Originally Posted by cindy2

I owned a Fiat Spyder that this was done with; with the exception it was disconnected altogether. It caused a buildup of pressure and eventually blew a head gasket; overheated the engine; and warped the heads. The engine had to be replaced. The car had only 5,000 miles on it at the time. Maybe it was a particular problem with the double overhead cam FIAT; but it could be an expensive test.