Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 157Get this manual
Powerhead Reassembly Main Bearing Selection
1Locate the upper and lower crankcase code letters on the crankcase cover2Refer to the following reference chart to select the correct main bearings3Use the color coded main bearings that match the crank case code letterCrankcase Code Letter Main Bearing Code Blue Black Brown
Main Bearing Installation
IMPORTANT: Do not interchange the main bearingsThey must be installed in their original position1Clean all the oil from the main bearing surfaces on the cylinder block and cylinder cover2Install main bearingsmake sure the locking lug on each bearing fits into the locking notch