cylinder removal

JimNH said:

The grease gun poses no danger. Since the grease does not really compress as soon as the piston moves all pressure is off. It's much better than hammering away at it with wooden blocks. The pressure comes on gently and only enough to make it move.

Click to expand...

... but neither does the threaded rod method either.... but at least you can observe what is happening with the threaded rod method by looking into the cylinder as you turn the rod and you can feel the resistance on the wrench change as you apply pressure... if the cylinder breaks free.

With the grease method, how do you know which piston is stuck? As I said previously If you push on a free piston and the other one is stuck solidly, then aren't you cross loading the crankshaft and connecting rods??? With the grease method, Do you actually know how much force you are using?

I'm also interested in the explanation of how it's done for diesel engines because if they don't disconnect the crankshaft then they are potentially using the crankshaft and connecting rods to apply force to stuck pistons... (I'm actually curious enough now to google it )

http://s40.radikal.ru/i088/1108/2b/4b1a8a077aea.jpg
maybe this will come handfull

o0norton0o said:

JimNH said:

The grease gun poses no danger. Since the grease does not really compress as soon as the piston moves all pressure is off. It's much better than hammering away at it with wooden blocks. The pressure comes on gently and only enough to make it move.

Click to expand...

... but neither does the threaded rod method either.... but at least you can observe what is happening with the threaded rod method by looking into the cylinder as you turn the rod and you can feel the resistance on the wrench change as you apply pressure... if the cylinder breaks free.

With the grease method, how do you know which piston is stuck? As I said previously If you push on a free piston and the other one is stuck solidly, then aren't you cross loading the crankshaft and connecting rods??? With the grease method, Do you actually know how much force you are using?

I'm also interested in the explanation of how it's done for diesel engines because if they don't disconnect the crankshaft then they are potentially using the crankshaft and connecting rods to apply force to stuck pistons... (I'm actually curious enough now to google it )

Click to expand...

As I said earlier in the thread, the tractor collectors generally know which cylinder or cylinders are stuck due to water ingestion from an open exhaust valve and pressurize that cylinder.

I have no objection to the threaded rod technique but if you're really curious as to how much pressure you're applying a pressure gauge teed into your grease gun (shop I worked in as a kid had a gauge on the air powered gun) and a little math will tell you exactly how much force you are applying. Keep in mind that you'd be forcing a lubricant into the rings and all around the piston. Yes, you can feel that you're wrenching tight with the threaded rod but how much pressure are you applying?

I've only used the grease gun method on stuck brake pistons - a lot of them, it's amazing how much water gets into auto and truck calipers and the corrosion it causes to cast iron and aluminum.

I have old tractors and thus frequent forums where the method is discussed and have friends who've actually used it and all report success.

As I recall, the peak pressure during combustion is approaching 500 to1000psi in a gas engine under heavy load. You could google that because my memory isn't all that good. Anyway, with a 3" piston that would equate to as much as 7000lb of force. If a stuck piston doesn't move with that much force applied......