Car shuts down when hot, won't restart-HELP

A friend just purchased a 98 E320 and when the engine gets hot it shuts off and won't start. Once the engine cools down for 10 minutes is will run again untill it gets hot again.
Has anybody hear had this problem and have a fix. Thanks in advance for any help. - david

I had the same problem and it was water temp sensor that goes to the ignition module

Problem ended up being a bad crank shaft sensor...