Yamaha Outboard F15A F9.9C, FT9.9D F15 Service Manual, Page 134Get this manual
INSP ADJ
POWER UNIT
6Install: Oil filler cap 7Check: Engine oil level Refer to "Engine oil level"
NOTE: Run the engine for several minutes, turn it off, and check the engine oil level9 If the engine oil is still not at the proper level, adddrain as neededTiming belt 1Inspect: Timing belt Weardamage Replace
2Check: Timing belt slack (Push the timing belt with your finger Out of specification ReplaceTiming belt slack a:10 mm (00.4 in)