I swear that this Ford Explorer is cursed! It started with it blowing blue smoke so we decided to rebuild the 4.0L V6 OHV. During the rebuild I noted some cracks in the heads and mentioned it to the machine shop but they said the cracks were only between the water jackets and would be fine as it was common with the cast iron heads.. With it all together it dumped coolant into the oil pan. Come to find out the cracks actually extended beyond the water jackets and into the bolt holes. Probably from the previous owner using an impact tool on the boltsNot to mention the transmission issues.... We ordered new cast iron heads and checked for true on the engine and heads when they arrived. As a couple of the gaskets were damaged from the machine shop rebuild kit, we replaced them. After basically tearing the engine completely apart, save the pistons and crank/cam followed the recommended torque values for the heads/intake/rockers. What was odd was the intake manifold to head gasket was a one piece item with pre-established center portion and rubber seals fore and aft. I was not sure about the part as each one I found for the 2001 was a two piece design. The clerk reassured it was fine. After getting it together again getting coolant in the rear tail pipe and a slight oil leak as well as coolant leak, to the rear leaking down, either out of, or out of the transmission weep hole between the spacer of the automatic. Fortunately there was no coolant in the oil this time but a quick smell and taste of the residue from the exhaust was sweet.

My instinct says either the intake or rear main seal for the oil and either the gasket for the intake or the intake itself that might have a crack...

Okay so those are my woes with this beast, that might end up a flame shortly.... So questions...

Oil leak location? Could it be the rear main seal? Most of the original gaskets were possibly damaged and some of them like the oil pan gasket, were actually bent. Pretty much all but the rear main seal and cam seal, exhaust manifold gasket were replaced. Or could it be the intake manifold gasket that was a one piece?

Has anyone dealt with he one piece intake manifold to block gasket?

Could the intake or intake gasket be leaking the coolant into the exhaust? Although torqued to the appropriate inch pounds and foot pounds in sequence could they still be loose or might the gasket be the wrong one? Could the coolant system be over pressurizing?

Thank you in advance!

 

I don't know if this is the problem with your engine, but it is something to consider.
If the replacement heads were resurfaced , they will sit lower than the original heads and so will the intake ports. Usually the mating intake needs to be resurfaced so the ports and gaskets line up properly. It is easy to overlook especially if you are engrossed in other work.

 

Thank you Hanky! I will certainly take a look at the heads. I do not trust, at this point, anything the machine shop said after overlooking the crack in the old heads. I also do not trust anything that was original on the vehicle. :P