It appeared that my oil leak was coming from the rear main seal since the upper backside of the motor looks clean. I was too lazy to remove the tranny myself, and I got a good price from the dealer, so I took it in...No help...It still drips on my driveway. After much looking, I see a little wetness on the passengers side of the motor toward the firewall, but I can't see much through the wheel well. I bought some UV leak detector to put in the oil. Hopefully I can find it. Wish me luck....

I understand there's a problem with lower intake manifold gaskets leaking. Does anyone have any other ideas? Thanks.

 

My 96 4.0 has vavle covers that leak and manifold. I know someone who is a mechanic that said that the manifold gaskets go bad often.

 

I've replaced many valve cover gaskets on 4.0 in explorers for what it is worth.

 

I replaced my valve cover gaskets on my 90 4.0 about 6 months ago. What a pain. But I did it. It had sat for about year before I got it. My uncle wasn't able to drive anymore.

 

Update...The UV leak detector was a complete waste. It came in two packages, the additive that goes in the oil, and a UV "light" that comes with a pair of yellow tinted safety glasses. On the outset, it looked like it would work, but the light is way too dim to do any good. It's basically just two AA batteries powering a small lamp. It was so dim, I had to put the light about 2 inches away from the engine to see anything. I tried it at night too, but that didn't change anything. I changed my oil again, and with a bright light and mirror I took another look at the back of the engine. It looked bone dry. What I couldn't see was the right side, rear of the engine just under the #3 plug. (A/C evaporator plenum box in the way). I replaced the valve cover gasket on that side just for fun...no help. I could then see a little wet oil around the oil pan. Hmmm, maybe while driving the air is blowing the oil along the seam and coming out at the bell-housing area. I re-torqued the pan. 3 of the bolts were very loose, but the rest were tight. We'll see if this helps....wish me luck.

Edit 4 days later, Leak has slowed a lot, but small drip still remains. Looks like it's the pan.