4.0 OHV oil leak.

[JMF661]

Hey guys,

Starting an investigation into a pretty decent oil leak. Have redone the upper/lower manifold gasket. The font of the motor (crank area) seams to be pretty clean. Seems to leave me with the oil pan gasket and the rear crank seal gasket being the culprit.
The oil pan gasket will require the removal of at least the two front I-beams. (Maybe I’ll do it when I install the 4-inch lift. The other requires the removal of the transmission (A4LD). Basically I think I am just complaining to you folks about it. But, any wisdom regarding decent dripping oil leaks off of the rear of the oil pan are more than welcome! :/

 

[adsm08]

Taking the I-beams out won't help. It's the cross member they hang from that is really in the way, and that is welded to the frame. Better to pull the engine out and do the oil pan and rear main seal together.

 

[racsan]

sure its not the valve covers? mine leaked some from there, drivers side, down the block and off the pan. wasnt a bad leak, just annoying. new gaskets helped but I really would of liked some cast alloy covers.

 

[rusty ol ranger]

I would degrease the motor then see where its for sure coming from.

Or just be like me and not really care lol

 

[Curious Hound]

If it’s the rear crank seal, you can pull the transmission and replace the seal with the engine in the truck.

 

[19Walt93]

The first several years of 4.0 leaked oil until Ford improved the intake manifold and valve cover gaskets. When cleaning the gasket surfaces wipe them down with brake cleaner before reassembling. I'd also recommend the Motorcraft silicone over most of the aftermarket stuff. I don't remember ever seeing a 4.0 with a rear main seal leak. I second the motion about cleaning the engine and actually locating the leak before you start tearing things apart.

 

[JMF661]

Thanks for the advice all. Yea, after taking a second look let’s hope that oil pan gasket is good :/. I did the valve covers and intake gaskets just the other day. I’ll have to do some cleaning on the underside of the motor and try to drill down on just where this oil is coming from. Normally I wouldn’t give a shit over an oil leak on a 26 year old truck, but I guess I’m just looking for trouble at this point.

 

[Shran]

Could be the oil filter adapter if it appears to be leaking from the passenger side. There are three o-rings there. Have seen them puke all over, rear mains too, but it's usually the lower intake and valve covers that drip down and make it look like other things are leaking.

 

[JMF661]

Could be the oil filter adapter if it appears to be leaking from the passenger side. There are three o-rings there. Have seen them puke all over, rear mains too, but it's usually the lower intake and valve covers that drip down and make it look like other things are leaking.

I am suspicious that this might be the culprit as I have found oil dripping off of the oil filter bottom. I will have to look into this.

 

[91 blue ranger]

Could be the oil filter adapter if it appears to be leaking from the passenger side.

That is where my 4.0 leaks.

 

[JMF661]

Mine is definitely leaking from there, I’m also certain it is leaking from the oil pan gasket. I’m in the middle of installing a lift and doing a rear axle swap. I plan on enjoying those for a while before I start tearing back into it over an oil leak.

I screwed up and put full synthetic oil in it right after I bought it, pretty sure that made it worse. Planning on switching to a little thicker syn or synthetic blend in a few weeks.

 

[91 blue ranger]

Yeah I want to fix the leak but I do not want to break the exhaust bolts. LOL And I am waiting to see how much it leaks.

 

[JMF661]

I am also not looking forward to messing with those old rusted up exhaust bolts unless I really really have to.
Pretty sure I’m going to endure the leaking for a while before I seriously consider fooling with it anymore.

 

[adsm08]

On the bright side the 4.0 was built in an era when serviceability still figured into the design phase. Have a few good round-off sockets on hand, run the engine for a bit before starting, and the bolts should come out of the heads easy enough.

 

[91 blue ranger]

Have a few good round-off sockets on hand

Sorry I do not understand this