I'm looking at buying a '77 240D automatic and i know a broken car when i see one, clearly the timing chain has broken on this thing and it will need replacing, but thats not my question, my question is: why did the timing chain break opena holenear the top of the valve cover, through which i can clearly see the chain? the hole is on the left side of the cover (right if you're looking under the hood)

 

Because the loose end of the chain flapped up there and hit it. Personally, unless it was for parts, I would not buy this car. There are so many old cars in good condition available that buying a really broken one that needs major repairs just isn't worth it.

 

and if i get it for free?

 

Look into what it will cost you to repair it. I still think you could get a running one cheaper, so unless the body and interior are simply immaculate, I would probably pass. You could have piston and valve damage lurking in there as well.

 

I'm currently enrolled in auto shop classes at the local college, so i could do a valve job there without much trouble and for no charge. I would tend to agree with you thoughif the thing needs a complete rebuild

 

If you can get it for free and want to play around then go for it. Iwouldn't spend any money on it until I was sure that the valve train and pistons are alright. If it isn't need parts it out and sell what ever is left for scrap