BMW Repair: 1990 735i suddenly stopped on the road, cranks but wont start., coolant system, temperature gage

Question
E32 (1990 735i Series BMW)
I drive a 1990 735i series BMW.  The overflow tank sprang a leak, so I parked it for a week until I could replace it and refill the coolant system.

After about 40 miles of interstate driving, the car's temperature gage suddenly jumped from normal to near the red.  The car shuddered and then just stopped (electrical worked, but the engine stopped itself).  

After letting the car sit for a few hours and cool down, I tried to start it again and while all the electrical stuff lights up and it sounds like the starter's  running, it doesn't sound like the mechanical part of the engine is "engaging."

I didn't see any damage visible from above the engine (I couldn't crawl under since it was on the side of the interstate), and a friend suggested the camshaft is destroyed.  Do you have any suggestions about things to check and the level of mechanical in-depthness required (I'm a college student limited to hand tools and a parking lot)

Thank You,
Michael

Answer
I would doubt that the camshaft broke,removing the valve cover would determine if it was broken of not.Overheating the engine is always bad for a car.I would do a compression test to see how bad it may be,wether a cylinder is down or not.By removing the valve cover you can see if the cam is bad and also if it did jump timing(has a timing chain).If it did jump the chain,I would have to say it is not good as all the exhaust valves probably are bent.Remove the valve cover and sheck it out,let me know