Hydraulic Stop Leak

235 works on the hydraulics of:

• O-rings: 235 brings flexibility back to the O-ring material, for a tighter fit that prevents leakage.
• Rod seals: it restores them to tolerance and "un-gums" frozen garter springs, for a tighter fit.
• Wear rings: it helps return the seal to specification, which reduces shaft wear and keeps costly shaft and ram replacement to a minimum.

Wiper seals

Wiper, or scraper, seals are a hydraulic system's first line of defence, keeping dirt, mud, water and other contaminants out. On heavy equipment the cylinder rods are constantly exposed to dirt and the elements. When the scraper is dried and hard, the rod gets coated with excess oil and dirt, which builds up, makes the surface uneven and abrasive, and wears the cylinder seals down until contaminants get into the system.

Once inside, the particles act as a lapping compound, wearing down valves and pumps. Contamination particles are the most common reason for hydraulic breakdowns and short seal life, and premature system failure is often due to particulate and moisture contamination through worn cylinder seals.

235 rejuvenates dried and hardened wipers so they return to size, preventing further contamination.

A broken or cracked seal normally leaks profusely, while a worn, hardened or dried seal just leaves irritating puddles of oil each day. If the equipment isn't losing vast amounts of oil, try 235 as a first step, before spending big money on mechanical repairs and new seals: hydraulic system repairs range upwards from $300 to $3,000, and even higher. 235 has a long history of successfully repairing slow oil leaks in hydraulics.

It works on these kinds of seal wear

Gradually increasing leakage, characterised by:

• Progressive wear and drying
• Increasing compression
• Progressive tear or erosion from an initial nick
• A fine score mark on the dynamic surface

Slow, uniform leakage, characterised by:

• Poor low-pressure sealing
• Too little initial interference
• Loss of interference or squeeze through wear or compression set
• Seal shrinkage after installation
• Microscopic debris lodged under the seal lip
• A lip scored by a sharp particle passing under the seal, leaving a cut or nick
• A seal lip nicked or cut during installation (note whether the leak started straight after the seal was fitted)
• Non-repetitive overheating that has hardened the compound, so it can no longer conform to deviations in the dynamic surface
• Off-centre alignment that puts all the clearance on one side and all the compression on the other, from bearing wear, excessive side loads and the like

Erratic, stop-start leakage, characterised by:

• Cold start-ups
• Intermittent eccentric loading
• Fibrous contamination working its way past the seal lips
• An unstable seal that twists and returns or cocks, usually from shock loading
• A rod seal leaking slowly, with a tight wiper periodically dumping the oil that has built up
• Fluid viscosity changing as the temperature cycles, such as a forklift going in and out of a cold store

It won't work on sudden, copious leakage

235 can't improve a seal with mechanical damage: one that is cracked, ripped or torn. Sudden, copious leakage is characterised by:

• An extruded seal
• A torn seal lip
• A twisted seal
• Dramatic bearing failure from excessive side load, shock and the like
• Spiral failure
• A massive infusion of contamination, from the wrong fluid added to the system or dirt or wear debris introduced upstream
• Reverse-pressure blowout of a piston seal, from a pressure trap or failure of the opposed seal

It may be a false alarm. Slow rod seal leakage can build up behind a tight wiper and then dump all at once, which looks like a catastrophic seal failure. If the leak rate then drops, look for the slow or erratic causes above. If the high leak rate continues, look for a true catastrophic leak.