RV Surgeon

A mechanic was removing a cylinder head from the engine of a class A motorhome when he spotted a well-known heart surgeon in his shop.

The surgeon was there waiting for the service manager to come take a look at his RV when the mechanic shouted across the garage, "Hey, Doc, can I ask you a question?" 

The surgeon, a bit surprised, walked over to the mechanic, who straightened up, wiped his hands on a rag and asked, 

"So Doc, look at this engine. I open its heart, take the valves out, repair any damage, and then put them back in, and when I finish it works just like new. So how come I'm paid so little compared to you when we're doing basically the same work? 

The surgeon paused, smiled and leaned over and whispered to the mechanic, "Try doing it with the engine running."