Re: Mercruiser 470 pressure test
Bad cam seals might not show up on a pressure test. AF would get into the crankcase under some pretty specific conditions. The engine would need to be running which would pressurize the coolant, BOTH seals would have to be bad AND the water pump weep hold would need to be plugged, which would result in coolant leaking past both seals under pressure into the crankcase. If the weep hole is clear, coolant leaking past the first seal would dribble out of the weep hole rather than be forced past the second seal into the crankcase. So make sure the weep hole is clear (toothpick or wire inserted into the hole) and if it is clear and no coolant leaks out when the engine is running your cam seals are OK.