1948 Cub won't turn two full revolutions with crank

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stoneridgecub
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Joined: Mon Jun 14, 2021 4:50 pm
Zip Code: 18092

1948 Cub won't turn two full revolutions with crank

Postby stoneridgecub » Mon Jun 14, 2021 5:50 pm

Have a 48 cub which was really tired 5 years ago. Parked it and figured I would get to some form of rebuild later. Last fall went to try to start it and realized a leak in exhaust pipe had filled #4 with water and engine was seized. Pulled head and filled cylinders with ATF. Did that about a half dozen times over the winter and spring.

This weekend I took a hand sledge and a 1" oak dowel and started hitting on #4 and #1 piston alternately . Moved! So I tapped them down to bottom of stroke and then took a hone to #4 to clean it up a bit (pretty rusty). Soap and water cleaned #4 a few times and then wiped oil on all of them.

Took the hand crank and started turning. Went almost two full revolutions easily and then STOPPED. #4 was almost at TDC on firing stroke according to Mag location. Then I turned the engine backwards by hand (moved easily) until it went almost two full Revs backwards and then STOPPED. Now #4 was at the bottom of stroke. So something is preventing me from rotating through #4 TDC in forward direction and from going past BDC in reverse direction. It sounds like a hard stop and I don't want to force anything with the hand crank

Tractor is in neutral, PTO disengaged, with the starter and Mag still in.

Haven't seen anything like this before, what am I missing? Any guidance would be appreciated. Thanks

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MiCarl
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Tractors Owned: 1944 Farmall H
1948 Farmall Cub
1994 Speedex 1631
Circle of Safety: Y
Location: Livonia, MI

Re: 1948 Cub won't turn two full revolutions with crank

Postby MiCarl » Mon Jun 14, 2021 6:00 pm

Every other revolution sounds like valve train.

I'd start by looking at the #4 valves since that's where you had water.
1944 Farmall H
1948 Farmall Cub
1994 Speedex 1631

Eugene
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Re: 1948 Cub won't turn two full revolutions with crank

Postby Eugene » Mon Jun 14, 2021 6:31 pm

MiCarl wrote:Every other revolution sounds like valve train. I'd start by looking at the #4 valves since that's where you had water.
You should be able to see the non stuck valves moving when you rotate the engine.

While there, lubricate the unstuck valve stems.
I have an excuse. CRS.

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SONNY
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Re: 1948 Cub won't turn two full revolutions with crank

Postby SONNY » Wed Jun 16, 2021 9:29 am

sounds like valve rusted shut to me.

stoneridgecub
Posts: 2
Joined: Mon Jun 14, 2021 4:50 pm
Zip Code: 18092

Re: 1948 Cub won't turn two full revolutions with crank

Postby stoneridgecub » Thu Jun 17, 2021 2:46 pm

Yes, #3 exhaust is really stuck. Tried spraying KROIL and letting sit, then tried heat on valve. So far nothing has worked.


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