No carbon on piston head???

[rcrawley]

I have a 2000 Explorer with a six cylinder. Last spring totally lost power to the point that had trouble going up any amount of incline. Had it looked at by a mechanic. He measured only 40# compression in #4 cylinder.

Due to the labor cost, chance that was serious problem and not that hard to remove a head I had him bring it back home.

Finally got around to removing the head. There were two streaks of what lookes like water contaminated oil on the inside of the valve cover (not above #4) and the piston head has absolutely no carbon buildup. There is also "sludge" buildup in the intake. There is no obvious damage to the valves.

Any ideas?

 

[koda2000]

You need to have the head checked for cracks at a machine shop (by magnefluxing or other method). Cracks can be very had to see with the naked eye. The 4.0L OHV heads are prone to cracking. Sure sounds like you may have a cracked head.

Super clean spark plugs, valves and pistons are another indication of water intrusion. It steam cleans parts.