Seized Engine.

[Highlander]

I have a seized sv engine. I have the valves out, oil pump off and the 4 big end caps off. Still pistons stuck in bores. Tried petrol, oil, coke and still no joy. I do not want to hit the pistons with a wooden block as they are original size and I want to keep them. Ideas please. I wish I had found this engine two months ago as it would have saved me ££££, the big ends look as if they were re-metelled last week, valves look new as do the guides but enginge sludged up - nothing makes sense. Help. Alister Reid, Highlander.