Sail Onyx

Diesel Engine Installations    |    Diagnostic & Repairs    |    Maintenance & Preventative Services

Marine Diesel Engines

Comprehensive and convenient care so you can navigate the miles with confidence.

Your marine diesel engine is made up of thousands of parts — all working together to deliver you seamless performance, reliability, and safety as you travel. When you need a skilled and professional marine mechanic to keep it all going, Onyx can help. Our full service mobile marine mechanics make service convenient by coming to your dock, marina, or boatyard.


We provide marine diesel repowers, repairs, and routine preventative maintenance services on most models such as Yanmar, Cummins, MTU, Caterpillar, Westerbeke and more.

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Marine Diesel Engine Installations

Repowering can be one of the most significant upgrades to your vessel—you’ll get an ultra-reliable engine with more power, better fuel efficiency, and fewer maintenance costs.


Our master marine mechanics give you the professional installation and elevated service you’re looking for.


We are committed to your project all the way through.  For example, after a new installation, we follow up within a few weeks for an additional onsite visit to make sure all your questions are answered.

Marine Diesel Diagnostics & Repairs

You depend on your engine to keep you and your vessel safe. Finding a marine mechanic you trust to properly troubleshoot and make high-quality repairs the first time is essential for confidence in your engine.


Our master mechanics are highly trained and experienced. In addition, our mobile team will come to you and handle a full spectrum of diesel engine services.


Alignments and Motor Mounts

Disruptive vibrations can be a sign of loose or damaged motor mounts or that you need an engine alignment.  Drips or splatters seen in your bilge are indicative of fuel, water, or oil leaks that may need attention.



There are many reasons your engine may overheat, like a clogged seawater intake.  Or, the problem could be internal such as a worn raw water pump impeller. A heat exchanger or exhaust manifold that needs serviced can also cause overheating.


Quickly diagnose the source of your problems and get professional repairs done right the first time with our experienced marine mechanics.


Not Starting & Poor Performance

Some repairs are more complex, both to diagnose and to repair.


Being able to rely on an experienced mechanic who can quickly pinpoint and perform higher complexity repairs is important.  It can determine how fast and how well the repair is done the first time.

Maintenance & Preventative Services

Be confident your marine diesel engine will take you wherever you want to go—and bring you home.

Preventative maintenance and regular inspections will prevent most breakdowns.


You’ll also extend the life of your engine, get maximum fuel efficiency, and lower overall maintenance costs.


Oil and Filter Changes

Changing the oil and replacing the fuel, oil, and air filters routinely allows your diesel engine to operate most efficiently and reduces wear.


Belts and Tension

Regularly checking the conditions of your belts can prevent unnecessary wear from improperly tensioned or misaligned belts.  When worn, we can replace them.


Valve Adjustments and More

Your engine needs more in-depth preventive care at specified intervals such as engine alignments, valve adjustments, heat exchanger flushing, and inspection of all wiring and alarms.


Our mobile marine mechanics come to you to perform a comprehensive checklist of services as needed.


In addition, you will receive a full report of what we did, recommendations, and photographs so you can feel competent that your marine diesel is running efficiently.

Marine diesel engines are rugged machines, but they are not indestructible. In the unforgiving marine environment, they often need repairs or maintenance to keep them performing efficiently and reliably.  Delaying service can lead to shortened engine life expectancy and higher repair bills later.

Contact Our Marine Specialist Today!

An Onyx specialist will contact you within an hour after submitting a request.

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