Boat Lower Unit & Gearcase Repair in Miami

Annual Lower Unit Service

Every outboard and sterndrive should have gear oil changed at least once a year, more often for heavy use. The annual service includes:

• Drain and visually inspect old gear oil
• Check for water intrusion (milky color)
• Check for metal shavings (bearing or gear wear)
• Refill with manufacturer-spec gear lube
• Pressure test drain plug seals
• Water pump impeller inspection
• Anode (zinc) replacement
• Prop shaft seal inspection

Water Pump Impeller Replacement

The water pump impeller lives inside the lower unit and circulates cooling water to the engine. Impellers dry out, crack, and lose vanes with age. A failed impeller lets the engine overheat within minutes. We recommend impeller replacement every 2 years minimum, annually for heavy-use boats. During replacement we also inspect the water pump housing, pump liner, and cooling passages.

Lower Unit Seal Replacement

When gear oil comes out milky, seals are leaking. Common seal jobs include:

• Prop shaft seal (most common failure, usually from fishing line wrapped around the shaft)
• Drive shaft seal (harder access, requires gearcase removal)
• Shift shaft seal
• Pinion shaft seal

We replace seals properly, which often means full gearcase disassembly to reach the drive shaft seal. Not the fun kind of work, but done right once it lasts years.

Gearcase Rebuild

When water intrusion has gone unaddressed long enough, bearings and gears start pitting. That is where a gearcase rebuild happens. Full rebuild includes:

• Complete disassembly
• Clean and inspect every gear, bearing, and shaft
• Replace failed bearings (forward, reverse, pinion, drive shaft)
• Replace all seals
• Replace shift dog if worn
• Lap or replace gears if pitted
• Reassemble with proper shim stack (backlash measurement)
• Pressure test before reinstall

When Lower Unit Work Needs Haul-Out

Most lower unit service on outboards can be done at the dock with the motor tilted up. Sterndrive gearcase work usually requires haul-out since the drive has to come off the boat. We coordinate haul at partner yards as needed.

Lower Unit Problems We Fix

• Milky gear oil (water intrusion)
• Metal shavings in gear oil (bearing wear)
• Whining or grinding from the lower unit
• Hard shifting or no shift
• Popping out of gear under load
• Vibration that increases with RPM
• Overheating (water pump failure)
• Corroded drain plugs that wont come out

Lower unit problems only get worse. Catch them at the annual service and they are usually minor. Ignore them and they become a rebuild. Call (305) 290-2701 or request service.