« Reply #3 on: April 26, 2012, 08:06:55 AM »
'Tis I of the diesel dustbin. It will penetrate a seized piston. The chief advantage is it penetrates all the rusted fasteners and so many more of then undo without hassle. Then you have to recall I am a committed dismantler of long unused engines.
It does depend on why the engine is seized. A mechanical seizure is dependant on the breakage. Just having a unit with no use is normally rust binding. That will often go with a soak and perhaps a cycle of heat to break the bonding. The worst is a used but left engine as the rings will often have petrol/carbon crude round them. If the rings rust on the inside they are forced out onto the cylinder with the organic gum making a very effective barrier to any form of treatment. Even heat really makes very little difference.
I just failed to part a Sachs 175 unit. Looked fine but the piston would not clear. I gave it all the usual treatments. I got it moving with a block of wood and a mallet but it then got to BDC and that was enough constriction to stop it. Once again with the mallet and clearly I was hitting it to hard as one fin just shattered from the vibration. The piston itself was no good by now so I gave it to Russell Church as he wanted an exhaust thread to mount on a jig to make Messerschmitt Exhaust systems, available shortly form Russ. Russ reported that even though he put a band saw round the piston thus relieving the pressure some it still refused to budge. I await the mutilated remains on the end of my crank next time we meet. Sometimes the little swine will not come out and that's all there is to it.
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