There's a young man who lives a block away from me who owns a 1980 240D, which he's been running on veggie waste oil. Car was running fine, but then suddenly one day it would not start. Turned over, but would not start.

Since the starter was balky, he took it out and had it replaced with a rebuilt, which turns nicely; he also replaced the battery. After removing the valve cover to check valve clearances, we discovered that the starter engaged, but the valve train would not move.

Could it be a broken timing chain? I thought this unlikely, given the double row chain. My knowledge of MB diesels involves all maintenance procedures, but I have never delved into the inner workings of the engines.

Any input would be appreciated.

Joe B.