Motor shot on 380SL?

Hi guys...I am new to Mercedes, I have always been a BMW guy. Anyways, my girlfriends dad has a 1983 380SL that we went and attempted to take out of winter storage today. Here is what happened, and we think his motor is shot. Let me start out by saying this car is mint, it has 100k miles but looks like a 20k mile car. He has owned it for 6 years and said all it needed was an oil change. Sooo...today we hooked the battery up, and it struggled to start. Must have taken 10 or 15 minutes to finally to get it to start. During this time, it "burped" smoke out the carb a couple times, I wasnt sure if this was normal. So finally it stayed running for more than 2 or 3 seconds, but only emitted the harshest sound I have ever heard in my entire life. It sounded like someone was inside of it with a bat just baging to get out. Realisitcly, it sounded like a chunk of metal was on top of the piston slamming into to head. We rolled it outside, and let it sit for a while before we tried it again. Then someone noticed a huge puddle of oil underneath it. I checked, and although it looked like oil, it was green in color and did not smell like oil. I checked the dipstick, and it was fine, in fact it was overfilled. The car will run, but it makes that god awful noise, it sounds nothing like a motor.

Facts...engine has oil, oil puddle on the ground, oil looks greenish, and is coming from the backside of the motor(near the firewall) huge banging, sounds like a metal chunk on top of piston. Anyone got any ideas?

Maybe a crack block with anti freeze leaking in to the oil is the green color cause. But then again if the block is cracked the car probably wouldn't have started. You said the battery had to be charge, just wondering how long the car sat? Also, was the car outside or undercover? Also, I'm an ex BMW guy, I like it much better over here, just kidding welcome, hope the boyz here can help ya out.
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A friend suggested that it could be the timing chain? Its hydroulic and it takes a minute or two of running to get the fluid moving again?

DONT RESTART THE CAR! I am sure running it will cause more harm than any good my guess is the timing chain broke if u are lucky u have not already totaled the engine!

Ok...but how would the car turn over and run without the valves? Also, is it possible for a chain to break during storage? Just curious...it will be going to my friend who is the head of the service department at the local Mercedes dealer tommrrow, so we will find out.