Written by the Hydraulic & Engineering Services workshop and site services team, Strood, Kent. Hydraulic engineers since 1991, ISO 9001 certified. Last updated 20 August 2026.
TL;DR: Most hydraulic press faults come down to one of five things: worn or scored cylinder seals, a failing pump, a relief or counterbalance valve that has drifted out of adjustment, contaminated or overheated oil, or air trapped in the circuit. Diagnosis follows a fixed order. Check oil condition and level, then check pressure at the pump against pressure at the cylinder, then isolate whether the loss is internal (across the piston seal) or external (a valve or a leak). A press that has lost tonnage but holds pressure at the pump almost always has an internal cylinder leak. A press that will not build pressure at all is usually a pump or relief valve problem. Repair is worth doing when the frame, ram alignment and bed are sound, which is true of most industrial presses, because the structure is the expensive part and the hydraulics are the consumable part. Hydraulic & Engineering Services repairs, refurbishes and recommissions hydraulic presses across England, on site or at its Kent workshop. Talk to our engineers about your press.
What does hydraulic press repair actually involve?
Hydraulic press repair means restoring the hydraulic system, cylinders and controls of a press so it produces its rated tonnage safely and repeatably again. In practice it covers four separate things that often get bundled under one phrase:
- Breakdown repair. The press has stopped or lost force and needs to be back in production quickly. Usually a fault diagnosis visit followed by a targeted fix.
- Cylinder repair or overhaul. The main pressing cylinder, and often the side lift or ejection cylinders, are stripped, measured, resealed or fitted with a new rod.
- Power unit repair. The pump, motor, valves, filtration and tank are serviced or rebuilt, either in place or as a removed unit.
- Full refurbishment or reconditioning. The press is stripped, all hydraulics overhauled and tested, the frame repainted and the machine recommissioned. This is the route for an older press that is mechanically sound but tired.
The distinction matters commercially, because the first two are usually measured in days and the last one in weeks.
Why do hydraulic presses fail?
Presses do not fail randomly. They fail in patterns, and the symptom usually points straight at the subsystem. Use the table below as a first-pass diagnostic.
| Symptom | Most likely causes | What to check first |
|---|---|---|
| Press builds no pressure at all | Pump worn or failed, relief valve stuck open, coupling sheared, motor rotating the wrong way | Gauge pressure at the pump outlet; listen for pump cavitation; confirm motor rotation |
| Press builds pressure but not full tonnage | Internal leak past the piston seal, relief valve set low or drifting, worn pump slipping under load | Compare pump pressure against cylinder pressure under load; do a bypass test on the cylinder |
| Ram creeps or drifts down under load | Leaking piston seal, leaking counterbalance or pilot-operated check valve, directional valve spool leakage | Hold the load with the pump off and time the drift; isolate the cylinder from the valve |
| Ram movement is jerky or stick-slip | Air in the circuit, contaminated oil, scored bore or bent rod, worn guides | Bleed the circuit; take an oil sample; check rod straightness and surface finish |
| Oil overheating | Undersized or blocked cooler, relief valve dumping continuously, internal leakage converting flow into heat, low oil level | Tank temperature over a cycle; filter differential pressure; relief valve setting |
| External oil leak at the gland | Worn rod seal, scored or pitted chrome on the rod, damaged wiper letting contamination in | Inspect the chrome rod for scoring, corrosion and plating loss |
| Slow cycle time | Worn pump, partly blocked filter, low oil viscosity from heat, internal leakage | Time the cycle against the original spec; check filter and oil condition |
Two of those causes are worth calling out because they are so common and so often misdiagnosed.
Internal cylinder leakage. When the piston seal wears, oil crosses from the pressure side to the return side inside the cylinder. The pump still shows healthy pressure, so the gauge looks fine, but the press cannot generate force and the oil runs hot. The classic bypass test is to extend the ram fully, isolate and disconnect the return line, then pressurise. Any meaningful flow out of that port is oil passing the piston seal, and it is a cylinder job, not a pump job. Our guide to hydraulic cylinder failure causes covers the wear mechanisms behind this in more detail.
Contamination. Particulate contamination is the single biggest cause of premature hydraulic component wear, and on presses it is usually self-inflicted: a failed rod wiper drags abrasive dust into the cylinder, that debris circulates and scores the pump and valve spools, and within months you have three faults instead of one. If a press has had a rod seal failure, sample the oil before you assume the rest of the system is healthy.
My press is not building full tonnage. What is the likely cause?
If the pump reaches its set pressure but the press will not do the work, the force is being lost between the pump and the die. In descending order of likelihood:
- Piston seal bypass in the main cylinder. The most common cause on a press over about ten years old. Confirm with a bypass test before condemning anything else.
- Relief valve drift. Relief valves lose their setting over time, particularly if they have been dumping heat for years. Check the setting against the machine plate with a calibrated gauge, not the panel gauge.
- Pump wear. A worn gear or piston pump will hold pressure at no load and slip under load. Symptoms overlap with cylinder bypass, which is why you test the cylinder first, since it is the cheaper thing to eliminate.
- Wrong or degraded oil. Oil that has thinned from sustained overheating leaks internally at every clearance in the machine at once.
The important discipline is to measure rather than replace. Fitting a new pump to a press whose real fault is a leaking piston seal is a common and expensive mistake, and the press comes back a fortnight later.
Repair, refurbish or replace? A decision framework
The frame, bed, ram guides and columns of an industrial press are the expensive, slow-to-replace parts, and they are also the parts least likely to be worn out. That is why refurbishment usually beats replacement on a press when it would not on, say, a small pump.
| Breakdown repair | Full refurbishment | Replacement | |
|---|---|---|---|
| Best when | One identified fault, rest of machine sound | Machine over 15 to 20 years old, multiple worn subsystems, still structurally good | Frame cracked, bed out of parallel, tooling obsolete, or process has outgrown the tonnage |
| Typical downtime | Hours to a few days | Two to six weeks, planned | Long lead time plus installation |
| Relative cost | Lowest | Meaningful, but a fraction of new | Highest, plus installation and commissioning |
| What you get back | Working press, remaining wear elsewhere unchanged | Effectively a reset machine with new seals, rods, hoses, filtration and a fresh test certificate | New machine with modern guarding and controls |
| Compliance angle | Existing risk assessment stands | Good moment to review guarding and controls | New machine must meet current standards |
A useful test: add up what you would spend over the next three years on repeated breakdown repairs and lost production, then compare that to a single planned refurbishment. On presses that break down more than two or three times a year, the planned route almost always wins, because the cost of an unplanned stoppage in a production cell is usually a multiple of the repair itself.
If the question is narrower and only concerns the cylinders, our comparison of hydraulic cylinder repair versus replacement and the guide to reseal versus full rebuild set out how that call is made.
What does hydraulic press repair cost in the UK?
There is no honest single figure, because a reseal on one cylinder and a full strip and rebuild of a 50 tonne press are different orders of magnitude. What you can and should insist on is a structured quote:
- Fault diagnosis visit, charged as a site visit, producing a written report rather than a verbal guess.
- Strip and report, where the cylinder or power unit is dismantled and measured before anything is priced. Any supplier quoting a full rebuild before stripping the unit is guessing.
- Fixed price for the agreed work, with parts listed, so you can see whether you are paying for seals, a remanufactured rod, a new pump or all three.
The variables that move the price most are rod condition (a rod that can be reground and replated is far cheaper than a new machined rod), whether the bore needs honing, whether the power unit has to be removed, and access at your site. Ask for the report before the quote and you will avoid most of the surprises.
On site or back to the workshop?
Small faults are almost always resolved on site: valve adjustment, hose and fitting replacement, seal kits on accessible cylinders, filter and oil changes, pressure testing. Our site services team carries out this work across England, including breakdown attendance.
Larger work goes to the workshop, and that decision usually comes down to the main cylinder. Removing, stripping, honing, machining and testing a large pressing cylinder needs the bore, the machine tools and the test rig, which means a controlled environment rather than a factory floor.
A representative example from our own work: a customer’s 50 tonne press was isolated and disconnected on site by our site services division, transported to our Kent factory, craned onto skates and dismantled. All three hydraulic cylinders were removed and inspected. The main pressing cylinder needed a complete overhaul including reworking the existing rod, and the two side lift cylinders had new rods machined and were fully overhauled. Every cylinder was tested individually to a critical test procedure, refitted, then tested again with its own power unit before the press was masked, repainted, returned and recommissioned on the customer’s site. The full sequence is documented in our hydraulic press refurbishment project. That is the shape of a proper refurbishment: measured, tested twice, and handed back commissioned rather than delivered on a pallet.
Do hydraulic presses need a PUWER thorough examination?
This is one of the most commonly misunderstood points in UK press maintenance, and it is worth stating plainly.
The statutory power press regime in the Provision and Use of Work Equipment Regulations 1998 (PUWER), regulations 32 to 35, applies to a “power press”, which regulation 32 defines as a press or press brake for working metal by means of tools, or for die proving, which is power driven and which embodies a flywheel and clutch. A hydraulic press has neither a flywheel nor a clutch, so it falls outside that specific regime and does not require the six or twelve monthly thorough examination and test that a mechanical power press does under regulation 33.
That is not the same as being unregulated. A hydraulic press remains work equipment, so the general PUWER duties still apply in full: regulation 4 (suitability), regulation 5 (maintained in efficient working order and good repair), regulation 6 (inspection at suitable intervals by a competent person, with a record kept) and regulation 11 (guarding against dangerous parts). In practice most operators run a planned inspection and maintenance regime on hydraulic presses under regulation 6, at an interval justified by their own risk assessment.
On the machine safety side, hydraulic presses were covered by BS EN 693 (Machine tools. Safety. Hydraulic presses), most recently BS EN 693:2001+A2:2011, which has since been superseded by BS EN ISO 16092-3:2018. If you are refurbishing an older press, that is the right moment to review the guarding and control system against current standards, because retrofitting guarding is far cheaper while the machine is already stripped.
How to reduce press downtime before the next failure
Five things that consistently pay for themselves on presses:
- Sample the oil, do not just look at it. Particle counting picks up wear months before a symptom appears. Dark oil is a late signal.
- Treat the rod wiper as a critical part. A failed wiper is the entry point for the contamination that then destroys the pump and valves.
- Log cycle times and running temperature. A press that is 15 percent slower and 10 degrees hotter than last year is telling you the pump or the seals are on the way out.
- Keep the filtration honest. Change elements on differential pressure or hours, not when someone remembers.
- Hold seal kits and a spare relief valve for critical presses. Sourcing seals is often the longest part of a breakdown repair, not the labour.
Talk to a hydraulic press specialist
Hydraulic & Engineering Services has been repairing, refurbishing and manufacturing hydraulic equipment since 1991 from its facility on the Medway City Estate in Strood, Kent. The workshop runs an ISO 9001 certified quality system and a full machine shop, and it can handle cylinders up to 10 metres long, 0.8 metres in diameter and over 4 tonnes in weight, which covers the main pressing cylinder on almost any industrial press. Alongside in-house cylinder manufacture and repair and power unit build and repair, a mobile site services division covers England for breakdown attendance, removal and recommissioning. If a press is down, losing tonnage or simply overdue a proper overhaul, send us the symptoms and the machine plate details and we will tell you what we think it is before we quote.
Book a hydraulic press repair or fault diagnosis visit, or contact the workshop directly.
Frequently asked questions
Why is my hydraulic press not building full pressure?
If the pump reaches its set pressure but the press will not produce full tonnage, the force is being lost inside the machine. The most common cause is a worn piston seal in the main cylinder allowing oil to bypass internally, followed by a relief valve that has drifted below its setting and then pump wear. Confirm the cylinder with a bypass test before replacing the pump.
Why does my hydraulic press ram drift down under load?
Ram drift is caused by oil escaping the holding circuit. The usual culprits are a leaking piston seal in the cylinder, a leaking counterbalance or pilot-operated check valve, or spool leakage in the directional control valve. Isolating the cylinder from the valve block and repeating the test tells you which side the leak is on.
Is it cheaper to repair or replace a hydraulic press?
Repair or refurbishment is usually far cheaper, because the frame, bed and ram guides are the expensive parts and they rarely wear out. Replacement makes sense when the frame is cracked, the bed is out of parallel, the tooling is obsolete or the process now needs more tonnage than the press can deliver.
Do hydraulic presses need a PUWER thorough examination?
Not under the statutory power press rules. PUWER regulation 32 defines a power press as one that embodies a flywheel and clutch, which a hydraulic press does not have, so regulations 32 to 35 do not apply. Hydraulic presses are still work equipment and must be maintained under regulation 5 and inspected at suitable intervals by a competent person under regulation 6.
How long does a hydraulic press repair take?
A diagnosed breakdown repair on site is typically hours to a few days, depending on seal and part availability. A full workshop refurbishment involving removal, transport, cylinder overhaul, testing, repainting and recommissioning is normally two to six weeks and should be planned around a shutdown.
Can a scored hydraulic press cylinder rod be repaired?
Often, yes. A rod with light scoring or plating loss can be reground and hard chrome replated back to size, which is considerably cheaper than a new rod. A rod that is bent, deeply scored or undersized beyond regrind limits is replaced with a newly machined rod, which is standard work in a cylinder workshop.
Do you repair press brakes as well as hydraulic presses?
The hydraulic principles are the same, and hydraulic press brake cylinders, power units and valve circuits are repaired in the same way. Note that a press brake with a flywheel and clutch is a power press in PUWER terms and carries the additional statutory examination duties.