i have two old 18hp flat 2s that when i try to run them spew rather forcefully out the intake and i dont think its a head gasket since i took them both off and they both looked fine.
1. how are these engines lubricated?
2. what would cause this other than a head gasket?
3. how do i fix it?
Check to see if you have gas in your oil and /or the oil is overfilled, it is probably coming from the carb. Result will be fuel/oil mixture is being forced through the breather into the carb.The float needle in your carb is not closing properly. This is resulting in fuel flowing nonstop from the tank, through the carb, into the cylinder, past the rings into the crankcase. Remedy, you will need to remove the carb and replace the float needle and possibly the seat, depending on which brand of carb you have. Oil will also need to be changed, as it is probably contaminated by fuel flowing past the rings. Some fools will say to just install a shut off valve in the fuel line and make sure you turn off the fuel after each use. If you forget, you will be back to the original problem. I always recommend fixing the problem right the first time, but make sure you read my signature.
Head gasket won't cause that problem on the old opposed twin. Spewing out the intake sound likes an intake valve problem. They a lubricated by splash caused by the crank and a oil slinger on the governor gear. If it is the intake valves you would have to take the valves out and shorten the length buy filing the stem off to adjust the clearance between the valves and the lifters. One way you might be able to tell is to take the heads off and with the piston at top dead center on the compression stroke and see it you can turn the intake valve. If you can you have less than 0 clearance.
Along the lines of what Rivets said, also check your fuel pump if it’s a vacuum-operated one. If it has failed internally and fuel can enter the crankcase, when the engine is shut down, gasoline could have filled the crankcase. Then when you try to start it, you’ll blow oily gas out the intake since it has nowhere else to go!
