Re: crankshaft seal
A bad top seal will often cause ignition problems on that outboard because the oil it spews will contaminate the points pretty quickly. It's a lot easier to diagnose - pop the flywheel off and if there's oil everywhere, check the seal.<br /><br />A bad bottom seal is trickier. I've seen really bad ones where fuel/oil will be spewed all up the exhaust housing and even in the bucket while running, but it's hard to be sure it's a marginally bad seal verses normal unburnt oil from the exhaust. Sometimes if you shine a flashlight up at the crankshaft with the lower unit off you can actually see whitish crud around the leaking seal. But usually there's some obstruction in the way.<br /><br />Bad crank seals will make for an impossible idle, as one cylinder will run much richer than the other. The problem will appear to go away as you rev up and the other cylinder kicks in, but it seems to me the engine will vibrate more perhaps due to the slightly different mixes at throttle. <br /><br />One thing though, if it's real bad there will be an obvious difference in the firing end of the spark plugs after "idling" for a couple minutes.
