Repairing Hydraulic Piston Shaft Gouge - Possible?

[Jay4200]

More bad stuff uncovered - I don't know how I missed this one...I was sure I checked all of the shafts...

I found a couple of significant gouges in one of the stabilizer pistons on my backhoe. It looks like a boulder fell off of the bucket and landed on the piston shaft (downside of a 180 degree backhoe swing - keep that in mind). There are two substantial gouges - each an inch or two long. One is maybe a quarter inch wide, the other an eighth. The smaller of the two is right at the end of the piston, so while it goes inside the cylinder, I don't think it passes the oil seal. The other is mid-shaft and carries a small bloop of fluid inside it - and I suppose probably can carry dirt back inside...wonderful. Neither appear to have sharp edges, however, at least the seal does not appear to have been damaged - it is not leaking.

I'm wondering if there is anything I can use to fill the gouges to reduce the chance of damaging the cylinder seal - maybe something like JB weld? I'm thinking I could rough up and undercut the gouges with a dremel tool, fill it, then sand and buff it smooth. What do you think? I figure anything would be an improvement - as long as the filler doesn't pop out inside the cylinder. Any other suggestions?

Thanks - Jay

 

[tillerkiller]

I have heard of JB Weld being used for just this purpose. If you undercut it so that the JB Weld can't get out I _think_ you will be OK. If the gouge is not very deep then I would just file it out, but I get the idea that it must be pretty deep. You are 100% correct that any sharp edge is a bad thing.

Find out where your hydraulic filter is located, if it is on the return line then even if the JB Weld got out of the gouge it would get caught by the filter before it could get ingested by the pump (hydraulic pumps do not like solid objects.)

 

[Soundguy]

Fill with braze.. then take a flat file to it.. check frequently with a straight edge to see contour.. then finish with a superfine / ultra fine stone or hone..

We've repaired a few multi-thousand dollar backhow pistons this way... It works fine as long as the piston isn't bent -any-

Soundguy

 

[Jay4200]

Thanks guys - and yes, the gouges are too deep to file out. I like the braze idea - I was thinking about doing something similar with solder, but brazing is better and I suppose is basically the same thing. I, however, have absolutely no experience with brazing. I would think it would be hard to heat up a big shaft like that enough to braze w/o screwing up the steel temper/chrome (are these things made out of chromed steel?), but maybe not - I've never done anything like that before. Any specific helpful hints you can share about brazing something like this?

Thanks - Jay

 

[Soundguy]

If you are more comfortable with solder.. go for it.. i'd use silver solder and a good paste flux.. key is to fill the void.. then file to contour.. the 'filler' won't be under much load that will hurt soft metal..

soundguy

 

[JustGary]

Hard silver solder "silver braze" will take just about the same heat as bronze rod will. Both are probably equivalent for this job, and silver will look better. Your local Ace Hardware will have both kinds available. A NAPA dealer might have them too. I bought a pound (lifetime supply) of flux at a NAPA dealer when I was about 18. I still have over half of it left, so I'm right on schedule.

Go to your local transmission shop and ask him politely for a dead Toyota half shaft or something. He has a million of them cluttering the pile out back. Take it home and grind a nick in it (or whack one in it with a hammer) and practice brazing until you get comfortable enough to do the ram.

Note here: "Rod" is the brazing rod, and "ram" is the pitted piece you want to fix.

To braze, flux the rod (heat the rod and dip it in borax flux, or buy pre-fluxed rods), then heat the desired ram area cherry red and apply the brazing rod to the ram just at the end of the torch pencil flame. If the ram is hot enough, the rod will melt onto it. You can guide the molten braze with the flame to make it lay down and flow. It will follow the heat.

You'll see the surface tension break as the braze flows and sticks to the ram. If it doesn't flow and lay down, it didn't melt enough to stick. Don't overheat the area or you'll oxidize the braze and have to start over. I would imagine that you won't have that problem on something the size of a ram.

Brazing really is simple and fun. A little practice will have you ready to do the job.

Oh, Brownell's sells heat-blocking paste that you might put on the ram to help keep from heating the rest of it more than you need to. I've never used it, but would consider it for this job. You can probably get some at a decent welding supply house.

Good Luck!

- Just Gary

 

[hayden]

I made such a repair successfully (mostly) with JB Weld on the curl cylinder on my backhoe. It got gouged by a rock.

I didn't think it would work, but figured I had nothing to lose so I tried it. It worked 90%, and is still working 3 years later. I cleaned up the gouge, filled and smoothed with JB Weld, then finished it with emory cloth. It still leaks a tiny bit, which is why I say the repair worked 90%, but I really mean only a tiny bit. I don't consider it a problem at all.

Brazing sounds even better if you can pull it off. I think the real key it being sure whatever you use stays put.