So we picked up an MD for scrap value that is complete but stuck. It has been soaking for a week with Kroil in the cylinders. We decided to put it inside and pull the valve cover. All of the valves seem to work. We pulled the rocker arm and thought we would push some air into the cylinders to see what would happen. The air either gurgles or pushes out the exhaust. I have read that the valves are different on this tractor but it seems like if all 3 valves are closed that there would be no where for the air to go unless the head gasket is blown or head is cracked which I guess is common but I would not expect that on all cylinders. The tractor was running when it was parked and there was no oil in the water or water in the oil. Does anyone have some thoughts on this? What I am looking for is what is different about the MD as I have done this on other engines to test for leaks. I hate to pull the head but it is looking that way.
Thanks

If it ran when it was parked I would try to get it started after it is freed up.
The 3rd valve just opens up a cup that increases chamber volume that lowers compression and if I remember right the spark plug is in that cup area.

There is probably material in the valve seat that is holding the valves open a little.
The tractor will free up (my opinion, I unstuck the one I owned over a period of 3 months) When it frees up. (assuming the valves are not stuck) pull it down the road to get oil pressure, then go for the gas side start. Jim

It just came to me ... how are you putting air in?
If you are using the spark plug holes you are probably hearing some noise from the air pushing past the gas start valves.
If you are going in through the injector holes ignore what I said.

I agree with what Jim said.
There may be trash built up on the seats from sitting so long.
That should clear up some with some running.

(quoted from post at 09:46:40 11/12/11) When it frees up. (assuming the valves are not stuck) pull it down the road to get oil pressure, then go for the gas side start. Jim

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I'll add to that. If it gets towed for pressure, spark plugs out and switched to gas. Lower end bearings are very expensive. I've seen several that didn't survive the ordeal.

(quoted from post at 17:11:16 11/14/11)

(quoted from post at 09:46:40 11/12/11) When it frees up. (assuming the valves are not stuck) pull it down the road to get oil pressure, then go for the gas side start. Jim

Click to expand...

I'll add to that. If it gets towed for pressure, spark plugs out and switched to gas. Lower end bearings are very expensive. I've seen several that didn't survive the ordeal.

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I don't follow. What will damage the bearings? (I think I know...but I don't want to guess out loud.)

(quoted from post at 20:47:03 11/14/11)

(quoted from post at 17:11:16 11/14/11)

(quoted from post at 09:46:40 11/12/11) When it frees up. (assuming the valves are not stuck) pull it down the road to get oil pressure, then go for the gas side start. Jim

Click to expand...

I'll add to that. If it gets towed for pressure, spark plugs out and switched to gas. Lower end bearings are very expensive. I've seen several that didn't survive the ordeal.

Click to expand...

I don't follow. What will damage the bearings? (I think I know...but I don't want to guess out loud.)

Click to expand...

The extra pressure from compression to the dry bearings.
It will be hard enough with the stuck pistons.