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Stuck valve

Thu Mar 11, 2004 9:25 pm

A year ago we purchased two cubs: a 1972 and a 1948. The majority of the work has been done on the 72 because it was already running when it was purchased. Recently, I tried to start the 48 and had no luck.I discovered an exhaust valve seized in the open position on cyl. #2
I was wondering if anybody has had any luck freeing up valves without removing the head.I know it is a long shot but any encouragement would help. Thanks!

Thu Mar 11, 2004 9:48 pm

You could try and lubricate/clean through the valve cover area. If your valve is not too bad, you can try to work it up & down against the spring with a penetrating lubricant of your choice. Be careful not to scratch the shaft surfaces. If it is badly rusted or blocked with tons of carbon, you may have to remove the head for a proper cleaning or overhaul.........

Thu Mar 11, 2004 10:24 pm

I had good luck freeing up four stuck exchaust valves on a 1948 cub by removing the spark plugs, and removing the valve cover behind the carburator. Some of the lifters were dry and hanging also. Used lots of PB Blaster penetrate and an L shaped allen wrench through the spark plug hole. Set the L part of the allen wrench on top of the stuck valve and a few light taps with a hammer will in most cases free up the stuck valve. Once down you can pry the valve back up with a screwdriver between the lifter and the valve stem. ---CAUTION---- make sure that the lifter associated with the valve being worked on is not being held up by a lobe of the cam when doing this procedure. May need to turn the engine crankshaft occassionally to move the cam lobe out of the way. Once the valve, and or lifter begins to move it doesn't take long for the Penetrate and the back and forth movement to have things moving smoothly again.
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