How to Pressure Test Yamaha 60HP Outboard Gearcase

Whether you’re changing out fluids or replacing seals on your outboard’s lower unit, you should go ahead and do a pressure test while the gearcase is removed.

Pressure testing the lower unit helps you detect problems such as leaking seals, which can lead to major problems with your engine. A gearcase pressure tester is all you need to get this simple task done. Watch the video above and follow the steps below to learn how to do a lower unit (gearcase) pressure test on a Yamaha outboard. Use our Yamaha 60 lower casing drive parts diagram for additional reference.

Tools Needed – Yamaha 60 Gearcase Pressure Test

  • Pressure tester
  • Flathead screwdriver

NOTE: We pressure-tested a Yamaha 60HP outboard, but the process is virtually the same for most outboard makes and models. 

Yamaha 60HP gearcase pressure test

Before pressure testing the gearcase of your Yamaha 60 outboard, you need to remove it. Watch the video below to see how to remove the lower unit on a Yamaha 60 outboard motor.

Pressure Testing a Yamaha 60HP Outboard Lower Unit

Step 1. Drain out the oil from the lower unit, then reinstall the oil drain/fill bolt.

Yamaha 60HP lower unit pressure test

Step 2. Attach a gearcase pressure tester to the lower unit via the upper oil level bolt hole, making sure to use the correct adapter to fit the hole.

Yamaha outboard gearcase pressure test

Step 3. Pump the pressure tester to increase the pressure within the gearcase to about 12psi.

Yamaha outboard lower unit pressure test

NOTE: Keep an eye out for bubbles coming from the input and output shaft seals as you’re pressurizing the gearcase, which is a sign of leaks.

Step 4. Leave the pressure tester attached to the gearcase for a couple of minutes, then check the pressure level. 

If the PSI level stays the same, the seals are holding and the lower unit can be reinstalled to the motor. However, if the PSI level drops, a seal or seals are leaking and you’ll need to find the leak(s) and replace the seal(s). 

Ready to mount the lower unit back onto your Yamaha outboard motor? Watch the video above to see how to remount the gearcase on a Yamaha 60HP outboard. 



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