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In 25-plus years working on marine engines and gensets out of Seattle, we've learned the same lesson again and again: a generator almost never fails without warning. It gives you signs of failure first.
Why Marine Generators Fail Differently Than Land Generators
Raw water cooling is the biggest difference. Salt scales the heat exchanger from the inside, and the impeller's rubber vanes harden and crack with age and heat, usually with no visible symptoms until the engine starts running hot. Add the vibration of being mounted in a moving hull, and you get fastener and mount wear that a stationary unit never sees.
7 Signs Your Marine Generator Needs Service
Hard Starting or Won't Start
A slow, labored crank is electrical: the battery, then the cable ends and connections, then the starter and solenoid. When it cranks at normal speed and never catches, the problem is fuel: air in the fuel system, water in the fuel tank or lines, a plugged primary filter, or the glow plugs if it only happens cold.
Low or Fluctuating Output, or Tripping Breakers
If voltage stays low while the engine holds its speed, the voltage regulator is at fault. If you can hear the engine bog down as load comes on, the problem is fuel delivery or the governor.
Overheating, Weak Cooling Water, or Soot at the Exhaust
Check the seacock, the strainer, and the raw-water hose between them first, because kelp in the strainer can destroy a healthy impeller within an hour. A thinning stream at the outlet is the first sign an impeller is losing vanes, well before the temperature alarm.
Soot at the outlet, or a carbon monoxide alarm, means the mixing elbow is leaking exhaust before the water reaches it. Shut it down and call someone, it's pretty serious.
Excessive Smoke
Black smoke is too much fuel for the available air. White smoke on a cold start that clears within a minute is normal, but white smoke that persists means fuel is going in without burning. Blue smoke is oil getting past worn rings, valve guides, or turbo seals.
Unusual Noise or Vibration
Boats vibrate, so what matters is changes to the vibration. A knock that rises and falls with load is the serious one, and catching it early means you pay for a repair instead of a rebuild.
Rising Fuel Use or Rough Running
Fuel burn is the easiest sign to measure. Track gallons against the hour meter, and a number climbing over a season means the engine is working harder to do the same work.
It's Been Too Long Since the Last Service
Service runs on hours, not the calendar, so a generator with no smoke and no alarms can still be overdue. Most units want oil and filters between 150 and 250 hours, so check your manual. If it's been a while, our marine generator maintenance guide covers what a proper interval actually looks like.
What Happens If You Wait
Small issues on a marine generator compound. Generators tend to fail under load, which means they usually quit when you need them most.
When to Service vs. When to Call Right Away
Routine. Book ahead when annual service comes due, when you hit an hour-based interval, or when you notice a minor dip in performance that hasn't gotten worse.
Call now. A generator that won't start, an overheat alarm, heavy smoke of any color, or an electrical fault all need attention the same day.
How Hatton Power Services Marine Generators in Seattle
A real marine generator repair in Seattle covers more than an oil change. We inspect the cooling system for impeller wear and scaling, check the fuel system for contamination and flow, go through the electrical side including the voltage regulator and connections, and load test the unit to confirm it performs the way it's supposed to under an actual demand, not just at idle.
We do this work as an authorized KOHLER and ONAN dealer, with the parts inventory and the marine-specific background to back it up. Raw water systems, salt intrusion, and boat mounts are the default case here, not the occasional job, whether that means marine generator service in Seattle at our shop or a mobile technician coming to your boat.
Schedule Your Marine Generator Service
FAQ
How often should a marine generator be serviced?
Most manufacturers call for service at least once a year or after a set number of operating hours, whichever comes first, and a saltwater environment tends to push that toward the more frequent end.
How long does a marine generator last?
There's no fixed number. A generator that gets regular service, proactive impeller replacement, and clean fuel can run for a long time. Maintenance history matters more than age.
Do you service commercial marine generators in Seattle?
Yes. We work on commercial vessels and recreational boats, and we can talk through what a maintenance program looks like for a fleet or a working boat where downtime has a direct cost.
