A little oil on the water. A lot of money in the gearcase.
The lower unit is the most expensive part of an outboard that people ignore. A seal that lets water in turns the gear oil milky, and milky oil grinds gears and bearings. Caught early it is a seal job. Caught late it is a new gearcase.
Fishing line behind the prop. Monofilament wraps around the prop shaft, works its way behind the prop, and cuts the prop shaft seal. It is the single most common cause we find, and the cheapest to prevent: pull the prop once a season and look.
Aged or damaged seals. Prop shaft, drive shaft and shift shaft seals harden with age and heat. Oil weeps out at the prop or at the top of the gearcase, and water gets in the same way.
Drain and vent screws and their gaskets. A missing or crushed gasket, or a screw left loose after the last oil change, leaks oil out and lets water in. Simple, and often overlooked.
Checking the oil means pulling the lower drain screw. If you are not comfortable doing that with the boat out of the water and a catch pan ready, leave it for the visit; we will show you what came out.
If the oil is milky, stop running the boat. Water in the gearcase rusts bearings and pits gears within days, and a hard run with water inside can lock the lower unit. A pressure and vacuum test tells us which seal failed. Do that now, and it stays a seal job.
We drain the oil and read it, pressure- and vacuum-test the gearcase to find the failing seal, replace the seals and gaskets, and refill with the correct gear oil. If the oil shows metal, we tell you straight what the gearcase needs before any work starts.
Regular hours (6am–4pm): a $200 diagnostic visit. We come to the boat, find the actual cause, and quote parts and labor before any work starts. After hours, Sundays and holidays: a $295 call-out. Parts, labor and sales tax always show as separate lines on the invoice, so you can see exactly what you paid for.
Can I just change the oil and keep going?
If the oil is only slightly cloudy and the leak source is fixed, sometimes. If it is milky, water has already been in there, and the bearings need to be checked, not just the oil.
How do you know which seal failed?
We put the gearcase under pressure and then under vacuum and watch where it loses it. That points at the exact seal instead of guessing.
Is a lower unit rebuild worth it on an older engine?
It depends on the engine's condition and hours. We give you the seal-job price and the rebuild or replacement price side by side, and you decide.
Dock, lift, marina, driveway or storage lot — we come to the boat across Southwest Florida:
Text us the engine and where it sits. A seal job at the dock costs a fraction of a gearcase, and it is the same visit for us.
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