Yamaha F225 Outboard Leak Down Test

If your outboard is performing poorly, the first thing you should do to diagnose the problem is a leak down test. 

The leak down test provides an excellent indication of the condition of each of the cylinders, as well as the overall condition of the motor. Watch the Yamaha F225TXRC outboard leak down test video above, and follow the guide below to get this job done. 

Tools Needed - Yamaha F225 Leak Down Test 

Yamaha F225 outboard leak down test

How to Do an Outboard Leak Down Test

Step 1. Remove the top cowling, and take off the ignition coil cover at the rear of the motor.

Step 2. Remove the spark plugs, and take off the flywheel cover from the top of the motor.

Step 3. Mark the flywheel with a marker at 0 degrees, 120 degrees and 240 degrees.

Yamaha outboard motor leak down test

Step 4. Set cylinder #1 to top dead center (TDC) by rotating the crankshaft with a ratchet and socket.

Yamaha outboard engine leak down test

Step 5. Adjust the regulator on the leak down tester to 0%. 

Outboard engine leak down test

Step 6. Connect the leak down tester to cylinder #1, and take a measurement while holding the crankshaft to prevent it from rotating.

Step 7. Rotate the crankshaft 360 degrees to put cylinder #4 at TDC.

Step 8. Connect the leak down tester to cylinder #4, and take a measurement while holding the crankshaft to prevent it from rotating.

outboard engine leak down testing

Step 9. Set cylinder #3 to TDC, and repeat Step 5 through Step 8 for cylinders #3 and #6

Step 10. Set cylinder #2 to TDC, and repeat Step 5 through Step 8 for cylinders #2 and #5

Hopefully the leak down test will show that your Yamaha F255 outboard is in good condition. However, if your motor is losing compression, it's time to break out your toolbox and start repairing your motor. 

Whether you think your motor is losing compression or not, we recommend running a compression test on your outboard anyway. Watch the video above to learn how to do a compression test on an outboard engine.

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