just finished valve job on my 92 300e, now there is a noise on the right side of the motor, sounds like an exhaust leak, I'm guessing valve train noise, used a mechanics stethoscope to pinpoint noise, it is louder at the rear of the valve cover, cyl#6, at diassembly rockers and shims where marked and put back into place. The motor runs smooth otherwise, any help would be appreciated, thamks!