I had to remove the block due to a broken bolt for the starter. Now after fixing that issue I cant get the block to seal at the base of the lower unit. I am getting exhaust blow back into the motor pan and shroud. I have tried 4 different gaskets of various thicknesses and permatex with no luck. I was told that removing the motor after 20 plus years could cause some issues. Is this my problem? The motor never ran hot. Actually it runs perfect except for the exhaust blow back. It's not sealing at the base under the carb on the starboard side. Any one ever fixed this issue?