How to Fix Hydraulic Press: Common Problems
A press that will not hold pressure usually has a worn seal or fitting, and this guide shows how to find the failed part and match the right seal kit to the job.
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5 Pack Hydraulic Seal Installation Tool Kit9.6/10View on Amazon - 2
XBVV 420 Pcs Hydraulic O-Ring Kit for ORS/ORFS9.6/10View on Amazon - 3
OMT Bearing Press Kit, 10pc Bearing Race and Seal9.5/10View on Amazon - 4
HC5345 Seal Kit For SeaStar Hydraulic Steering9.4/10View on Amazon
A hydraulic press that will not build pressure turns a quick bearing job into a long afternoon. The ram creeps, the gauge stays flat, or fluid weeps from a fitting, and the press that used to move steel now barely moves itself. Learning how to fix hydraulic press trouble starts with finding where the pressure goes, and most of the time the answer is a worn seal, a tired O-ring, or a fitting that no longer seats.
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Below: the common failures behind a press that will not hold pressure, the checks that point at the failed part, and the seal kits and tools that handle each fix.
5 Pack Hydraulic Seal Installation Tool Kit
A 5-piece hydraulic seal installation tool kit with 3 seal twister tools for rods from 0.87 in to 6.49 in, plus a pick and hook set.
Pros
- 3 seal tools cover rods from 0.87 in to 6.49 in
- Pick and hook set included for old seals
- Color-coded sizes for quick identification
- 12-month warranty for quality-related issues
Cons
- No O-rings or seals included in the kit
- Handles rod seals only, not fitting O-rings
- No storage case is listed for the set
- 30-day money-back term is shorter than the warranty
XBVV 420 Pcs Hydraulic O-Ring Kit for ORS/ORFS
A 420-piece O-ring kit in 9 sizes from 1/4 in to 2 in, made from nitrile rubber rated NBR 70, for ORS/ORFS flat-face hydraulic fittings.
Pros
- 420 O-rings in 9 sizes, 1/4 in to 2 in
- Nitrile rubber rated NBR 70
- Rated from -40°F to 248°F
- Made for SAE J1453 ORS/ORFS fittings
Cons
- No warranty term is stated
- Only a single pick is included for removal
- Fittings only; no cylinder rod seals included
- No metric sizes are listed, only inch sizes
OMT Bearing Press Kit, 10pc Bearing Race and Seal
A 10-piece bearing race and seal driver set with 9 dual-sided adapters from 39.5 to 81 mm, a knurled driver handle, and a storage case.
Pros
- 9 dual-sided adapters cover 39.5 to 81 mm
- Heavy-duty aluminum alloy, corrosion-resistant coating
- Knurled handle and laser-engraved size marks
- 1 year warranty stated
Cons
- Made for bearing races and seals, not cylinder seals
- No O-rings or seals included
- No case dimensions are stated
HC5345 Seal Kit For SeaStar Hydraulic Steering
A seal kit for SeaStar hydraulic steering cylinders with a pin wrench, a seal gland assembly guide tool, 2 seal glands and black rings, made from aluminum, steel and rubber.
Pros
- Pin wrench and gland guide tool included
- Fits HC5340 through HC5345, HC6750 and HC6751
- Aluminum, steel and rubber construction
- 2 seal glands and rings for a full gland rebuild
Cons
- No warranty term is stated
- Made for SeaStar steering cylinders, not shop presses
- Title names fewer models than the bullets list
How to Fix Hydraulic Press: Find Where the Pressure Goes
A press builds pressure when the pump forces fluid into the cylinder and pushes it against the ram. When pressure will not build, fluid is escaping somewhere. Start with the fittings, because a fitting leak leaves a film of fluid on the hose end and the fitting body, and a flattened O-ring is the usual cause. Wipe each fitting dry, work the handle, and watch for fresh fluid at the threads and the hose crimp.
Next, watch the ram. A ram that creeps down under load points at the cylinder seal, which lets fluid slip past the piston and back to the low-pressure side. A ram that moves slowly in both directions can mean the same thing, or air trapped in the cylinder after a seal change. Check the fluid level in the reservoir before ordering parts, because low fluid lets the pump draw air, and air in the lines feels like a weak press even when every seal is sound.
Common Problems and What Causes Them
Fluid weeps from a fitting. The O-ring at that fitting has flattened, cut, or hardened with heat and age. A fitting tightened past its seat can cut the ring on the first install.
The ram creeps down under load. The piston seal inside the cylinder is worn and lets fluid pass. The press still moves, but it will not hold a load.
The ram moves slowly or not at all. A worn seal lets fluid slip past the piston, so pressure never builds enough to move the ram at full speed, and air in the system adds a spongy feel. Fix the seal first and bleed the cylinder after, the way the press manual describes.
The press will not build pressure at all. A blown seal, a cracked fitting, or a pump that draws air will all leave the gauge flat. Work from the outside in: fittings, then cylinder seals, then the pump.
Check the Seals and Fittings Before Ordering Parts
Match the part to the fitting or the rod it serves. The O-ring kit below holds 420 rings in 9 sizes, from 1/4 in to 2 in, for ORS/ORFS flat-face fittings, so measure the fitting and pick the ring that matches its size rather than guessing from the hose. The seal install tool covers rods from 0.87 in to 6.49 in, with gland holes from 22 to 165 mm, and the bearing driver set spans 39.5 to 81 mm. Check the warranty term before ordering: the seal install tool states a 12-month warranty and a 30-day money-back term, and the bearing driver set states a 1 year warranty, while the O-ring kit and the steering seal kit state no warranty term.
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The Gear That Handles Each Fix
Each check above points at a seal, a fitting, or a driver, and the kits below cover that work: O-rings for fittings, a seal tool for rods, a driver set for races and seals, and a seal kit for steering cylinders.
FAQ: garage tools
Why does my hydraulic press leak fluid?
The usual cause is a worn O-ring at a fitting or a worn seal in the cylinder. The O-ring kit below holds 420 rings in 9 sizes, from 1/4 in to 2 in, for ORS/ORFS fittings, so match the ring size and fit a fresh ring.
Why will my hydraulic press not build pressure?
Fluid is escaping past a seal or a fitting, or the pump is drawing air from a low reservoir. Check the fittings for fresh fluid, check the reservoir level against the manual, and look at the cylinder seal if the fittings are dry.
Why does the ram creep down under load?
The piston seal is worn and lets fluid slip past the piston, so the cylinder needs a fresh seal matched to the rod size; the seal tool below covers rods from 0.87 in to 6.49 in.
What size O-ring does a hydraulic fitting need?
Match the ring to the fitting size, not the hose. The kit below covers 9 sizes from 1/4 in to 2 in, and the old ring gives the size when the fitting size is not marked.
Can I replace a hydraulic cylinder seal myself?
Yes, with the right tool for the rod size. The seal install kit below holds 3 seal tools and 2 picks, covers rods from 0.87 in to 6.49 in, and states a 12-month warranty. Follow the press manual for the bleed step after the seal is fitted.
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