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Overhaul · Revision · Rebuild

Yacht engine overhaul, planned to the hour.

Top-end and full overhauls of marine diesel main engines and generators — measured, phased and tested. A fixed scope, a fixed sequence and a documented result, carried out on board or with components reconditioned ashore.

Types
Top-end · In-frame · Full
Deliverable
Measured report and test data
Testing
Load test and sea trial
Planning
Phased around the yard period
When to overhaul

Overhaul at the right moment, not the expensive one

An engine tells you when it is approaching an overhaul long before it fails: rising oil consumption, falling compression, crankcase pressure creeping up, wear metals climbing in oil analysis, exhaust temperatures spreading apart between cylinders. Read early, an overhaul is a planned yard job. Ignored, it becomes a tow, a lifted engine and a cancelled season.

We assess condition first and then quote a defined scope. That means you decide between a top-end overhaul, an in-frame overhaul and a full overhaul with real numbers in front of you, rather than opening the engine and discovering the budget afterwards.

Options

Three levels of overhaul

LevelWork includedTypical trigger
Top-end overhaulCylinder heads removed and reconditioned, valves and guides, injectors, turbocharger service, valve train, gaskets and seals.Compression loss, smoke, valve or injector wear at mid-life hours.
In-frame overhaulTop-end scope plus liners, pistons, rings and main and big-end bearings replaced with the engine in the vessel.High oil consumption, blow-by, liner and ring wear at overhaul hours.
Full overhaulEngine removed, stripped and rebuilt: block and crankshaft measured, crank ground or replaced, all running gear renewed, engine test run.End-of-life hours, bearing or crank damage, or a rebuild to zero-hour condition.
Method

Measured, not guessed

  • Assessment — compression and crankcase pressure, oil analysis, boroscope inspection, operating data review, and a written condition report.
  • Scope and quotation — parts list, labour phases, yard requirements and lead times, with the decision points marked where findings could change the scope.
  • Strip and measure — every critical dimension recorded against manufacturer tolerance: liner bore and wear ridge, journal sizes, bearing clearances, head thickness, valve recession, injector spray pattern.
  • Reconditioning — machining and component work through established specialist workshops, with results documented.
  • Rebuild — assembled to torque and clearance specification, timing and injection set, protection systems verified.
  • Run-in and testing — controlled run-in, load test where a brake or shore load bank is available, then a sea trial with readings recorded.
  • Alignment — shaft and coupling alignment re-checked after any engine removal. See engine alignment.
You receive the measurement sheets. Not a summary — the actual numbers, so the vessel's file shows what tolerance every component was built to and the next engineer can compare against it.
Planning

Fitting an overhaul into a real programme

An overhaul is a logistics exercise as much as an engineering one: parts lead times, crane and yard access, engine room removal routes, class attendance and the vessel's charter or cruising calendar. We phase the work so long-lead parts are on order before strip-down begins and the engine is not sitting open waiting for a delivery. Where the vessel has two main engines, we can stagger them so the vessel stays operational.

Overhauls are carried out on Caterpillar / CAT, Cummins, MAN and MTU engines and on auxiliary generator sets. We are an independent engineering company, not an authorised dealer or official service partner of any manufacturer.

Questions we get asked

Frequently asked questions

How long does a yacht engine overhaul take?

A top-end overhaul on a medium-duty engine is typically one to two weeks on board. An in-frame overhaul commonly runs two to four weeks, and a full overhaul with engine removal and machining depends on parts and workshop lead times — usually several weeks. Parts availability, not labour, is normally the critical path.

Can an overhaul be done without lifting the engine out?

Often yes. Top-end and in-frame overhauls are done in situ when engine room access allows. Removal is only necessary when the crankshaft, block or bearing bores need workshop attention.

Is an overhaul worth it compared to a new engine?

For most superyacht and commercial installations an overhaul costs a fraction of repowering and avoids the engineering that comes with new mounts, controls, exhaust and classification. We give you both numbers so the comparison is honest, including cases where repowering genuinely is the better answer.

Will the engine be as reliable afterwards?

A properly measured overhaul with parts within manufacturer tolerance restores compression, oil control and thermal performance close to original. What determines the next 10,000 hours is run-in discipline, fuel and coolant quality and maintenance intervals.

Do you provide documentation for class or insurance?

Yes. Measurement sheets, parts records, test data and photographs are supplied in a form suitable for class surveyors, insurers and prospective buyers.

Service enquiry

Tell us about the engine and the vessel.

Send the details below and you will hear back from an engineer, not a call centre. For a vessel that is stranded or on a tight departure slot, call +31 6 20743967 or message us on WhatsApp.

Direct line

Considering an overhaul? Start with a condition assessment.

Send the engine type and running hours and we will advise whether a top-end, an in-frame or a full overhaul is the right investment — and what each option costs in time and money.

Superyacht Engine Service — powered by Marine Service Altena B.V.
+31 6 20743967 · info@superyachtengineservice.com
KvK 99330911 · Available for callout across Europe
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