A structured yard survey for the Yanmar 3GM30 (≈ 27 hp · 3-cyl naturally aspirated). 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.)
NA triple: compression via the injector / glow port; confirm valve-clearance spec; inspect the mixing-elbow bore.
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.
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.
The GM classic pair — the elbow cokes/corrodes (often by ~1000 h) and, left alone, the restriction reaches the exhaust port and can need a head recondition; a corroded elbow also lets seawater back into the manifold/cylinder. The impeller’s centre bush can part from the rubber (fine at idle, fails at high revs). Inspect the elbow bore.
Older GMs weep oil at the rear main and can seep coolant (if FWC) — check the bilge and the oil.
Worn injectors, weak compression, tired starter/battery on a cold NA engine — check decompression levers and the start circuit.
Old rubber mounts sag; on a saildrive check the diaphragm age, boot and seals.
The ABYC & maker references behind the flags above — thoroughness the customer can see.
Sources: Yanmar 3GM30 operation / service manual; marine-service 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.