Most Head gasket failures are between cylinders, so effect compression on two adjacent pots. Dropped valve maybe. Guy Dave Yealy Sent Possibly a bad / leaking head gasket. Only a guess.... Dave No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.16.6/1150 - Release Date: 24/11/2007 17:58