If you have a Yamaha 4-stroke outboard, you have probably heard that “belt squeal” sound coming from your motor. The “F” series motors and the new “VF” SHO series motors are notorious for the sound after running the engine for prolonged periods of time, or after a high-RPM run. Fear not, the fix is actually really simple. On my 200 SHO, and possibly your motor, the fix is removing the lower unit, greasing the driveshaft splines and the oil pump seal surface. Yamaha designed a grease just for this, so let’s get to this maintenance fix.
Here’s what you’ll need to remove your Yamaha SHO’s lower unit and fix that annoying squeal:
14mm open end wrench for six of the lower unit bolts
8mm hex bit for the anode/trim tab cover
14mm socket wrench for the lower unit bolt underneath the anode/trim tab cover
Yamaha WR-2 Grease
Remove all (6) lower unit bolts with an open end wrench. There are (3) bolts easily accessible on each side of the lower unit.
Use your 8mm hex bit and remove the anode/trim tab bolt that you can see, as well well as the bolt underneath with your 14mm socket.
Slowly lower the lower unit making sure not to bend or damage the driveshaft.
Lay the lower unit down and clean off the driveshaft splines at the top, as well as the 1-inch surface that you see below the splines
Apply Yamaha’s WR-2 grease to the splines and the 1-inch surface Oil Pump seal surface.
Insert the driveshaft and slowly work the lower unit back on.
Once the lower unit slides up, align the shift rod and dowels.
Put all of your lower unit bolts back on, as well as the anode/trim tab bolt.
By doing this once a year, you’ll eliminate the squeal that often comes from Yamaha motors. While I’m no mechanic, this is a very easy “Do-It-Yourself” project. This information is intended to be helpful for those with a service manual who have the necessary tools for the job. By following this guide, it is not intended to replace a certified mechanic’s ability to service your outboard engine. All readers assume their own risk and liability from working on their outboard motors.