How to unstick a track tensioner?

[bdcz]

Any advice on getting a frozen hydraulic track tensioner to move? I rebuilt these tensioners about 100 hours ago so their in good shape but one of them is stuck. I can't generate enough pressure with a grease gun to move it. It used to move easy but after re-bushing track I haven't had to adjust them in about 3 years and now it's stuck. Any tricks to avoid taking the track off? This is on a JD350.

[Tigerhaze]

Is the tensioner stuck in the fully retracted position? If not, then you should be able to remove the bolt that lets grease out (don't know the actual part name for it) and then push the adjuster inward using another piece of machinery or by pushing it against an unmoveable object against the front idler. Also, if a dozer I have heard you can wedge something between the blade and the front idler to do the same thing, using the hydraulics of the blade.

It seems that it would then be unstuck enough to pump up using the grease gun. If all the way retracted, not sure what you could try. Just some ideas to try.

[bdcz]

Thanks for the suggestions Tiger. I did try loosening the bleed plug and driving the idler against a tree stump. That didn't work because it just compressed the spring. In order for this to work the spring would either need to be compressed until it is solid or I would have to shim the spring coils so that it would act like it was solid. That was going to be the next thing to try. I didn't want to keep pushing against a tree with the spring compressing because it looked like the track might come off if I kept going. I was hoping to find a way to do this without having to drive up against an immovable object. I've also tried whacking the tensioner from side to side with a sledge hammer. I was hoping this would jar it enough to break it loose. No dice. I wonder if heating up the tensioner housing would help? Any other ideas?

[digitup2]

If you heat the housing you will damage the seal so try this .Pump the adjuster up a bit tighter then .take the relief screw out and seal ball if equipped also take the grease fitting out and through a greasy rag over it the main housing and give it a god running see if it comes back any further .I have had two of the 21B Allis's seize up and I have a high pressure grease gun to pump them up and use a 120 B Deere excavator to back them off by driving up behind and touching the tracks then catch a grouser just before the top of the front idler with a tooth and pull like crazy with the relief screw removed .I guess you could do the smaller machine with a backhoe but they will loosen up quickly that way.Digitup.

[bdcz]

Thanks Digitup2, I don't have any heavier machinery to push or pull on it so I think I'll try shimming the spring up solid and driving up against a tree stump. Only think I can think of right now.

[coehillbilly]

Hello All..one of my tracks came off and I have the same seized problem on the adjuster. I removed the grease nipple and used the bucket on the loader to try and push the adjuster back toward the spring...very little grease did come out and it only went back about an inch and then sprung forward a 1/2 inch when I released the bucket. Further inspection of the cylinder housing revealed that the housing was previously changed and that it must have come from an earlier model as it only had one hole in the casting where the nipple went in...there was no other relief screw on it as the parts diag for the 350B showed. My guess is it did not fit properly when changed but worked for awhile then seized. So what to do now I guess would be to install another housing if I can ever get the old one off. I did manage to get the track back on with the help of heavy forcible equipment and when I inserted grease back in the housing to try to readjust the cylinder it never moved but grease oozed out the bottom through the casting.

[bdcz]

Wish you luck Coehill. My parts are regular JD350 design but still got stuck. I haven't had time to work on mine lately but I'll let you all know if I figure out a way to get it unstuck.

[Lavoy]

I have found that often they will not collapse, but will extend. Take the adjuster out of the crawler all together, and see if you can pump it all the way out with grease. Then you can clean all the rust off of the rod, and you can hone the battel with a regular cylinder hone. If the seal is leaking, this may not work.
Lavoy

[mini kahuna]

Lavoy is right,I have gotten a couple adjusters to extend themselves apart,honed out the barrel,new cup seal and back together.
the ones I had stuck were because of using grease that hardened up solid,I have been using syn/blend grease for years now on everything and haven't had any problems since.
I also resorted to boiling one in water and after a half hour or so it loosened up and came apart.

[jd455Djc]

We used a pair of 8 ton hydraulic jacks on the 455D, wedged against the arm and the frame. Had to use piece of metal to get a good seat for the pump, laying horizontal.

Pumped each jack until very tight with pressure, then pumped grease up to bypass in grease gun. Tightened each jack again and repeat.

We removed the front idler and track tensioner as a single unit. Took seals to local Allied Seal and came home with a pair for each side for $30 total.

Putting it back together was its own challenge...

- JC

[coehillbilly]

Thank you for all the ideas and tips, before I purchased this it was not used much for a few years.

[bdcz]

I still haven't got mine unstuck yet. I was going to fill the spring with metal spacer bars so that it would go solid when I push on the front idler. But I can't find enough steel of the right thickness laying around my place to do the job. I'm also concerned that if I just drive into something solid I might break the edges off my idler wheels. So, I'm thinking that this spring I might try a more reliable source of hydraulic pressure than my grease gun. Has anyone ever tried hooking up to a high pressure hydraulic source and giving the tensioner a shot of 2500 psi hydraulics? I was thinking I'd just hook up the pressure side of my farm tractor loader hydraulics using the appropriate adaptor fittings and then see if that would move the adjuster. I suppose I could also just use the dozer's blade hydraulics to do the same. I'm not sure how much pressure the adjuster housing is designed to take before it would crack however. Anyone ever tried this?

[coehillbilly]

I would think that high a pressure would certainly blow the seals and create more problems for you...a thought and a question...how about injecting a grease thinner of some sort to try and dissolve the old hardened grease if that might be the problem??

[bdcz]

I don't think the grease is hard. I just put fresh in a couple of years ago and when I bleed the adjuster on the opposite side the grease comes out nice and smooth. I think the thing is rusted. I did some checking, a common long handled grease gun is supposed to put out 3000 to 5000 psi depending on the gun. I even found some high pressure ones that are supposed to put out 15,000 psi. I don't know what mine puts out but it is a standard full size gun with about a foot long handle. Just doing the math it should put out 2000 psi or more. So I doubt if hooking up a 2500 psi hydraulic source is going to hurt anything but it also may not help anything either. I modified the original seals in my machine when I rebuilt the adjusters. I put in a very heavy urathane U cup seal that will definitely not blow out even at thousands of psi. I thought about your idea to put some solvent in there just to make the grease runny in hopes that it would leak past the seals and free the thing up. But how does one get anything in there when you have to move it to get anything in or out? On the off chance that my grease gun is under powered I may still try some hydraulic pressure. I just don't want to take the track off since it's a major pain.

[KenP]

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