Old 50's model Johnson

[tailintidecharters]

I recently bought a 5hp johnson and it runs great but then after about 5 min it makes a noise like pressure from and air hose a few times and then dies. I was wondering if anyone had any ideas on what that could be. Also where could i get a manual on this motor. The model number is a TN 26. Thanks for all of the help!

 

[tashasdaddy]

Re: Old 50's model Johnson

welcome, no idea, but here is manual info.
http://www.outboardbooks.com/index.cfm?fuseaction=models.main&year=1950&ID=55025

 

[Chinewalker]

Re: Old 50's model Johnson

I think the sound you're hearing is a lean sneeze out the center main orifice. Those old 5s have a mixing valve for low speed adjustment that operates off an air intake and rotary valve on the crankshaft's center bearing. If you get a lean condition it may sneeze out that bearing. Could be due to a carb issue that isn't apparent upon start-up and only presents itself after running a few minutes...
- Scott

 

[TN-25]

Re: Old 50's model Johnson

Are you remembering to open the vent on the filler cap? That's the little knurled part on the filler cap. It needs to be open when in operation to allow equalization of air pressure in the tank. Also remember when you shut down to close it and the fuel petcock on the starboard side of the motor .

They were Johnson's most popular little motor through 1953. They are about 1 generation too old to be a practical motor to restore, but they do run well and idle down beautifully when all is set properly on the low speed rotary valve and the high speed needle AND the motor doesn't have excessive bearing clearance. They don't have the powerhead and transom swivel bracket rubber isolation of the 1954 and later 5?, so they relied on the rubber tiller handle and spring within to isolate the pilot's arm from numbing vibrations.

Originally those motors called for a 16:1 gas / oil mixture but you can safely run it on a 24:1 mixture with modern TCW-3 oil. Synthetic will reduce the smoke somewhat.

I just had dad's 1950 TN-26 completely restored. I've now got way more into it than anyone would ever pay, but I don't care. I wanted it cosmetically and functionally restored. I'm happy with it.

 

[F_R]

Re: Old 50's model Johnson

The little bent rod that goes into the hole where it is spitting from is the idle mixture adjustment. Give it just a little tweak to the left to enrichen the mixture and it should stop the sneezing and spitting.

 

[1946Zephyr]

Re: Old 50's model Johnson

Those are the funkiest designs on those old Johnsons. How the hell did they come up with that? The carb mounted on the exhaust plate?? pretty wild.

 

[F_R]

Re: Old 50's model Johnson

Maybe funky, but it's hard to complain about one of the best selling and most reliable motors that Johnson ever built.