|Re: OT: Seat-of-the-pants Crank Shaft Physics|
Message #4 Posted by Forrest Switzer on 22 Mar 2008, 7:37 p.m.,
in response to message #1 by Paul Brogger
I don't think this is going to be easy. Your method is trying to move all the pistons at one time unless you can unbolt them and separate them from the crank. Theoretically you would have the most leverage by working on a piston that is neither at the bottom or the top if you are really trying to turn the crank. Mid height places the lever arm furthest from the center of the crank at 90-degrees. But still you are trying to move all the pistons.
If you have the engine out and upside down, then I would try and unbolt the con-rods and the crank from the journals and see if you can get them all separated. You may be able to unbolt the pistons that are 90-degrees first and use a wooden hammer handle or something to reach up by the wrist pin and smack them to move them away from the crank.
You could also try some dry ice on each piston. Unfortunately you cannot see how they are stuck, but aluminium may have oxidixed in a manner that has swelled between the side of the piston and the sleeve. And you have no idea what type of rings are on the pistons and how bad they are rusted.
There are some penetrating oils sold by Kano Laboratories like Penephite that might help. Also, alternate heating and cooling might break some of the oxidation bonds.
Too bad someone didn't dump some thin oil on the top of each piston and lay the head back on it.
I dont know much about diesel engines but I assume the sleeves are installed with a heat/cool interference fit that would be near impossible to move.
Anyway, I think your best try is one at a time rather than all at once.