Replacing an end seal

[BrentD]

I was out changing some fluids on our Mitsubishi BD2G dozer over the weekend and noticed that one of the cylinders for raising/lowering the blade is leaking fluid from the end of the cylinder around the rod. I'm assuming that this means a seal is shot and needs to be replaced.

How difficult of a job am I looking at? The cylinder end cap appears to be in good condition and the threads look reasonably clean, not painted over or anything so I'm hoping it should be relatively easy to get the cap off. It also looks like I should be able to do this without completely removing the cylinder from the dozer. Looks like I can just undo the pin that attaches the rod to the boom, undo the end cap and remove the rod from the cylinder and replace whatever seals need to be replaced.

Is there a special wrench to remove the end caps? Looks like it's just got two square notches in the cap so it shouldn't be too hard to make a wrench. Any idea how much torque I should expect? Anything else I need to know before I jump into this head first?

 

[Wayne County Hose]

Post pictures of the gland (end cap) and we can tell you exactly how to disassemble and rebuild.
Andy

 

[BrentD]

Here's the entire cylinder:

Viewed from the top (sort of):

Dead-on:

 

[kennyd]

That should just screw off Brent, make a spanner if you can-worst case use a pipe wrench...And to make it easier-crack it loose while it's still on the machine so you don't have to worry about holding it. It will be pretty tight!

Is this a Grey machine? Either way the seals may be a oddball size or Metric...

 

[BrentD]

Is this a Grey machine? Either way the seals may be a oddball size or Metric...

Yep. Bought it from a guy who buys them direct right off the boat from Japan. I think this particular one came in via one of the Houston/Galveston ports.

It's a 1988 model and still runs like a top. Starts within 2 seconds of the the first turn of the key every time. Never a puff of black smoke out the tail pipe and I can buy the blade up against a tree trunk or the bank of the pond I'm renovating and the tracks will break traction before the engine even hesitates. Only down side to that is it's real easy to dig yourself into a hole in a hurry.

 

[BrentD]

Ok, I need some assistance... I got the end cap off, now I have a piece with threads around the rod and then recessed back a bit is what appears to be an O-Ring. I thought once I got the end cap off that the piston would just pull right out, but that doesn't appear to be the case. What do I do now? (My service manual is in Japanese so that's not really helping.)

Edit: Ok, it's not an O-ring, there is a round metal retaining ring that has to be popped out. No idea how to go about that.

 

[J_J]

That ring is what keeps the rod assembly from coming out of the cylinder. There should be a pin hole in the side of the cylinder to push the metal ring out. You may have to push the ring so the edge of the ring is close to the pin hole. If no pin hole, there is a space in the metal ring where you can put a metal pick and lift one edge out. Cover the end with a cloth so the ring does not spring out. Be careful with the pick, so you don't make any burs that might damage the o-rings.

Here is an illustration.

http://www.patentgenius.com/image/7455010-3.html

Expanded barrel hydraulic cylinder assembly - Drawing for Patent # 7455010 - PatentGenius

http://www.patentgenius.com/image/7455010-4.html

 

[BrentD]

Thanks JJ. Got the cylinder apart, now I've got to go get a 36mm socket for my impact wrench so I can take the rod apart and get to the seals.

 

[J_J]

Don't forget to put Lock Tight on the threads of the shaft, when you reassembly the unit.

 

[BrentD]

Don't forget to put Lock Tight on the threads of the shaft, when you reassembly the unit.

Which Locktite do you recommend? Blue or Red? (or some other?)