Autopsy of a Failed 4.0 SOHC

[96firephoenix]

Just going to start this here. I've got a spare dead engine that I can use for a reman core, and just for grins and giggles, I'm going to tear apart the one that is coming out of my explorer. Pictures will be added as this progresses.

Parts will be sent to scrap, so it is kinda worth my time to separate steel/iron from aluminum anyway.

The initial problem:

• Previous owner broke one of the bolts holding the thermostat housing and destroyed the tang on the head that secured the bolt. T-stat housing would not hold a seal.
  
• At some point, this engine got a headgasket leak from combustion chamber to water jacket. Burns coolant at startup and coolant reeks of gasoline.

Further problems I've uncovered tearing this engine out and down:

• Knock sensor leads were missing the insulation roughly from the last centimeter. (I think this was the cause of some of my issues).
  
• PCV has been feeding oil into the intake for quite some time, and needs to be replaced...
• Tensioner pulley is shot (not a big problem, but still adds to my RockAuto bill).

 

[96firephoenix]

Finally tore the engine down into steel/aluminum piles for the scrap yard last weekend. Turns out you can strip a 4.0 in about 3 hours if you don't care about little details like the parts being reusable afterwards, or not using an angle grinder to remove the timing chains.

Even if this thing hadn't blown both head gaskets (water in the two back cylinders), it wouldn't have lasted much longer anyway. The rear timing cassette fell out when I flipped it upside down.... without me removing any bolts on it.