Last fall the fuel pump on my Chrysler 360 Marine went up. On a marine engine the fuel pump bypass dumps gas into the carb. I had it towed into the marina. I did not know the fuel pump went (and did not shut off the fuel line). I came back next weekend and the entire motor was flooded with gas (intake, combution chambers, and crank case).
So basically my entire motor was flushed with gas.
I turned off the fuel, pulled the spark plugs and hand-turned the motor to clear the intake and cylinders. I then pumped out the crank gas/oil mixture. I replaced the fuel pump, added oil and a new oil filter.
I ran the motor maybe 3 minutes. The oil looked like dirty and thin honey.
I changed the oil and filter again. I added crankcase stabilizer and ran for 5 minutes. The oil looked OK.
I'm ready to put her back into the water. How many times should I change the oil to clean out the crank? When should I add Auto-Rx? The engine is over 15 years old and was pretty sluggy from daily commercial use at low RPMs. But it sat with a solvent (gas) for over a week. Thanks!
I guess you could call this the unitentional flush. I would suspect that the great majority of the gasoine has already been removed from the crankcase. What little heat that you generated in the 3 minute run likely helped evaporate some of the gasoline as well as the new oil absorbing a good deal. I would suggest running the next oil change for perhaps 5 to 10 hours under somewhat easy operation. I am a little concerned about engine seals and gaskets. It is highly likely that the gasoline did very little with respect to cleaning hardened carbon deposits like ring packs for example. Especially with no circulation going on. I would suggest running a cleaning and rinse application right after your short 5 to 10 hour oil change interval under light duty. I would use 50 to 60 hours of dwell time for both cleaning and rinse.
