300 Hour Boat Service
Protect your engine long-term with a professional 300 hour boat service.
Ethan, the owner and mechanic, answers the phone · Open 7 days a week
- Same / next day availability
- On-site & marina service
What Is a 300 Hour Boat Service?
A 300 hour boat service is a major maintenance interval that builds on your routine 100-hour services. Most manufacturers recommend completing it every 300 engine hours or every 3 years, whichever comes first. Not sure if yours is due? Check with the boat service due checker.
It’s designed to:
- Address deeper engine wear and internal components
- Replace parts with longer service intervals
- Prevent performance loss and unexpected failures
- Extend the overall life of your engine
Trusted by boat owners across South Florida
Read our Google reviewsNo call center. No front desk.
When You Call, the Owner Picks Up
Every call goes straight to Ethan, the owner of EG Marine Services and the mechanic who does the work. There’s no receptionist taking a message and no waiting on a callback from someone who’s never seen your boat.
Tell him what’s going on: the alarm on the display, the noise at idle, the engine that won’t turn over. Ethan knows Yamaha, Suzuki, Mercury, and the rest of what runs in South Florida inside and out, so you’ll usually get a straight answer on the first call, whether that’s something you can check yourself or a visit to your dock.
- Straight answers, not a script
- Diagnostic questions answered on the phone
- Honest advice, even when the fix is simple
- The person you talk to is the one who shows up
Ethan
Marine mechanic
Describe what the boat is doing and get a real answer from the mechanic, not a message taker.
Call Ethan: 786-351-5363Open 7 days a week
Due for your 300 hour service? Call Ethan and book it at your dock.
Call 786-351-5363Why the 300 Hour Service Matters
By the time your engine reaches 300 hours, normal wear starts affecting key systems more significantly. A professional 300 hour service keeps your engine running smoothly, efficiently, and reliably under load.
Without proper servicing:
- Internal engine components begin to lose efficiency
- Cooling system parts like the water pump wear down
- Fuel systems can develop buildup or restrictions
- Valve systems may fall out of optimal adjustment (on applicable engines)
Our 300 Hour Service Process
We keep everything clear, efficient, and thorough.
- 01
Initial Assessment
We review engine hours, usage patterns, and service history.
- 02
Full Service Execution
We perform both standard maintenance and deeper service items required at this interval.
- 03
System Checks & Inspection
We inspect critical systems and components that show wear over time.
- 04
Final Testing
We verify performance and ensure your engine is operating correctly before completion.
What’s Included in Our 300 Hour Service
This service includes everything from a 100-hour service, plus additional deeper maintenance.
Engine Oil & Filter Change
- Replace engine oil and filter
- Inspect for contamination or abnormal wear
Lower Unit Gear Lube Service
- Drain and inspect gear lube
- Check for water intrusion or metal particles
- Refill with manufacturer-recommended lubricant
Fuel System Service
- Replace fuel filters
- Inspect fuel lines and connections
- Address fuel system performance issues
Spark Plug Replacement
- Replace spark plugs (not just inspect)
- Ensure proper combustion and performance
Water Pump / Impeller Service
- Inspect and typically replace impeller
- Ensure proper cooling system performance
- Reduce risk of overheating
Valve Adjustment (If Applicable)
- Adjust valve clearances on compatible engines
- Maintain proper engine timing and efficiency
Propeller & Prop Shaft Service
- Inspect propeller and shaft
- Remove debris and check seals
- Reinstall with proper lubrication
Electrical System Check
- Inspect battery and charging system
- Check wiring, grounds, and connectors
- Apply corrosion protection
Anodes & Corrosion Protection
- Replace worn anodes
- Ensure proper protection against corrosion
Comprehensive Engine Inspection
- Check for leaks, wear, or developing issues
- Inspect hoses, clamps, and internal components
- Identify long-term maintenance needs
Why Choose EG Marine for Your 300 Hour Service
Not all 300 hour boat service providers go this in-depth.
Deeper, Not Just Routine
We focus on long-term engine health, not just basic maintenance.
On-Site Convenience Available
Service can be performed at your dock or marina when possible.
Experience with High-Hour Engines
We understand what starts to wear, and what to watch for, at this stage.
Clear Recommendations
We help you plan ahead so you’re not surprised by future repairs.
From the Job Log
Worn spark plugs removed during an outboard service 
Burnt outboard water pump impeller with missing vanes
Schedule Your 300 Hour Boat Service Today
Stay ahead of major maintenance and protect your engine investment.
Call Ethan directly786-351-5363Open 7 days a week · No call center or front desk, you talk to the person doing the work
- Flexible scheduling
- Experienced marine technicians
- Service at your location or marina
Prefer a free quote?
Leave your number and we’ll call you back.
300 Hour Boat Service FAQs
What’s included in a Yamaha or Mercury 300 hour service?
Everything in a 100 hour service plus spark plugs, the water pump impeller, thermostats, and a valve adjustment where the engine calls for it, following Yamaha, Mercury, Verado, or Suzuki specs.
How much does a 300 hour service cost?
It depends on the engine and how many you have. Call Ethan with your engine model and hours for a price before he comes out.
What makes a 300 hour service different from a 100 hour service?
A 300 hour service is more in-depth. While a 100-hour service focuses on fluids and basic inspections, the 300-hour interval includes component replacements and deeper mechanical checks, such as the water pump and, in some engines, valve adjustments.
Is the water pump always replaced at 300 hours?
In many cases, yes. Even if it’s still functioning, the impeller is considered a wear item and is often replaced preventatively at this stage to avoid overheating issues later.
Do all engines require valve adjustments at 300 hours?
Not all engines do. Valve adjustments depend on the engine type and manufacturer specifications. If your engine requires it, we’ll include it as part of the service.
Can I delay my 300 hour service if the engine feels fine?
It’s not recommended. Many of the components addressed at this interval wear gradually and don’t show obvious symptoms until failure is close. Staying on schedule helps prevent sudden issues.
Will this service help extend engine life?
Yes. A properly completed 300 hour boat service plays a key role in extending engine life, maintaining performance, and reducing the likelihood of major repairs.
Areas We Serve
Our mobile marine mechanics travel to marinas, private docks, and waterfront homes from Boca Raton to Islamorada. Nearby but not listed? Reach out to confirm availability in your area.