Evinrude 3 hp 1947 ? 1 cylinder dead-intake crankshaft valve?

[moonlight]

I have a outboard with one (lower) cylinder dead.<br />It has spark, It has compression<br />and I think it's not getting gas in that cylinder.<br />I can blow air out theexhause, and through the reed valve out the cylinder, so it's not blocked.<br />The "reed" valve on the output of the carburator looks clean and nice.<br />I have not been able to take apart the crankshaft portion of the motor. I can see a "spiral" <br />looking thing through the reed valve port. I think there must be a way for the cylinder to close<br />off and create vacuum to pull the gas in. <br />Does anyone know if this is true? <br />It's not clear to me how to open the crankshaft area, even after pulling the flywheel, there's<br />stuff on top that looks like it's press fitted on. <br />Am I on the right track?<br />Advice? comments?

 

[JB]

Re: Evinrude 3 hp 1947 ? 1 cylinder dead-intake crankshaft valve?

Yes, Moonlight, I think you are on the right track.<br /><br />There is a cover over the bypass from crankcase to the scavenging ports. I think the gasket is leaking or even missing. That would prevent the crancase from drawing a vacuum to bring fuel/air in and from making pressure to pump it into the cylinder.<br /><br />If your reeds are sealing properly and you have good spark, something is preventing the scavenging pump action of the piston and crankcase. The bypass cover is most likely, but you may also have blown a crank seal.<br /><br />Good luck.

 

[almost retired again]

Re: Evinrude 3 hp 1947 ? 1 cylinder dead-intake crankshaft valve?

Hello Moonlight,<br />No one else has answered your post, so I'll try to respond. If you have taken the carb. off and can see the reed valves you souldn't be able to see past them. Crankcase pressure pushes them closed, and crankcase low pressure pulls them open allowing the fuel/air mixture to be pulled into the crankcase, and thru the intake ports to the top of the cyls. I'm not positive, but I think that you can remove the reed valves without seperating the crankcase. What I've just said is true on Johnsons/Evinrudes, but if it's a Mercury you will have to seperate the crankcase halves to get to them. They are installed on the crankshaft.<br />Good Luck

 

[JB]

Re: Evinrude 3 hp 1947 ? 1 cylinder dead-intake crankshaft valve?

I resent your smart alec remark, ARA.

 

[moonlight]

Re: Evinrude 3 hp 1947 ? 1 cylinder dead-intake crankshaft valve?

Dear JB,<br /><br />Great! Good to get confirmation. The only thing I'm unsure of is how to open the crankcase up. There's a ring on top, that I"m not sure how to get off.<br /><br />dear almost retired,<br /><br />Thanks for the reply. On the evinrude, the reed valves come off easily, and I removed them. That's how I could see past them.