A structured yard survey for the Yanmar 6LP (≈ 300–370 hp · 6-cylinder turbo-diesel). Factory service due by hours, the full inspection with pick-the-fault detail, oil sampling, common-failure watch-outs and red-line stop items, optional compression. The overall result is computed from the findings, then emailed to the North or South desk.
Enter the hours — the factory-service section flags what should have been done.
Type the builder / model above — logged model-specific failures appear here to check (e.g. Ranger/Cutwater water ingress → transmission sensor & ECU).
Enter the builder / model above — known issues for that boat appear here.
Right tools on the first trip = a complete survey and no return visit. (Kaizen: stage the cart.)
6LP note: compression via the injector port (diesel adapter); confirm the valve-clearance spec; pressure-test and borescope the aftercooler tube bundle.
Milestones at or below the hours are flagged DUE. Mark whether each is Present in the records — a missing one counts as a maintenance item.
Flag an item and pick the exact fault (or write it in).
Belts, tensioner, running test, smoke, leaks — pick the fault on any flag.
Motor mounts & vibration, in/out of gear, shift resistance, coupling out to the shaft seal.
Mounts & vibration
Gearbox / transmission
Coupling out to shaft seal
Oil sample numbers (port/stbd), coolant colour vs the maker’s spec, and test-strip results.
Oil sampling
Coolant
Universal marine-diesel checks plus this engine’s known weak points — each with the standard it touches.
These common-issue checks catch the problems that become callbacks — and they are the honest upsell: the customer sees exactly what needs doing and leaves with a better, more reliable engine.
Walk the whole engine: weeping covers/seals, oil cooler, fuel at the filters/injectors, coolant at hoses/pump, and exhaust soot at the elbow. Small leaks are a cheap fix now and a callback later.
Pull the intake / intercooler hose and look for pooled oil — turbo shaft-seal wear or heavy blow-by pushing oil into the charge air. It fouls the aftercooler and robs power; the classic ‘looked fine until it wasn’t.’
Glazing, cracks, fraying, black dust and correct tension; check the tensioner / idler bearing. A $30 belt caught here beats a no-charge or an overheat on the water.
Squeeze every hose — hard, cracked, soft or swollen; wet-exhaust & raw-water hose hardens with heat and age. All-316 clamps, doubled below the waterline. The cheapest failure to prevent.
Impeller vanes (full set, cracks, missing pieces gone downstream), pump cover/cam wear, strainer and flow at the exhaust — the number-one overheating cause.
Green-white corrosion on terminals, chafed harness, loose grounds and battery connections — intermittent faults and hard starts start here.
Cracked or collapsed mounts, oil-soaked rubber, movement under load — the root of vibration and seal / coupling wear.
Coolant strength and condition and the heat-exchanger pencil anodes — neglected coolant and spent anodes quietly eat the cooling system.
1997–2002 6LPA 300/315 hp: faulty valve-stem seals wipe oil, the valve sticks, and the piston strikes it — the #1 exhaust valve can let go near ~700 h. Gray seal rubber = the bad seals. Watch for a single-cylinder misfire / low compression. Check the Yanmar extended-warranty SN range (50101–53988 / M50001–M51195; 5000 h or 8 yr).
Serial numbers 50101–53988 can suffer injection-pump wear → rough idle and power loss.
Service on schedule — a neglected, salt-fouled tube bundle can fail catastrophically and push water into the charge air / oil. Pressure-test / clean per hours.
Raw-water turbo diesel: the exhaust mixing elbow/riser corrodes and scales internally — restriction and water intrusion. Inspect the bore, not just the outside.
Heat-exchanger fouling, raw-water pump impeller wear, and neglected coolant are the usual overheating causes — check the whole raw-water path and coolant condition/anodes.
The ABYC & maker references behind the flags above — thoroughness the customer can see.
Sources: Yanmar 6LP-DTE / 6LP-STE service manuals (periodic maintenance — valve clearance & injection check at 250 h and 1000 h); Yanmar extended-warranty bulletin for the 6LP/6LPA exhaust-valve-seal and injection-pump issues (SN 50101–53988 / M50001–M51195); marine-survey best practice.
Check any that are present. Any one flags the survey for immediate service.
Optional — recorded and marked present only if performed.
Port / single (psi)
Starboard (psi, twin)
The result is derived from the survey, not a judgment call.
Computed from the findings above — red-line = immediate; otherwise significant vs maintenance issues set the result. Not a manual rating.
Pick the Yard below, preview, then send — the full report emails to that desk.