So to recap my recent problems with my 4.6:

Noticed an occasional 6th cylinder misfire code, very random, and not often.

Figured I'd get new plugs as part of my new ownership maintenance. Also noticed I was using up oil at a higher than what seemed normal rate - I check it all the time, just a habit.

Fast forward to this weekend, I popped off the engine cover and noticed liquid oil pools right around the valve cover/coils/boots/injector area. Like little pools of liquid oil - not just fuzzy sprayed oil on surfaces. I also noticed the 6th cylinder spark plug hole has been repaired, with some sort of extension, that put the plug electrode about 1" above where it should be - I a fixed that with a helicoil, and snugged down the plug and thought all was good in terms of the misfire...

Friday after this repair I left from Boston to Montreal - made it up there fine - checked oil, and coolant, all seemed fairly unchanged. Today when we went to leave, I immediately get two codes from my OBD bluetooth adapter - I checked because I felt the bogging - 5th and 6th cylinder misfire. Stopped and pulled off the coils, wiped the oil from them and went on my way. 5th cylinder code disappeared - 6th still there...going to replace all plugs and coils, so we'll see what that does to the misfire code. now onto the confusing part:

I noticed when I dropped my buddies off, a good puff of blue smoke after accelerating from a stop - and its running even worse (only code still 6th cylinder). I check the dipstick, it's down to about the last millimeter of the cross hatched area ( I topped it up to about 7/8 coverage on the hatched area before leaving this morning).

Would a leaking valve cover AND leaky intake manifold cause any of the leaked oil to drop into the intake and burn up upon accelerating from a stop? Didn't notice any blue smoke while driving, just acceleration from a stop. What else would be the oil consumption? I already bought a filter housing gasket, changing that tomorrow but I'm concerned with the liquid oil on top of the engine.

I'm thinking since the PO repaird the plug hole in cylinder 6, a bigger hole was tapped which was for that ****ty adapter, that wasn't meant for this engine....then I re-tapped the threads for the helicoil insert - which could have had less than ideal material to cut for proper tapping. Could this allow the leaking oil from the valve cover - it's significant - to drip into cylinder #6 combustion chamber and create the little bit of smoke? I'm going to replace the valve cover gaskets and the intake manifold anyways - we'll see if the blue smoke is still there after that.

I'm going to see what prices are for a used head (I can install that myself, after machine work of course), and compare it to a time-sert BIG kit to determine if I need to revisit the spark plug hole/threads for cylinder 6

If it turns out to be the rings - I'm kind of at a loss there - I've swapped engines, heads, cams, gears, timing components in my 25 year old BMW...but never touched anything on the lower end aside from oil pan removal, so here's hoping

 

Are you sure what you saw was blue smoke from burning oil versus gray smoke from running really rich (due to the misfire on cylinder #6)? You might want to attempt to catch a sniff of the exhaust next time to see if it is definitely oil or if maybe it's unburned fuel.

-Rod

 

never thought of that...the guy I bought it from did say "he had to replace one of the spark plugs every 4-5 months" because it kept getting oil on it. He said his mechanic said it was the rings - but after a quick look, it looks like the oil on it was from the leaking valve cover.

He said after he changed the plug it ran fine - on cylinder #6 the plug was fine when I took it out, so I'm thinking when he changed it, he cleaned the coil/boot from the oil and that's what made it run better, not that the actual plug was changed.

I'm digging into this weekend after easter - new valve cover gaskets, intake manifold, thermostat, and I'll do some compression tests to rule out the rings.

I did'nt catch a whiff of the exhaust, oil would smell almost like a diesel engine right?

 

Thread moved to the Modular V8 forum per OP request.

 

I think you're probably exactly right that the issue is really the leaking valve cover gaskets/spark plug well seals saturating the coil to plug interface and causing the misfire rather than oil coating the combustion chamber side of the spark plug. Leaks in the spark plug wells was pretty common on this type of head design. I suspect changing these seals will take care of your issue.

Oil burning in the exhaust would smell like, well, burning oil, or burning rubber (think tire smoking). Rich exhaust also has a characteristic odor, but it's not so much of burning oil or even unburned gasoline. It's more of a sooty smell I suppose. Kind of tough to verbally describe. The coloration of the rich exhaust will be more of a gray or charcoal color, not much of a blue tint like oil.

-Rod

 

welp....bad news. Cylinder 6, compression...20psi. I hooked up the compressor to the head, and could feel slight air coming out the exhaust - must be an exhaust valve @ cylinder 6.

new question - what's the typical cost for a head job? Assuming it's only one bent valve, do I need to replace all valves on that side? What's needed - deck/cut, valve seats, should I replace all the rocker arms/springs?

 

Bump

so I was reading another post regarding open valves - it appears it can be a couple of things - bent valve (removal of head), burnt valve (removal of head), bad lifter, or bad spring....I bought a borescope on amazon, I'm gonna take a look tonight, hopefully if everything looks ok, I'll just change the spring and rocker arm and give it a shot. Anything to avoid taking the head off at this point is worth a shot.

There isn't any metal on metal sound when running, so I'm wondering if the valve is stuck open, when the piston raises and hits it, maybe it just pushes it back closed as opposed to bending it? Can that happen?

In the event I need to change the engine (rings are ####ed, or there is cylinder wall damage) can I use any 4.6 from the 3rd generations? Are they different when they went to drive by wire? What about the 3v from the 4th gens? I obviously have all the accessories from my 02 that I can swap onto it, just want to expand my possibilities for pricing reasons

 

I bought a new lifter/lash adjuster at O'Reilly last night and a rocker arm. I can't see anything wrong with the spring. I took the lifter out and put the new on in along with the new rocker. I took the front cam cap off and there is some scoring along the cam and the cap - is this junk?? (pictures below) How does a bad lash adjuster behave? I put the one I took out into my vice and compressed it - oil came out and it didn't seem to be binding on anything. I took another one out just to check, and it compressed in the vice, but there was barely any oil that came out, and it again didn't seem to be binding

I also noticed there appears to be no oil restrictor as I've seen in some many other 4.6 engine posts/threads/youtube videos...any idea what's going on here: ( I know there is a rocker arm off...I did that)

 

So I probably need a new engine for my 2002 4.6....when I go to car-part.com it shows that 2002 4.6's are different than 03-05. I called up a junkyard and told them I was looking for an 02 4.6 - 8th Vin Digit "W" and he said he had only 1; I asked if he had any other 03-05 explorer/mountaineer 4.6's and he said he had 2 explorer & 1 mountaineer, but they wouldn't work in my car because whatever he was using to look it up is different (assuming car-part.com or something similar)

Can someone confirm this isn't the case? They are all interchangeable correct - the 3rd gens?

I have all the accessories from my current 4.6 (2002) - intake/throttle body/etc...so I don't see how even the drive by wire 4.6's wouldnt work, correct?