Frozen Cub Engine

Mon Oct 07, 2013 1:35 pm

This is a follow-up from a year ago, now that I finally got time to do some serious work on the tractor. This is a 1947 Cub that quit running and needed a new magneto. It has always been maintained and garaged since I have owned it for the last 30 years. While manually turning the engine to time it, it developed a bind and finally froze solid.

I have removed the starter, generator, fan, head, oil pan and can find no reason for the bind. The internal parts of the engine were clean and lubricated when I removed the oil pan with very little sludge in the bottom. I gently pried each of the connecting rods side to side to see if I could detect a bind and the same with the crankshaft. You get a few thousandths movement in all locations, seeming to indicate that they are not bound up. The engine looks like new on the inside.

The only other moving parts are the hydraulic pump and governor. Can either of these cause a bind? I'm out of ideas!

Thanks,
Ed

PS I've tried rocking it in gear and coasting down an incline, but stopped short of towing it, for fear of more damage.

Re: Frozen Cub Engine

Mon Oct 07, 2013 2:31 pm

Yes, could be either the hydraulic pump or governor, perhaps the oil pump or trash caught between the crankshaft and idler gears. Some listed are highly unlikely. My guess is a valve suck shut or partially shut.

Question. Tractor rolls when out of gear? Rolling the engine by hand backwards, is the engine locked up or can you get part of a crankshaft revolution? Tractor in 3rd gear, tried rolling the tractor backwards? PTO disengaged?

Re: Frozen Cub Engine

Mon Oct 07, 2013 2:37 pm

Since the problem apparently started when the new magneto was installed, I would remove the magneto (if you haven't already), and see if the engine will turn. It coasts OK with the clutch is pushed down?

Re: Frozen Cub Engine

Mon Oct 07, 2013 3:28 pm

You mention the fan was removed. Does that include the fan hub or fan belt?

Re: Frozen Cub Engine

Mon Oct 07, 2013 5:31 pm

I have seen this happen whe a cub sets for a period of time. It is usually from mud wasp getting in the intake or can get in through the exhause. I would suggest that you try to turn the engine backwords,If it turns then you can bet there is junk in the cylinders..

Re: Frozen Cub Engine

Mon Oct 07, 2013 5:45 pm

Clark Thompson wrote:I would suggest that you try to turn the engine backwords,If it turns then you can bet there is junk in the cylinders..
ecbrewster wrote:I have removed the head.

Re: Frozen Cub Engine

Mon Oct 07, 2013 7:08 pm

If you haven't already, check the starter and make sure it isn't' jammed into the ring gear. Remove starter bolts and pull starter back to release it.

Berlin

Re: Frozen Cub Engine

Mon Oct 07, 2013 8:08 pm

Remove the hydraulic pump. Then try turning the engine.
Ed

Re: Frozen Cub Engine

Tue Oct 08, 2013 8:03 pm

Eugene wrote:Yes, could be either the hydraulic pump or governor, perhaps the oil pump or trash caught between the crankshaft and idler gears. Some listed are highly unlikely. My guess is a valve suck shut or partially shut.

Question. Tractor rolls when out of gear? Rolling the engine by hand backwards, is the engine locked up or can you get part of a crankshaft revolution? Tractor in 3rd gear, tried rolling the tractor backwards? PTO disengaged?


Engine won't turn forward or backward and does roll out of gear. EC

Re: Frozen Cub Engine

Tue Oct 08, 2013 8:19 pm

Next step.
ScottyD'sdad wrote:Remove the hydraulic pump. Then try turning the engine.
Ed
Check to see that the nut and lock washer as well as the gear are still on the pump.

Following step, if that's not the problem, remove the governor.