Water in the oil

[Lipan Man]

I bought a 98 Explorer with a OHV 4.0 a few months ago and while having my oil changed the technician said that a small amount of water was present when he removed the drain plug. The drain plug also had a small amount of the milky sludge on it but the oil cap on the valve cover is clean. This was the third time I changed the oil since I bought her but the first time any water was noticed. She has 150k miles and runs great. I have no experience on a 4.0, is this the beginnings of a head gasket failure or maybe (hopefully) something else? Can I tell without removing the heads?

 

[Batt54]

I had a simular problem with my 97 SOHC 4.0L. mine was almost worse case senerio though.. both heads were warped. in talking to a couple techs at the Ford service center they had had a few of the OHV 4.0L in with cracked heads around #4 cylinder. I'd recommend getting the coolant system pressure tested, and maybe a pressure test on the cylinders themself to see if its exchanging fluids. what does the coolant look like?

 

[Lipan Man]

The coolant looks good, it is clean and full. I think I will check around and find a garage that can do a pressure test on the coolant and cylinders. That should let me know what I need to do. Thanks