1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 164Get this manual
POWERHEAD
6Remove 10 bolts and separate exhaust cover and exhaust manifold from cylinder block
NOTE: If engine is suspected of having been overheated or spark plugs are grayish colored (a sign of possible water intrusion), inspect exhaust manifold for warpage or for proper placement and integrity of gaskets which mayl allow water to enter cylinders through exhaust ports7Remove bolts and intake cover
NOTE: 1995-newer Model 9.915 powerheads have O-rings under intake cover instead of gasketThis style intake cover with O-rings WILL NOT backfit prior models