Here's a standard leak down test procedure to isolate and identify which component is leaking.
The following is a test procedure to determine which component is causing the leak down. You will need a 3/16” brass cap and also a 3/16” plug. Both are available at Ace Hardware or some auto stores.
Step 1: Test the tilt cylinder for leak down
- Raise the tilt cylinder fully and then support the motor with a suitable block
- Relieve pressure by slightly tilting down
- Disconnect “raise” line from pump assembly connecting to the bottom of tilt cylinder
- Cap line with the female brass cap and also the valve body port
- Remove block support from gearcase
- Mark across the swivel and stern bracket with a marker to note movement. This may take a few minutes to about 30 minutes to see movement or leak down
- If leak down is noted, replace tilt cylinder or in your case rebuild it.
- IF NO LEAK DOWN IS NOTED RECONNECT LINE AND PROCEED TO NEXT PROCESS
Step 2: Valve Body leak down test
- Lower the outboard motor to full trimmed down position
- Remove the “lower” trim cylinder line from the valve body. This line is the one located on the upper portion of the trim cylinder. Plug and cap both the line and the valve body port.
- Raise the motor to fully up position (Full tilt)
- Mark across the swivel and stern bracket with a marker to note movement
- If leak down occurs, troubleshoot the valve body
- If leak down DOES NOT OCCUR, REBUILD OR REPLACE TRIM CYLINDER. NOTE THIS IS WITH THE CONCLUSION THAT THE TILT CYLINDER PASSED THE LEAK DOWN TEST IN STEP 1.
Let us know of you diagnosis. Make sure you familiarize yourself with all the parts and lines of the system before proceeding. If you have any question ask before instead of after.
