My 2001 F150 had been having a slight miss at low throttle when climbing a steep hill. It never was bad enough to set a code, so I figured I'd just order a set of the Global Automotive coils off Ebay. That would be cheaper than paying the dealer $150 to tell me which coil was failing. I thought I'd do the plugs too, and it turns out that it still had the factory plugs in it! 210,000 miles on the plugs! Anyway, I've got the new plugs in, torqued to 14 ft. lbs. per the Haynes manual I've got. I still need to put the coils back on the passenger side. Thanks to the very helpful tips on here, the job really wasn't half as bad as what I thought it would be.
But here's my question: There was oil in three of the four plug holes on the passenger side of the motor. It looks like a valve cover gasket leak to me, but I asked a mechanic that I've had do work for me in the past, and he said it was probably a bad head gasket. $800 - $1,200 was his estimate. I've looked the motor over, and for the life of me I can't see how a head gasket leaking oil, would end up getting oil in the spark plug holes? Is this possible? From what I can tell, the plugs are well above where the head meets the block. Am I wrong?
No, I'm pretty sure it was oil. It was thick like oil, not thin like coolant/water. Plus, the valve cover on that side is very oily/greasy looking. The driver's side cover is nice and dry. And I looked the heater hoses over very carefully with a worklight and mirror and couldn't see or feel any leakage from them.