Common oil leak locations on a 4.0 OHV?

[RangerX]

I have an oil leak that’s getting on the drivers side exhaust manifold, enough that it kind of scares me to drive. As soon as the engine gets hot, I get smoke oozing out of the hood gaps.
I can’t see clearly enough to know where or what the cause is.
Engine has 350,000+ on it, never been worked on except for a lower intake gasket 7 years ago. I’m thinking maybe the intake manifold bolts loosened up?
Or valve cover gasket? Head gasket?? Not sure what else there is with oil, that’s above the exhaust manifold...
There’s no coolant in my oil, and no oil in my coolant. This engine has been leaking various fluids from various spots for years and years, but this is new.
Thoughts?

 

[corkey]

valve cover gaskets harden and get very brittle over time,, than leak in weird spots,, i'd say let the engine cool than look at them and see if yiou can find a trail leading away from that one to the manifold,
it should be fairly visible , mine was,, same side, by the middle exhaust ,,

 

[corkey]

the back corners can be bad too

 

[Stic-o]

New motor? I think you know your on borrowed time, and probably have been for a while. I know that's not what you want to hear...

Buy my temporary '97 explorer (make a good deal) I've been driving and we'll find you another good block to ship it there. I'll throw it in the back with what ever else you want from state side. Although it probably better to just find a motor there.

 

[410Fortune]

above the manifold on drivers side will likely be the valve cover
Doesn't hurt to have a look at the oil pressure sender and make sure its not squirting out

On the pass side you have the valve cover gasket and the oil filter adapter that are common oil leaks on the OHV

Try to get 500K from that bad boy!

 

[RangerX]

Right, Jamie?! I just saw that thread yesterday where someone had 658,000 or something on his! We’re all on borrowed time, Steve, vehicles and otherwise!
Steve, I have a parts truck with just 96,000 miles on it, so I do have that option...
But I’ll check the valve cover.

 

[RangerX]

Jamie, would a valve cover leak cause a high idle? I have that too, 1100 rpm. I’m think8ng not but might be worth asking.

 

[410Fortune]

High idle OHV 4.0 is usually #1 intake leaks after the MAS = un metered air and the computer is trying to compensate
#1 suspect is plenum to intake O rings, gasket, followed by vacuum lines and then lower intake gasket leaky
I have had the valve covers off plenty of OHV with them running at warm/low idle ....looking for that lifter tick.........
so Im gonna vote no


Look for buildup of soot around base of upper plenum. See anywhere that dirt may be getting sucked in?
OHV or SOHC with any sort of high idle over the stock 650-800 when warm, first thing I do is re seat intake plenum(s) and usually, just because I can, I re seat injectors w new O rings and bench test all 6 of them.
Have a good look at IAC and IAC gasket, also replace the EGR O ring if you have plastic intake
I have fixed a low idle on OHV by drilling small hole in Throttle body plate and I have fixed a high idle on OHV by using a mustang adjustable IAC bypass spacer dealio....idle on OHV can be a finicky thing especially when we get older and have lots of non OEM parts like MAS, IAC, intakes, exhaust, etc.......using auto computers with 5 speed transmissions, you know the kind of stuff ranger and explorer guys are always dragging over to my house

If you have a high idle that you can't sort out, you have cleaned the IAC, new intake gaskets, fixed vacuum leaks, reset the TB throttle stop screw, etc etc consider this
The older OHV trucks I have started to see more and more bad PCM's as they age and are exposed to the weather, leaky cab, moisture, etc
When the PCM goes wonky it can do some funky things, high idle, 02 codes that cant be sorted, different codes during different KOER tests, not consistent
Usually you will have a CEL with some strange codes IF the high idle is being forced by the faulty PCM.
Reman PCM from Ebay if I dont have the correct one in my collection is a good way to go
They also smell of burt electrical wires, the real simple PCM sniffer test LOL

 

[RangerX]

I finally went and took a real good look at the suspected leak area, here’s what I see. First pic shows location, second pic shows that it’s probably that back corner of the valve cover, yes?

 

[Jessica Pruett]

Yeah that's where it's coming from. Gaskets are easy to change.

 

[410Fortune]

Yes valve cover gaskets\
If you are ambitious this is a good time to re seal the whole top of the engine, the lower intake gasket probably needs to be changed also...with age and miles they start to develop little leaks

 

[RangerX]

Ok thanks!
LIM gasket was changed 50-60K ago.
Anything I should to the valves while covers are off?

 

[gmanpaint]

Does it have the infamous lifter tick? Be a good time to change the rocker assembly and push rods if so. Delta cams makes a kit for around $200, last I looked.

 

[Turdle]

don't forget a new pcv valve even if the old one seems good.Good PCV will help to vent the pressures which cause gaskets to blow outward in the first place.

 

[RangerX]

Thanks for those.

New PVC is a good call, it may be the original in there!

I’ll look into rocker assembly and pushrods, but it may be over my skill level.

 

[RangerX]

Hmm, looking at my engine to see what needs to be removed, it seems like a lot needs to be removed. Does the entire intake need to come off, or just the upper?

Also, @410Fortune when you say first thing you do for a high idle is reseal intake plenum, what exactly do you mean?

 

[410Fortune]

I mean there are O rings where the plastic intake meets the metal intake and fuel rail. Those O rings go flat and dry up causing intake leaks, ethenol fuel seems to make things worse.
I use only Felpro gaskets (victor reinz is good too for the 4.0)
removing the upper plenum on a OHV 4.0 takes me about 15 minutes and the intake O rings and EGR O ring are about $20 so its a quick and cheap fix
To do valve covers on a OHV you are going to have to remove a few things, I believe the alternator and upper intake along with some plumbing...not a terrible job at all
OHV 4.0 is the easiest of the three engines to do top end gaskets if that helps motivate you! LOL

 

[RangerX]

It took a while, but I finally just got the gaskets done. Valve cover gaskets along with upper intake gasket.
I think he found the cause of the high idle. There is a leak in the brake booster, and fluid leaking between it and the master cyl. When the booster hose is disconnected and covered, the idle drops down to a normal level. So, replacing both in the next couple days and I should be driving again.