Re: bf50 oil sample
You may not have an ongoing problem.
When I have encountered water in the oil, sometimes caused by making oil (see the Engine FAQ's sub-forum in Repair and Maintenance), I have found that a single oil change is not always enough to clear the milkshake from the crankcase, because the emulsion hangs all over the inside of the motor, especially if the oil is drained when the powerhead is cold. So a single oil change was also contaminated with milkshake.
In those cases, I have flushed the crankcase with ordinary shop solvent (Stoddard solvent, mineral spirits, high-flash naphtha, etc.) without running the motor, followed by fresh oil (and filter) and a brief tank test, (showing slight contamination) and THEN draining and refilling with oil (and fresh filter). Yes, it will require two filters.
In at least two cases, I found that the milkshake was caused by the crankcase being slightly over filled, and the motor not run hard enough to evaporate condensation in the crankcase. Two no-no's. In other words, there was nothing wrong with the motor; Just operator error.
In one of those cases, the foam-up was so bad that the motor stalled at idle, and when the owner tried to restart, the foam in the crankcase resisted the piston travel so much that the electric starter actually sheared off the woodruff key for the flywheel! This after an hour or so of running. Since the operator continued to crank and crank, he also wrecked the bore in the flywheel, as it spun around on the key fragments. After replacing the flywheel, a thorough crankcase flush, and a fresh oil change, the problem has not recurred.
If your compression is good, I would consider doing a second oil change to verify whether water is still getting into the oil. If it's not, then you saved tearing the motor apart. If there is still a problem, all you have lost is an oil change.
