Hydraulic Cylinder Blow By

farmallboy15 · Oct 14, 2021

On my sickle bar, the single acting lift cylinder has a fair amount of blow-by when lifting. Blue in the picture is where the hose is hooked into. Red is the breather hole where fluid comes out towards the top of the stroke. I ended up putting in a new packing kit. I didn't notice any damage to the rod, piston or cylinder bore but assume the bore is worn somewhere in the stroke. Should I replace just the cylinder case or the whole assembly ($450 vs $150).

Steve@Advance · Oct 14, 2021

I would take it apart and have a look.

Many times, especially with urethane seals, they die of old age, nothing to do with the condition of the cylinder.

Unless there is an obvious problem, nothing to loose by just sealing it and see how long it will last.

wore out · Oct 14, 2021

It's possible the barrel has some rust putting. A hydraulic specialty shop MAY be able to hone it if the pits or other surface damage is not severe. Also, they MAY be able to supply an aftermarket HD sealing ring that is better/tougher than the OEM for use in a less than perfect bore. A good shop should be able to make up a new barrel, if needed, but @ the price you posted that probably wouldn't be a money saver.

cool hand · Oct 14, 2021

I had such a leak on my dump trailer, I simply installed a hose from the leaking port back to the reservoir recapturing all of the oil that by-passes the piston.

farmallboy15 · Oct 14, 2021

Already took the cheap route and tore it apart and put new seals in. The old ones were a little hard but didnt notice any damage to any of the components, seals or hard parts although its hard to clearly see the condition of the bore all the way to the end..,

Steve@Advance · Oct 14, 2021

Sorry, I didn't read the post carefully.

Did you take the piston off the rod? There's usually an oring there that seals the connection.

farmallboy15 · Oct 14, 2021

I did and yep, got that one. New seals slowed down the leak a little bit still too much to live with. Itll squirt out a half cup at the top of the stroke

tom upton · Oct 14, 2021

Is there a chance you put piston seals on backwards? I noticed pressure side is the rod end, so you are retracting cylinder to lift. If using any type of vee seal on piston the open side where pressure would push seal tighter to cylinder has to be facing towards the pressure side. Not sure if I explained that right but hopefully you will know what I mean.

SVcummins · Oct 15, 2021

Any reason you cant replace the cylinder with a generic one off the shelf at tsc Bomgaars or other farm and home store fir about 150 dollars

SVcummins · Oct 15, 2021

Not a terrible idea especially considering the application

Hydraulic Cylinder Blow By

farmallboy15

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Steve@Advance

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wore out

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cool hand

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farmallboy15

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Steve@Advance

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farmallboy15

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tom upton

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SVcummins

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SVcummins

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