H,i was wondering if anyone could help. I changed the cam seals on my 6 last week. The car ran fine for a couple of days but then one morning I started it and it was making a tapping sound. It has never made this noise before and after doing some reading on here it sounds to me like a valve or lifter. When the timing was set all the marks lined up and the pins all fitted into the holes. Ive checked the timing again after the knocking but all the marks still line up. the car drives fine and doesn't feel sluggish. Could it be a lifter as some of the sealant may have fallen into the head and blocked an oil way in a lifter? Also when the cams were out the lifters weren't drained of oil could this affect it? Ive checked the crank pulley and its tight and also checked the plugs and there tight too. Any help would be greatly appreciated. Thanks