12. I am getting some oil leaking into my bilge, but I can't seem to locate the leak on my engine. Where are some likely spots to look?

Most oil leaks occur along the carburetor side of the engine. Starting at the flywheel end of the engine and working rearward, leaks could be from the oil sending unit directly behind the flywheel housing (or from its connecting fittings), or out from under the valve cover, or from between the block and fuel pump, or from around the oil pressure regulating valve.

If the leak seems to be from the rear of the engine, the rear seal around the output coupling could be leaking. However, most all leaks from along the carburetor side of the engine usually run back along the upper ledge of the oil pan and end up dripping off the aft end of the engine. Therefore, to be certain that the rear oil seal is really leaking, it is necessary to thoroughly clean the rear end of the oil pan so that the oil can actually be seen to run down from the seal.

On the starter side of the engine, leaks are usually limited to the area of the water pump, with the shaft seal of the pump (the seal toward the engine)usually causing the leak. Less likely, but if the leak is clearly coming from the front of the engine, it could be that the return holes in the flywheel housing below the air seal (or “slinger seal”) around the front of the crankshaft are clogged. When these holes are clogged, oil being flung outward by the tapered collar around the front of the crankshaft cannot drain back into the crankcase, and it is running (instead) down behind the flywheel, along the front face of the flywheel housing, and out through a drain hole in the bottom of the same housing. - Updated: November 4, 2003