Head gaskets and crank seals

[Anonymous]

Hi Stanley, I will try to find an article on this subject in an old copy of the Outboarder. Listed in the article are the crankcase casting numbers of the motors affected. Check back a little later today.

[Anonymous]

Hi Stanley, what I could find was the article written by R.A.Hawie in the July 1979 Outboarder pages34-40. This article was about the A50’s big brother, the K50 and later K series motors. On the K motors the crankcase sealing rings were introduced on the 1938 models. On the A50 and later smaller sized A series motors, this update never happened because none were produced after 1937. I double checked my info. by looking in the parts catalogs covering the A50 and up to 1937 model A motors and no crankcase sealing rings are shown. I have a K50 that was very hard to start with a cold motor, and if I did manage to get it running from a cold start you would have to keep the rpms up or it would die and you could not get is to restart hot. I fixed it by finding a donor KA38 motor built in 1938. I replaced the original crankcase with the one from the KA38 that came with the two sealing rings. After that it was a very easy starting and great running motor. But the A motors never had this update, so your option would be to try a crankcase from another motor. The newer the better and maybe less wear. Ok , so how to test for this? Check for and eliminate all other causes before blaming a worn crankcase. Check for spark using a tester that tests for spark plug under high air pressure. Check compression using a gauge. Take the carb apart and clean it and then clean it again and check all orifices for being clear. Also with the fuel line off the carb open the fuel pet cock and check for fuel flow. Reinstall the carb., connect the line to the carb. and with fuel in the tank and the gas cap vent open and did you check that the vent hole in the cap wasn’t plugged? Now test for fuel, by setting choke to full and roping over motor 10 or even 20 pulls of the rope with the plugs installed. Remove the plugs, and check to see if they are wet with gas. If you have good spark by the test , if you have a good compression reading on both cyls. and the plugs are dry THEN I would blame the crankcase.

[Anonymous]

Something else you could try as a last resort. Change the mix from 16to1 to 8 or 4 to 1 using Shell aviation oil 80w which is equal to the car rating of 40w and using this you may get it to run as a test. You must mix this thick oil well as it was never made to mix easy as TCW3 oil is .

[stanley]

Thanks for the lesson.I am a new member and this is my first project.I’ve got experience with other machinery,but none with outboards.These answers are a big help.I’m sure you’ll hear from me again,hopefully with a good report.

[Anonymous]

Hi Stanley, what I forgot was to explain what was happening in side the motor. This applies I think to any alternate firing two cyl. outboard. If you have a poor seal at the crank between the two crankcase halves of the two cylinders the fuel charge is pushed back and forth past the center main instead of through the transfer ports to the top of the combustion chambers where in can be burned and or it is not being sucked out of the carb into the crankcase to begin with.

[need2fish]

Comments not related to gaskets, but to hard starting: I have a K-70 and a K-50. Both were suffering from hard starting, especially when cold. Carb/Ignition were not the problem. In an effort to track down the entire “food chain” of combustion I found the relatively small exhaust opening in the bottom of the head/cylinder block and the portion of the leg where the exhaust makes a 90degree turn were completedly carboned up. Reaming both portions of the exhaust path improved both starting and acceleration.

[Author]

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