Algodoo

I found you problems, and got your engine working quite well. I have saved the scene if you want it. Timing and everything else seams good, but had to change the things below.

1. Reduce friction of pistons to 0. Car engines use oil to reduce friction.

2. Increased the density of the pistons and the piston shafts (engine block) so the pistons stayed in them middle and ran smoothly. If the density is to low things become too soft and collide threw each other.

3. Thickened the bouncing bars at the top to stop them from going threw there stopper; same thing as #2, overall strengthening.

4. Played with the dampening and strength of the springs (lowered). I noticed one popped off and span around the screen very fast LOL.

5. Set the density of the explosions to 2.0. This helps stabilize the engine, and would allow you to detach it from the background without it flying around.

6. Increased the diameter of the flywheels so there was more momentum (Hold shift while using the resizing too, so they stay round)

7. Removed the piston rings so I could adjust the pistons.

Hey Thanks! I made a new one, before I read your Comment.
Try it, it's strong and runns clean!