TN75 Hydraulic Leak at 3pt and resevoir

[ezslim]

Hi Gang,

Since my 2005 TN75DA has made a hobby out of spewing hydraulic fluid all over my shop floor, the latest leak isn't too much of a surprise. I've isolated a static leak at the shaft/bearing that supports the lower 3 point hitch attachment (left side). As I looked at the Messicks diagram, it appears there is one two-part seal and one O-ring that allow that attachment axle to rotate inside the hydraulic resevoir. $50 later, I had the seals and a nice Saturday to take things apart. The locking bolt and swing-arm came off easily and the housing bolts came out, but that's when the fun stopped. The housing "should" just pop off, exposing the seals, but it appears to be machined into the housing? Any help on removing the mounting flange (housing) is appreciated.

Thanks,
Slim

 

[RickB]

With the two mounting bolts removed, use a hammer & drift to rotate the seal/bushing housing until part of the mount flange is exposed below the differential housing. Carefully tap the flange away from the housing until you can get a narrow chisel in the gap to complete the removal.

 

[ezslim]

Thanks Rick,

I'll give the hammer and chisel a try. I was concerned that the flange was so tight in there and I didn't want to damage it (like I am prone to do with a hammer). Harry also PM'd me and gave me some additional parts to consider. I'll have to get it apart to see exactly how it's assembled, and therefore, what I need to replace, but it sounds like he's done this before. Will let everyone know how it comes out.

Slim

 

[RickB]

Anybody that works on TN tractors has probably done this repair.

TN70- name the part - TractorByNet.com

 

[ezslim]

The problem with having a great Air Force job is I never get home to fix my tractor in time to actually USE it!

I finally got the supports off the differential housing, managed to weasle the snap ring out, pushed the eliptical bushing out with a deep well socket (poor man's arbor press), but now I'm stuck on how to pull the outer seal out of the support housing without scarring the support housing. The plastic on the seal is trashed, so I know where the leak came from, but the seal housing is in there pretty tight. Any machinists/masochists out there know how to pull the seal out without damaging anything? Thanks, Slim

 

[Harry in Ky]

I keep a couple old screwdrivers just for things like this. Grind a U shaped indentation in the tip similar to a bushing cutter chisel. Keep the edge blunt, don't sharpen it, so it won't score so badly. Just catch what you can of the seal housing through the hole, and with a little patience and practice you'll soon get the hang of it.

 

[1bush2hog]

Must be the season I sprung a leak after bush hogging this past weekend.

Is this the area you are talking about?

 

[ezslim]

That's exactly the spot! It seems my Bush Hog worried the little bushing enough to create some "slop" that exceeded the limits of the exterior seal. With the weight of the implement on the seal, it allowed the hydraulic fluid to really run out, especially when hot. I'm not sure of how to prevent it again, other than to take more time with the bush-hogging so I don't beat up the internal bushing too badly.

To repair mine, I took both housings to Sears (of all places) since no other machine, tractor, or auto shop had a blind hole puller. I could drive the bushing out on my own, but couldn't get the seal (pastic came out easily, but the metal casing stayed tight - even with the very good tip about grinding a special driver). Sears charged me $20 a side - a bargain considering I had already spent an entire day of leave running around town looking for a puller or a shop to do it for me. Never thought they'd come in handy for the farm, but thank-you Sears Auto Center!

While I had everything apart, I polished the rod that goes all the way through. It had become pitted and "rusty" in spots, particularly where the seal needed a good surface. That may have contributed to the seal failure as well. There was some debris inside the seal as well, so I'm not sure if it arrived after the seal failure, or contributed to it.

To smooth the rod, I used the brass wire wheel on the dremel, then some rubbing compund, then some polishing compund. I smeared the whole thing with marine grease for assembly and slid it all back together. I was able to mow about 40 acres in two days using my batwing instead of the 3-point bushhog with no leaks noted.

Thank-You to all who contributed to the repair. You saved a very expensive dealership call ($200 just to visit the farm). The repair was very manageable once I got the bushing and bearing out of the housing.

 

[allenbs]

on my tn75 new holland, i believe the hydraulic fluid is low, where do you put it in at and how high should show on the dip stick.
I think it goes in there on the rear end , on the right side i just wanted to make sure.

 

[howierd3866]

it goes into the same hole where your dip stick goes..and on the stick theres lines which is hard to see fluid on but it show up