What sterndrive repair covers
- Bellows replacement: the drive bellows, exhaust bellows and, on Alpha drives, the shift-cable bellows
- Gimbal bearing inspection and replacement when the drive is out for bellows service
- U-joint and drive alignment, checked with an alignment bar so the drive slides on by hand
- Gear lube service with a check for milky lube, a sign of a seal leak
- Drive anode inspection, bullet, trim tab and prop anodes
- Shift and trim troubleshooting
The $150 visit fee is credited to the job. You get the price in writing before any work starts.
Cracked bellows is the most common sterndrive failure
A sterndrive's bellows seal the gap between the transom and the drive. They are rubber and they perish with age, and once they crack, water gets into the gimbal bearing and U-joints, which is a far more expensive repair than the bellows themselves. It is common shop practice to plan on bellows service every several years rather than waiting for a visible crack, and to inspect the gimbal bearing any time the drive is off.
MerCruiser bellows are bonded with Quicksilver bellows adhesive, a contact cement, not 3M 5200. 3M 5200 and 4200 are polyurethane sealants and are the wrong chemistry for a bellows joint. This is one of the more common mistakes on a DIY bellows job.
Alpha, Bravo and Volvo Penta each have their own parts
MerCruiser Alpha One is the common drive on lighter gas boats, Bravo One and Two are higher-performance and heavier-displacement single-prop drives, and Bravo Three runs twin counter-rotating props with its own anode set. Volvo Penta's SX and DP drives are the main alternative, with their own bellows, adhesive and service procedure. Gear lube capacity, gimbal and U-joint torque, and the drive alignment specification are all specific to the exact drive model, so Brad works from the unit's own service manual for those numbers rather than a generic figure.
Milky gear lube usually means a seal is leaking
If the gear lube monitor bottle shows a milky or cloudy fluid instead of clear oil, water has gotten past a drive seal. It is worth checking at every haul-out and every gear lube service, because it is one of the earliest warnings of a bigger drive problem. See the haul-out inspection checklist for what else to look at when the boat comes out.
Want to understand the job first
The sterndrive winterizing guide walks through what a DIY-minded owner can check and do themselves, and where the job calls for a professional set of alignment tools and a supported drive. If your engine won't start at all rather than the drive itself acting up, see boat won't start.
Where Brad does sterndrive work
Common questions
How do I know if my bellows need replacing?
Cracking, dry rot, or a shop finding water in the gimbal housing at haul-out are the usual signs. Bellows are rubber and perish with age even if the boat sits most of the season, so shops generally service them every few years rather than waiting for a visible tear.
Is bellows adhesive the same thing as 3M 5200?
No. MerCruiser bellows are bonded with Quicksilver bellows adhesive, a neoprene contact cement, not a polyurethane sealant like 3M 5200 or 4200. Using the wrong adhesive is a common DIY mistake.
How do you know if the gimbal bearing is bad?
A rough or growling feel when it's spun by hand, usually from water intrusion through failed bellows, is the classic sign. Brad checks it any time the drive is off for bellows service.
Do you work on Volvo Penta drives too?
Yes, though Volvo Penta SX and DP drives use their own bellows parts and adhesive, different from MerCruiser. Brad follows the Volvo procedure and parts for those, not the MerCruiser one.
Problem with the engine itself rather than the drive? See marine engine repair.
Growl in gear, water in the gimbal, or a haul-out surprise
Text a photo of what you're seeing and Brad will tell you what he thinks it is.