Mercury Mariner 30/40 4-Stroke Outboard Service Manual 1998, Page 82Get this manual
IGNITION
Timing Belt Removal and Installation
Removal
1Remove timing belt from driven sprocket
aTiming Belt
Installation
1Align marks on driver and driven gear with marks on cylinder block as shown2Install timing belt onto drive sprocketSlide timing belt onto driven sprocketNOTE: Install timing belt with parts name up