Lower units and water pumps
The lower unit holds the gears, the seals, and the water pump that keeps the whole engine alive. Milky gear lube coming out? Water's getting past a seal, and that's a job for now, not for the autumn. The impeller in that water pump is rubber. It takes a set while the boat sits, and it's the single most common reason an outboard overheats.
Prop shaft damage, a spun hub and a bent blade all show up as vibration, and a vibration that is ignored works its way up into bearings and seals.
Fuel systems and powerheads
Carburetors and fuel injection both suffer when fuel sits. Filters, water separators, primer bulbs, lines gone hard, injectors or jets that have varnished: it's all one story. Powerhead work sits way down at the far end of that road, and you can usually avoid getting there.
Honda and Suzuki outboards
Honda and Suzuki four-strokes are all over this lake alongside Mercury and Yamaha, and both get worked on here. Every brand has its own service schedule, its own diagnostic software and its own quirks (valve clearance intervals, timing belt or chain, how the fuel system's laid out), so the work follows the manufacturer info for the engine in front of it. Not a one-size routine.
On any four-stroke outboard that sits for half the year, the same jobs keep coming around. An impeller that's taken a set. Stale fuel. A sticking thermostat. Oil and gear lube that are due whatever the hours say. And if the question's moved on to a repower, Honda and Suzuki are two of the brands to talk through.
Annual service
An annual outboard service is oil and filter where the engine has them, gear lube, spark plugs, a new impeller on schedule, anodes, a fuel filter and a proper look at the steering and trim. It is the best-value hour on the boat.
What a short season does to an outboard
An outboard on Lake Winnipesaukee works for roughly half the year and sits for the other half, and the sitting causes more failures than the running. Rubber components take a set: the water pump impeller deforms against its housing over six still months, and pumps less on the first hot day than it did in October.
Fuel is the second half of it. Pump gasoline in most of the country contains up to ten percent ethanol, which draws moisture out of the air and separates over a long layup. What comes out of a tank in May is not what went into it in October, and carburetor jets and injectors are the first things to find that out.
Batteries, meanwhile, self-discharge all winter and sulfate if they are left discharged. Between the impeller, the fuel and the battery, three of the most common spring failures on this lake are storage problems wearing the costume of engine problems.