Marine & compact industrial · Sharjah
Yanmar marine and industrial engine repair
Yanmar engines reach us from two quite different worlds — ships' auxiliary and propulsion engines, and compact industrial engines in plant and small generating sets. The honest answer on what is worth repairing is different at each end.
Where the money is wasted
Two Yanmars, two completely different decisions
Yanmar builds diesel engines across an unusually wide span, and where your engine sits in that span decides the economics before anyone opens a spanner. It is worth being blunt about it.
At the small end
Compact industrial and small marine
- Multi-cylinder industrial engines under compact excavators, small gensets, lighting towers, welders and pump sets
- Small marine auxiliaries in launches and pleasure craft
- Here the calculation genuinely changes. A complete replacement unit can be close enough in cost to a full component overhaul that machining the old one is not sensible
- We will say so rather than take the work
- Very small components we decline outright — better heard on the phone than after transporting an engine
At the large end
Ships' auxiliary and propulsion engines
- Medium-speed and high-speed marine engines driving generating sets and propulsion aboard commercial vessels
- The heavier engines in tugs, barges and workboats
- Replaceable liners, individual cylinder heads, serviceable running gear, fuel equipment designed to be overhauled
- Repair is nearly always the right answer — replacement units are long-lead imports
- The machining that keeps them alive is exactly what a workshop with its own machine shop exists to do
It is done against your specific engine, its condition, and what a replacement actually costs and takes to arrive. Ask for it before you commit to anything — you will get a straight answer, including the answer that says do not repair this. We hold no brand dealership and are not a Yanmar distributor, so there is nothing in it for us either way except being right.
Identification
The Yanmar families we see
Send the engine model and serial number from the plate, and a photograph of it. On this make the plate is the only reliable identification — the same external shape covers several builds, and the builds do not share parts.
Commercial marine auxiliary and propulsion
- The medium-speed engines that drive ships' generating sets
- The high-speed marine engines in commercial craft
- They arrive as complete engines, as running gear, or — most often — as components landed from a vessel alongside
Smaller commercial and leisure craft
- Multi-cylinder marine engines fitted to launches, workboats, fishing boats and pleasure craft across the Gulf
Compact industrial
- Three- and four-cylinder industrial units under mini excavators, compact loaders, light towers, welders, compressors, pumps and small generator sets
Single-cylinder and small air-cooled
- In pumps, compactors and utility drives
- Read the section above before moving one of these
The failure map
What actually fails on a Yanmar in the Gulf
Salt water, on everything marine
Gulf water is hot and highly saline. Sea water pump impellers, heat exchanger and cooler tube stacks, and sacrificial anodes are consumables here in a way they are not elsewhere. When an impeller sheds blades the pieces lodge downstream and start the next overheating problem — so every piece gets recovered.
Mixing elbows and exhaust risers
Where hot gas meets salt water the passage silts up with a hard mixture of carbon and salt while the wall corrodes from the inside. A partially blocked elbow raises exhaust back pressure — the engine loses power, runs hot and smokes, and nothing on the panel explains why. A perforated one lets water back into a cylinder. Cheap to check, expensive to ignore.
Low-load running and standing
Harbour work, standing by, slow manoeuvring, light generating loads: bores glaze, injectors coke, exhausts run wet, turbochargers foul. And on sets that spend most of their lives switched off, coolant inhibitor, rubber, batteries and fuel all degrade on the calendar rather than on the hour meter.
Fuel, dust and hours
Bunkered fuel, drum refuelling, warm tanks with a large air space, condensation and microbial growth — it reaches the injection equipment first. On the industrial engines it is dust and deferred filters instead, and the failures are almost all preventable.
Ships' auxiliaries
The work nobody plans for
A vessel's auxiliary generating engines are the most under-attended machinery on board. They run continuously while the main engine rests, they are maintained around a schedule that is always subordinate to the ship's programme, and a failure on one of them puts the vessel in a considerably worse position than most people ashore appreciate.
The work is the same discipline every time: cylinder heads off for valve and seat reconditioning and pressure testing, fuel valves and pumps to the bench, liners and running gear measured, and the heavy components machined where the readings say they are recoverable. What varies is the time available.
The arrangement that makes a sailing date achievable is simple: the component travels and the vessel stays. Heads, fuel valves, pumps, turbochargers, coolers and running gear come ashore to Industrial Area 15 for machining and bench work, and go back. The alternative is a vessel alongside waiting on a replacement part with a manufacturing lead time attached to it.
Tell us where she is lying and when she sails, and the job is scoped against that date rather than against a workshop queue. See auxiliary engine repair, marine main engine repair and marine and shipping.
- Full overhaul
Strip, measure, machine, rebuild and run — see diesel engine overhaul.
- Cylinder heads
Valves and seats reconditioned, faces machined, castings pressure tested.
- Liners, pistons and running gear
Bores and liners measured, liners fitted and seated, pistons and rings assessed, connecting rods resized and checked for bend and twist.
- Crankshafts and blocks
Grinding, block machining and line boring in our own machine shop rather than sent to a subcontractor.
- Fuel equipment
Fuel valves, injectors, injection pumps and governors stripped, tested and calibrated on our own benches, with a test report per unit.
- Cooling and turbochargers
Heat exchangers, coolers and exhaust components cleaned, pressure tested and assessed; turbos stripped, rebuilt and balanced. Starter motors and charging alternators overhauled on the bench.
Where an engine is electronically managed, tell us at enquiry stage and we will confirm what can and cannot be addressed on the control side before you commit — a shorter conversation than a wasted attendance.
Before you commit
Have it measured
On any Yanmar large enough to be worth machining, the decision that matters is not “repair or replace the engine”. It is whether this crankshaft, these liners and these heads are still within limits — and that is a measurement, not an opinion.
A crankshaft's repairability turns on ovality, hardness, bend and crack depth, and on how much material remains above the manufacturer's bottom permitted undersize. A liner turns on wear, taper and ovality. A head turns on flatness, seat recession and cracks. Every one of those readings is taken here, in the same building where the machining would happen if the answer comes back favourably.
So the low-commitment first step is not a quotation and not a parts order: send the component and let us measure it. You get the readings with the manufacturer's limits beside them. If the part is past recovery you will be told so, and if the sensible answer for your engine is a replacement unit rather than a repair, you will be told that too. Nothing is machined or ordered until you say yes.
- WarrantyInside its manufacturer warranty, work outside the authorised network can affect cover. Use the dealer — we will say so on the phone.
- Parts policySome marine and offshore procurement policies require manufacturer-supplied parts only. If yours does, that points at the dealer.
- Lead timeA crankshaft ground here does not have a shipping schedule attached to it, and on a vessel with a charter to meet that difference is the whole job.
- MachiningAuthorised networks generally replace major components. Our machine shop exists to give the other answer: measure it, and bring it back to specification where the readings allow.
- Tooling and dataDealers hold factory tooling and current bulletins as a matter of course. An independent workshop has what it has invested in. Ask any workshop — including us.
Straight answers
Frequently asked questions
Are you a Yanmar dealer?
No. We hold no brand dealership of any kind, and we say so on our own site. We are an independent workshop that repairs and overhauls Yanmar engines.
Is my small Yanmar worth repairing?
Sometimes it is not, and you should ask that question before you move anything. On the smallest engines the cost of a full component overhaul can approach the cost of a replacement unit, and very small work we decline outright. Send the model, serial and symptom and you will get a straight answer, including the answer that says do not repair it.
My marine Yanmar overheats and has lost power. Where do I start?
Check the raw water side before anything else — impeller, strainer, cooler and, in particular, the mixing elbow and exhaust riser. A partly blocked elbow raises exhaust back pressure and produces exactly those symptoms while every gauge on the panel reads normally.
Can you overhaul a ship's auxiliary engine alongside?
Diagnosis, measurement and top-end work are done where the vessel is, and the heavy components come ashore to the machine shop and go back. Tell us where she is lying and what the sailing date is, and the job is planned backwards from that date.
Can you test and calibrate Yanmar fuel valves and injectors?
Yes, on our own bench, with a test report per unit showing opening pressure, spray condition and seat tightness. Label each unit with its cylinder number before it comes off — it makes the results far more useful. See marine fuel pump and injector repair.
Do you use genuine Yanmar parts?
We quote genuine parts where you want them or your policy requires them, and quality aftermarket where that is the sensible choice — and the quotation states which is which. Parts are sourced per job, and the realistic wait is given to you before you commit.
Which Yanmar models can you work on?
Send the model and serial number from the plate rather than a description. That identifies the build, which is what determines parts, clearances and settings, and it is what lets us tell you before anything is moved whether yours is a job we take.
Get a Yanmar engine quoted
The engine model and serial number, the installation, the running hours and the symptom. Photograph the plate. For a vessel, tell us where she is lying and what the sailing date is.