Suzuki outboard motors 1988 2003 repair manual., Page 248Get this manual
7-36 POWERHEAD performed on this assembly may make scrap out of an otherwise good castingThe cylinder assembly casting and other major castings on the outboard are expensive and need to be cared for accordinglyThere are three parts to the cylinder assembly, the cylinder block, the cylinder head and the crankcase halfThe cylinder block and crankcase half are married together and line bored to receive the crankshaft bearings, reed blocks and on some powerheads sealing ringsAfter this operation they are treated as one casting Remember that anything done to the mating surfaces during service work will change the inner bore diameter for the main bearings, reed blocks and sealing rings and possibly prevent the block and crankcase mating surfaces from sealingThe only service work allowed on the mating surface is lapping operation to remove nicks from the serviceCarefully guard this surface when other service work is being performedThe different sealing materials used to seal the mating surfaces are sealing strips, sealing compound and Loctite? Since the 2-stroke powerhead operates like pump with one inlet and one outlet for each cylinder, special sealing features must be designed into the cylinder assembly to seal each individual cylinder in multi-cylinder powerheadEach inlet manifold must be completely sealed both for vacuum and pressureOne way of doing this internally is with labyrinth seal, which is located between two adjacent cylinders next to the crankshaftIt may be of aluminum or brass, formed in the assembly and machined with small circular grooves running very close to machined area on the crankshaftThe tolerance is so close that fuel residue puddling in the seal effectively completes the seal between the cylinder block and crankcase halves against the crankshaftCrankcase pressures are therefore retained to each individual cylinderNo repair of the labyrinth seal is madeIf damage has occurred to the seal, the main bearings have allowed the crankshaft to run out and rubAnother method of internal sealing between the crankcases is with seal ringsThese rings are installed in grooves in the crankshaftWhen the crankshaft is installed, the sealing rings mate up to and seal against the web in the cylinder block crankcase halves and crankshaftSealing rings of different thickness are available for service workThe side tolerance is close, so puddled fuel residue will effectively complete the seal between crankcases and crankshaftTo seal the ends of the cylinder assembly around the crankshaft, O-rings are installed around the end caps and neoprene seals are installed inside the cap and seal against the crankshaft05007G2Z