There are 2 other seals under the timimg cover which fail as frequently as the cam seal. Unless you removed the cover it is not possible to know which is leaking. These seals should normally get replaced all at once as a preventive measure while doing a timing belt change.

Don message was not referring to the rear main seal, he is referring to the plug at the rear of the valve cover which often leaks or worse still blows out under crankcase pressure.

As Don says a leak on the air intake bellows tube would not affect crankcase pressure. Is that the plastic pipe you refer to? Make absolutely sure the small brass nipple for the flame trap vacume line is clear. You can "feel" for crankcase vacume by applying your palm over the oil filler opening, in a few seconds a very slight vacume will build, you will feel it release when palm is removed. Do this before engine gets hot.

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David Hunter