When a two-tonne excavator boom cylinder arrives at our Sharjah workshop on a flatbed, the client usually asks two questions: “Can you save it?” and “What exactly will you do to it?”
The first answer is almost always yes — heavy duty cylinders are built to be rebuilt, and a proper overhaul restores them to OEM performance at a fraction of replacement cost. The second question deserves a real answer too, because “overhaul” means very different things at different workshops. Some shops swap seals, wipe the rod down, and call it overhauled. That’s a reseal, not an overhaul — and it’s why the same cylinder comes back leaking six months later.
Here’s what a genuine heavy duty cylinder overhaul involves, step by step, exactly as we do it at ASAT.
Step 1: Arrival Inspection and Documentation
Before a single bolt is touched, the cylinder is externally inspected and photographed. We record the machine it came from, visible damage, leak points, and rod condition. Ports are capped during transport — an open port lets sand in, and in the UAE, sand finds everything.
Why this matters to you: documented arrival condition means an honest quote based on evidence, not a workshop’s guess — and no surprise charges later.
Step 2: Controlled Disassembly
Heavy duty cylinders hold stored energy and heavy components. The gland is broken loose with proper spanner tooling (never pipe wrenches — they crush glands), the rod assembly is drawn out with lifting support, and every component is laid out in sequence: gland, head bush, piston, piston seals, rod seal, wiper, O-rings.
The old hydraulic oil that drains out gets inspected too. Metallic glitter in the oil means internal wear; burnt smell means the system ran hot. The oil tells us about the machine, not just the cylinder — and we tell you what we find, because fixing the cylinder without fixing a contaminated system just schedules the next failure.
Step 3: Measurement Against OEM Specification
This is the step that separates overhaul from reseal. Every wear surface is measured:
- Barrel bore — checked with a bore gauge for wear, ovality, and taper along the full stroke length
- Piston rod — diameter, straightness on rollers, and chrome condition
- Head bush clearance — rod-to-bush fit against spec (a worn bush is one of the most common hidden causes of repeat seal failure — we covered this in detail in our head bush guide)
- Piston and seal grooves — for wear, scoring, and damaged lands
Nothing is judged by eye. A barrel can look fine and be 0.2 mm oval — enough to bypass any piston seal made.
Step 4: Barrel Honing
Light scoring, polishing marks, and minor ovality in the barrel are corrected by honing — machining the bore back to a uniform, correctly finished surface. The crosshatch finish left by honing isn’t cosmetic: it holds the oil film that piston seals need to survive.
If the barrel is scored too deep to hone within tolerance, we say so, and we quote the options honestly: sleeve, re-tube, or replace. An overhauled cylinder with a bad barrel is money wasted, and we won’t build one.
Step 5: Rod Repair — Straightening, Grinding, and Re-Chroming
The piston rod takes the worst abuse on heavy equipment. Depending on its condition:
- Bent rods are straightened on a hydraulic press, checked on rollers to fine tolerance
- Worn or scratched chrome is ground off, and the rod is re-chromed with hard chrome plating, then finish-ground and polished back to exact original diameter
- Deep damage may call for a new rod, machined in-house on our lathes when OEM parts are unavailable or slow to import
A properly re-chromed rod is not a compromise — hard chrome restored to spec performs like new, and the surface finish is what determines how long your new rod seals last.
Step 6: New Seals — The Full Kit, Correct Material
Every soft part is replaced: piston seals, rod seal, wiper, wear rings, O-rings, and backup rings. Never reused, never “still looks okay.”
Material choice matters in this climate. Standard NBR seals are rated to around 100°C; on machines working through UAE summers, cylinder temperatures can push past what NBR tolerates long-term. Where the duty cycle demands it, we fit higher-temperature seal compounds — it costs slightly more and lasts significantly longer in local conditions.
Step 7: Assembly and Head Bush Replacement
Reassembly happens in a clean area — contamination during assembly is a silent killer of fresh overhauls. If measurement showed bush wear, a new head bush is fitted (machined in-house when needed) so the rod runs true and the new seals aren’t destroyed by misalignment.
Torque values on the gland and piston nut are set to specification. An over-torqued piston nut distorts seal grooves; an under-torqued one eventually lets the piston spin loose — both are failures we’ve repaired from other workshops’ rebuilds.
Step 8: OEM Pressure Testing — Before It Leaves, Every Time
The finished cylinder goes on the test bench and is cycled under pressure to OEM specification. We check:
- Static hold — pressurized and held to detect internal bypass (drift)
- Full-stroke cycling — smooth movement, no stick-slip, no jerking
- External leakage — dry gland, dry ports, dry welds
- Rod drift under load — the test that catches internal leakage a visual check never will
Only after passing does the cylinder get capped, rust-protected, and released. That test is the difference between “we think it’s fixed” and “we proved it’s fixed.”
How Long Does a Heavy Duty Cylinder Overhaul Take?
For a standard heavy duty cylinder with rod re-chroming: typically 3–5 working days, mostly driven by the chroming process. A reseal-plus-honing job without chrome work can often turn around in 24–48 hours. Emergency cases: call us — with same-day pickup across Sharjah Industrial Areas 1–17 and Al-Sajaa, and mobile teams across all Emirates, we prioritize machines that are holding up a project.
Overhaul vs Buying New: The Honest Math
A full overhaul typically costs 30–50% of a new OEM cylinder — and for older machines, the OEM part may take 6–12 weeks to import, if it’s available at all. The overhaul makes sense when the barrel and rod are recoverable, which they are in the large majority of cylinders we see. When they’re not, we’ll tell you before you spend a dirham, and we can quote custom manufacturing to your exact specifications instead.
Got a heavy duty cylinder down? Bring it to our Sharjah Industrial Area 13 workshop or call (+971) 521 789 550 for pickup — free diagnosis, honest assessment, and OEM-tested results. Learn more about our complete hydraulic cylinder repair and overhaul services in UAE
FAQ
Q: What is included in a heavy duty hydraulic cylinder overhaul?
A full overhaul includes complete disassembly, measurement of all components against OEM specification, barrel honing, rod straightening and re-chroming where needed, head bush replacement, a complete new seal kit, clean-room reassembly to correct torque values, and pressure testing to OEM specification before return.
Q: How long does a hydraulic cylinder overhaul take in the UAE?
At ASAT’s Sharjah workshop, a standard overhaul with rod re-chroming takes 3–5 working days. Reseal and honing jobs without chrome work can be completed in 24–48 hours, and emergency cases are prioritized with same-day pickup across Sharjah’s industrial areas.
Q: Is it cheaper to overhaul a hydraulic cylinder or buy a new one?
An overhaul typically costs 30–50% of a new OEM cylinder and avoids import lead times of 6–12 weeks on many parts. Overhaul is the right choice whenever the barrel and rod are recoverable, which is true for most heavy duty cylinders.
Q: What is the difference between a cylinder reseal and an overhaul?
A reseal replaces only the soft seals. An overhaul measures every component against OEM tolerances and corrects the underlying wear — honing the barrel, re-chroming the rod, replacing the head bush — so the new seals actually last. Reseals fitted into worn cylinders commonly fail within months.