1998 Mercury 9.9/15HP 4-stroke outboards factory service manual, Page 68Get this manual
IGNITION
Timing Belt Removal and Installation
CAUTION
The valves may occur damage if the driven gear or drive gear are rotated when the timing belt is removed or incorrectly installedIMPORTANT: To prevent valve damage If the timing marks are out of alignment, bring the timing marks into alignment as follows: 1Rotate the drive gear timing mark 90 away from its alignment mark without going past the alignment mark2Rotate the driven gear timing mark into alignment3Rotate the drive gear timing mark into alignment, 4Install timing belt with hands