Excessive vibration due to misalignment of engine.

If an engine is out of alignment expensive repair bills are just around the corner! When an engine is out of alignment with the shaft, it leads to excessive vibration, wear of bearings in the gearbox, leaking transmission seals and wear in the cutless bearing.

Correct engine alignment with the shaft is critical and while flexible mounts and flexible couplings will help to minimize these problems if the job is not done properly in the first place no amount of flexibility will prevent wear on your transmission. Their job is to dampen vibration and deal with distortion due to hull flexing, but not to compensate for misalignment.

Once per season, ideally about a week after launching and stepping the mast, check the alignment of the engine in relation to the shaft. If necessary, it should be adjusted. Engine alignment is not difficult, but it can be a tedious procedure talking a long time and patience. A rough engine alignment can be done with the boat on land, but a final alignment check must be done and adjusted when the boat is in the water. To check alignment, remove the screws holding the 2 parts of the flange together. Use a feeler gauge with a thickness of 0.001? per inch coupling diameter. Check on 4 sides. If the spaces between the flange faces are different, hold the engine side of the coupling and rotate the shaft side 180 degrees. If the gap moves with the shaft rotation the shaft is bent or the coupling is not square to the shaft. If the does not move with the rotation of the shaft, the engine requires alignment.

Make sure that a brass key is fitted into the keyway slot in shaft & coupling. If a steel key is found, remove it and replace with a brass key. Sometimes a steel key will be used when a brass key shears, which is exactly the purpose of a brass key. The shearing of a brass key is an indication you have a problem to which you should attended.

Category: Engine Room