2006 4.0 oil leak up top

[ksmith]

Thought I'd come to you guys for some insight and see if anyones had a leak like this. Wife's explorer started leaking oil on the driveway. Upon further inspection I could see that it was coming from up high on the back of the motor and leaking down the bell housing and out the bottom. So I go to the front of the motor and remove a bunch of leaves from top of engine under intake and the oil is puddled all across the top of the block between the heads. Of course I can't get in there to clean it up. So I remove the intake manifold and try to clean it all up. So I highly doubt that its a head gasket leaking oil like this up high because I don't think the oil flowing back down the heads is under any pressure. Oil looks clean, coolant looks clean, and truck runs fine. I checked the valve covers real good and there's no sign of them leaking down. So I'm left with two options I think. The oil pump drive assembly gear slides down in from the top of the block towards the back. There is an o-ring on this and I believe this part is under pressure and could be the source of the leak. The only other thing up there is a knock sensor right in the middle. I don't believe it's under pressure but I could be wrong. So these are the two things I'm thinking. Which one would you guys bet on? Should I replace both and just be sure? The oil pump gear has an easy o-ring to replace so I will do this reguardless. But I'm not sure about the knock sensor. Thanks for the help guys. I tried researching this for several days and just saw people with valve cover leaks. So I thought I'd post and share my problem for anyone else trying to figure out an oil leak up high like this.

 

[ksmith]

Here's a few pics of what I'm working with. Note that I already removed the oil pump drive gear and that's why the screw and hold down clamp are missing from the picture. I was in the process of removing it when I took the pic.


https://www.flickr.com/photos/113047805@N06/11668556583/player/deb32ca434

http://www.flickr.com/photos/113047805@N06/11669104266/

http://www.flickr.com/photos/113047805@N06/11669108056/

http://www.flickr.com/photos/113047805@N06/11668319325/

 

[Flag Gibby]

Run a compression test and see if you have leak down issues on a particular cylinder and that might help you get closer to the problem, but I really don't think it will help you much in this case.
A quick way of testing/seeing where the leak is at is to pressurize the crankcase on it and then put some smoke into it and see where the smoke comes out. In other words, pull a spark plug, use that point to pressurize the system up to a couple of PSI and then using a switching valve of some sort introduce the smoke and see where it comes out.

So ksmith, you are suggesting/showing that the issue is the oil pump drive gear?

 

[ksmith]

Yeah that's what my best guess is at this point. I think I'll put a new o-ring on the oil pump drive gear, clean everything up real good and then put it back together. Then crank it up and see what I can tell. I should be able to see where the leak is coming from if it still does it. I was just wondering if anyone had heard of the oil pump gear, knock sensor, or head gasket leaking on top of the block like that. Maybe save me some trouble of pulling it back apart. Thanks for the advice on the compression test.

 

[Flag Gibby]

Yeah, never seen oil come out of those areas before unless something was not bolted down correctly after having work done on it.

 

[ksmith]

Well it's definitely not the knock sensor. The bolt for that doesn't actually pierce the block. It just sits on a flat surface. I cleaned up the intake manifold today before I put it back on. I'm even a little more puzzled now because there was oil on the intake gaskets. There's six separate gasket rings and they all seemed kind of oily. The intake tubes themselves had a very tacky black residue inside them. I don't know what would make it tacky and gluey like that. Any ideas?

 

[Flag Gibby]

The crankcase ventilation dumps into the intake in two different areas so the residue inside them is most likely from that.

 

[ksmith]

Wow, okay. Yeah I did a quick search on here and ended up reading for an hour about oil residue in the intake because of PCV. Seems like it has been an ongoing debate for years but very normal to see it there. Thanks.

 

[ksmith]

I'm having a tough time finding the torque specs for the oil pump drive gear and the intake manifold torx bolts for a 2006 SOHC 4.0.

 

[ksmith]

Well just as a follow up, I put it all back together with new intake gaskets and cleaned everything up real good. I replaced the thermostat housing while I was in there and of course the main radiator hose leaked a little so I had to shut it off and reclamp it down. Other than that I did not see any leaking oil. I let it idle for about 20 minutes and watched it real good then took it for a drive. When I got back I looked again and everything was still clean. So, so far so good. It still bugs me that I don't know for sure what was leaking the oil. But, we only had the car for a couple weeks before I noticed it and there's no telling what the previous owner could've done to cause that oil to be there. This site is great though, tons of great information. Thanks for the help.

 

[wallsofsound]

I just experienced the same thing after an oil change

I think the oil change guys put too much oil in and there is some type of oil pressure relief valve that causes this My truck never leaked a drop till valvoline did the oil change I wish I would have done myself . But Its cold here And I am old and tired.

 

[mark6637]

Bless you Ksmith! After long searches on forum and web, showing pictures of "that part behind the 2nd expansion plug" to TWO dealership parts departments and one service department team, no one told me "oil pump drive". In fact, two of my text w/ photos were never even responded to, leaving me stumped and annoyed. Then here, and presto, no more mystery part...awesome! My question though, did you indeed replace the o-ring (after market?) and just torque it back down as you said you were going to do, and if so, has the leaking stopped? That will be the last o-ring I purchase before all the other parts/o-rings/gaskets can start to be put back on (i.e. valve covers, injectors and their adapters, thermostat and housing, air intake, spark plugs and their wires, EGR, PCV, etc.) What a learning experience this project has become for a woodworker like myself. I have a newfound respect for automotive technology (if NOT for dealerships), but Hertz wants their car back, and I have a pool and weeds begging for my attention.