agirlandhertractor
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Re: Replacement of leaking axle seal in 1601

Postby agirlandhertractor » Mon Apr 07, 2014 7:44 pm

Now that you have the axle removed, you may take some time to remove any remaining gasket material from the differential housing. Once that is done you will want to clean the inside of the differential case including the hydraulic oil screen.

Next, put the axle on a workbench. You'll need to press the outer bearing off the shaft. I didn't have a puller with extra long arms, so I made something that worked just as well.

This jig is four 5" 3/8" threaded bolts with four washers and nuts. I'm careful to hold the bolt still while the nut is spun with a wrench. I guess you could spin the bolt but it might leave score marks on the axle. YMMV

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If you've never changed the axle seals you still have the old two-piece design with seal and collar. The collar will still be lightly pressed on the shaft. A pry bar will pop it right off.

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Collar removed:

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Here's the new one-piece seal that replaces the old parts:

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agirlandhertractor
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Re: Replacement of leaking axle seal in 1601

Postby agirlandhertractor » Mon Apr 07, 2014 7:46 pm

ASSEMBLY

First apply some grease to the seal:

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And to the bearing surface on the shaft too:

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I used a section of 2" PVC pipe to drive both the seal and bearing down on the axle.

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agirlandhertractor
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Re: Replacement of leaking axle seal in 1601

Postby agirlandhertractor » Mon Apr 07, 2014 7:49 pm

Remember the washer that goes next to the snapring I mentioned earlier? Well that has to be tossed into the axle housing and put on the end of the axle shaft as it slides in. It won't fit through the housing if it's actually slid on the axle. Weird but once you see the housing this will make sense.

PITFALL:
You may be tempted to bump the axle back in place and tighten the four flang bolts. Don't, you have to get the dog gear on first. I speak from experience: :mrgreen:

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Getting the axle and dog gear back in place is not easy since the inner bearing is lightly pressed into the housing, and tightly pressed on the axle. It wants to push off of the housing every you tap the axle in.

I don't have pictures here because I literally had my hands full with what I was doing. I got a porta-press from Harbor freight and used that to help push the dog gear and inner bearing back onto the axle and into the differential housing. If that last sentence sounds complicated that's because it is. You'll need the porta press, 10mm press attachment, and some spacers that will hold up to some pressure. Use extreme care here - not only for your own safety but you don't want to break anything. Go slow and know what you are doing in advance. Wish I'd taken pics of this stage but it was messy. You may find a better way of doing this.. if so, post reply with info.

Here's the left dog gear reinstalled.

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Differential all cleaned up:

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The last thing is to reinstall the PTO assembly and hydraulic cover. I won't list out step by steps for this.. just read through disassembly and basically reverse it.

A parts manual is helpful in all of this. The domestic equivalent repair manual is worthless: the axle & diff assemblies are a little different and the pictures were also blurry and dark nearly blacked out in some cases. Save your money and get the parts book. It was more helpful.

If anyone has questions feel free to post back and I'll try to answer & help. This job was difficult and took the span of a couple weeks including waiting on parts and a full time job.
Last edited by agirlandhertractor on Tue Apr 08, 2014 6:47 am, edited 1 time in total.

winston
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Re: Replacement of leaking axle seal in 1601

Postby winston » Tue Apr 08, 2014 6:06 am

Great job, thank you.


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