hyd cyl repair and axle seal repair

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cootbruce

Member
Joined
Apr 6, 2004
Messages
8
First of all...thanks for the work on the site and for adding this area. Since I had a hand in suggesting it...I thought I should get the ball rolling with a post...... The hyd Cyls on my bucket on my Bobcat are leaking. I have not worked on these before..what should I expect to find and how should a go about it. Will I need to pull the entire cyl off the machine to change the seals, or can I disconnect the cyl from the bucket and pull the insert out of it??? Are the seals held in with set screws??? This is a old M600 machine. Also, will soon have my parts back to reinstall my axle. Had a leaking axle seal. Anyone have any experance puting one back together?? If so....any special things to do to ensure it won't leak when put back in....??? Thanks for any advice.
 

500K_773

Well-known member
Joined
Mar 5, 2004
Messages
342
It's been awhile since I've rebuilt any hydraulic cylinders, but remember it was pretty simple. IMHO, It will be easier and less messy if you take the cylinder off the machine. It is a good idea, but not necessary to buy some plugs and caps for the fittings and hoses to prevent leakage and protect the threads on the fittings. The hydraulic fittings should have a size stamped on them, ie. -12 is a 3/4” fitting and -8 is a 1/2” fitting (note the number is a 1/16” increment). A spanner wrench will probably be needed to unscrew the cap. It is important to check the rod for scoring and nicks that may tear the new seals. Minor damage is not too bad and should work well for awhile, but severe scoring should be addressed. I don't know how much your Bobcat dealer would charge for a new rod, if needed, but a good hydraulic shop could probably build you one cheaper. Use care during reassembly with the new o-rings and lubricate well. Keep everything clean, any dirt or metal pieces will end up in your hydraulic system. If you plan on changing your hydraulic filter after repairs, it is best to test everything first in case you have to tear it apart again to fix a leak.
I don't have any experience with Bobcat axle seals, so I'll leave that for someone else.
 

500K_773

Well-known member
Joined
Mar 5, 2004
Messages
342
It's been awhile since I've rebuilt any hydraulic cylinders, but remember it was pretty simple. IMHO, It will be easier and less messy if you take the cylinder off the machine. It is a good idea, but not necessary to buy some plugs and caps for the fittings and hoses to prevent leakage and protect the threads on the fittings. The hydraulic fittings should have a size stamped on them, ie. -12 is a 3/4” fitting and -8 is a 1/2” fitting (note the number is a 1/16” increment). A spanner wrench will probably be needed to unscrew the cap. It is important to check the rod for scoring and nicks that may tear the new seals. Minor damage is not too bad and should work well for awhile, but severe scoring should be addressed. I don't know how much your Bobcat dealer would charge for a new rod, if needed, but a good hydraulic shop could probably build you one cheaper. Use care during reassembly with the new o-rings and lubricate well. Keep everything clean, any dirt or metal pieces will end up in your hydraulic system. If you plan on changing your hydraulic filter after repairs, it is best to test everything first in case you have to tear it apart again to fix a leak.
I don't have any experience with Bobcat axle seals, so I'll leave that for someone else.
Have you tackled the repairs yet? Please fill us in on how they went.
 

cootbruce

Member
Joined
Apr 6, 2004
Messages
8
Have you tackled the repairs yet? Please fill us in on how they went.
Well, I replace the axle bearings and seals. Really not too tough, just messy. Pulled the axle out, and brought it to the dealer to have the old outer bearing and seal pulled off and the new seal and bearing pressed on. Thought it better than me trying to make a puller for this. Everything went back in pretty nice. The real test was when I filled the area back up with ATF and looked for leaks....no leaks....so I drove it.....still no leaks.....so far so good. Now that I fixed that leak, I found that my spool valve for my tilt control is leaking...waiting for the parts to fix this and my hyd cylders...then I should be leak freee!!!!!
 

jsimpson

Member
Joined
Jan 8, 2004
Messages
9
Well, I replace the axle bearings and seals. Really not too tough, just messy. Pulled the axle out, and brought it to the dealer to have the old outer bearing and seal pulled off and the new seal and bearing pressed on. Thought it better than me trying to make a puller for this. Everything went back in pretty nice. The real test was when I filled the area back up with ATF and looked for leaks....no leaks....so I drove it.....still no leaks.....so far so good. Now that I fixed that leak, I found that my spool valve for my tilt control is leaking...waiting for the parts to fix this and my hyd cylders...then I should be leak freee!!!!!
Did you have to pull the hydraulic motor to pull the axle? The manual for my 453 says I have to. My axle bearings are shot due to the stresses placed on them by solid rubber tires. I don't yet know if I'll need just bearings and seals, or axles too.
 

Goss7285

New member
Joined
Jun 22, 2009
Messages
1
It's been awhile since I've rebuilt any hydraulic cylinders, but remember it was pretty simple. IMHO, It will be easier and less messy if you take the cylinder off the machine. It is a good idea, but not necessary to buy some plugs and caps for the fittings and hoses to prevent leakage and protect the threads on the fittings. The hydraulic fittings should have a size stamped on them, ie. -12 is a 3/4” fitting and -8 is a 1/2” fitting (note the number is a 1/16” increment). A spanner wrench will probably be needed to unscrew the cap. It is important to check the rod for scoring and nicks that may tear the new seals. Minor damage is not too bad and should work well for awhile, but severe scoring should be addressed. I don't know how much your Bobcat dealer would charge for a new rod, if needed, but a good hydraulic shop could probably build you one cheaper. Use care during reassembly with the new o-rings and lubricate well. Keep everything clean, any dirt or metal pieces will end up in your hydraulic system. If you plan on changing your hydraulic filter after repairs, it is best to test everything first in case you have to tear it apart again to fix a leak.
I don't have any experience with Bobcat axle seals, so I'll leave that for someone else.
I also have an M600 and I'm looking to replace the seals as well. Can anybody tell me what size spanner wrench is needed before I go and buy the wrong one?
 

buckwill

Member
Joined
Dec 19, 2019
Messages
23
I also have an M600 and I'm looking to replace the seals as well. Can anybody tell me what size spanner wrench is needed before I go and buy the wrong one?
ii would sugges anyone doing their own repairs on these or any other machine should invest in one of the inexpensive electronic digital harbor freight digital caliper in at least 6 inches, and a decimal to fractions wall chart, the wall charts almost allways also show in metric, get the digital not the mechanical, one little grain of sand or a chip in the gear rack and that browne and sharp/starrett caliper is useless, and almost impossible to clean, they cost only about 12 to 15 dollars and dont skip or lock up, and are invaluabe for checking rod, nut, bolt, pipe sizes, buck
 
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