The Stovebolt Site Forums The Parking Lot Big Bolts Hydraulic Cylinder Seal

The hydraulic cylinder for my dump is leaking out of the seal where the piston extends out. I don't see an obvious way to split the cylinder to get to the seal. Is the replacement of this seal a backyard mechanic job or not.

See pics.
http://rides.webshots.com/album/579922456jFVpcI

It looks like that cylinder end is threaded in. It would take a spanner wrench that can grab those projections on the end cap to get it loose. Good luck finding a seal once you get it apart!
Jerry

Edit: If fluid is getting to that side of the piston, the piston packing is also leaking. There should be little, if any fluid up there. The "seal" around the shaft is probably nothing more than a dust wiper.
Jerry

I prefer a chain wrench that can wrap around the cylinder head but whatever method you use don't worry about finding a seal. They are available in almost any size as are O rings which I doubt it has but. The piston seals are likely cast iron piston rings but can be replaced by floating seals too. They probably are not the culprit however.

If you think this one is tough be glad it isn't a cylinder with a weld head. Now those can be fun. Think lathe.

Thanks for the info. I tapped on the cap lightly with a hammer and it started moving a bit so I don't think I'll have a problem getting it apart. I went to work on pulling the cylinder, got it out started to carry it outside to clean and threw my back out, bad. Can hardly move. I guess I'll sit and watch the NCAA tourney and see my bracket go up in flames.

Get that situation checked out- - - -soon! Back problems aren't something to take lightly. Next time, get a helper to share the load!
Jerry

those trucks are cool.So are Chiropractors.

goneagain - I got the truck about a year ago in Vay Idaho. Never heard of it prior to getting the truck. Has to be somewhere around you since N. Idaho isn't that big.

Jrpontiac I didn't notice that we are neighbors. I'm in Hauser Id.I had to google Vay.There are lots of hydraulic shops in Spokane.

Actually there is suppose to be oil on that side of the piston because that side of the cylinder also serves as the hydraulic reservoir.

When I replaced the seal on my '48 the one that came out was a leather lip type. The one I put back in was the modern double lip rubber type. And if I remember correctly there is enough room to put two of them in there, which I did so the outer one acts as a dust shield and better protects the inner one.

I also used a type of teflon rope that I wrapped around the flanged face of the cap to seal it to the cylinder when threaded back on.

What I find especially ingenious about this type of set up is that the outlet hole on the reservoir side of the cylinder also serves as the bypass. As the piston moves up the cylinder while lifting to the top past this hole, the pressure escapes though this hole and recirculates back to the pump. Pretty cool I thought.

Anyways, I hope your back feels better soon and back to working on your truck!!!

Paul.

Back feels much better today. I got out today and got the cylinder apart. Came part pretty easy. The seal/dust seal that you see is the only seal there is. The interior piston has no o rings, they look like giant engine piston rings. There are 3 grooves with 2 rings in each groove. I guess I don't have to worry about the main piston being absolutely sealed because the resevoir is on the low pressure side.

OOPS! I forgot about the top side acting as the reservoir! Most single-acting cylinders have a vent with some type of air filter on the dry side.
Jerry

Paul,
I picked up 2 seals like you suggested, great idea. Did you install them both facing the same way? Or did you install the outward seal reversed?

Jason

Hi Jason, I installed them both facing the same way. Also be sure to check where the old seal was in contact with the shaft when all the way down. Sometimes there can be a wear spot on the shaft that will cause the new seal to leak. Usually emery cloth will buff that wear spot out.

Also, another set of hands would be nice putting the piston back in the cylinder, it's kind of a bear by yourself.

It's sure nice when fixed not to have it leaking all over the differential, so it's certainly worth the effort.

Good luck, hope to see some pics.

Paul.