Plugs from cylinders 1 (bottom right), 7 (bottom left), and 8 (top left) look like they have oil all over them, but appear to have most of the oil from what I would guess is just a valve cover leak. Plug 8 appears to be the only one that may have some oil fouling of the electrode (though it's hard to tell from the pic) and would be the one I might be concerned about. Of course, that's the hardest one to get to, but might want to consider checking compression if you have a gauge and the time... :P

 

I have valve seat loose in the head causing misfire and rough running .

 

Great - that sounds more along the lines of what I was expecting. How did you confirm and what cylinder do you think it is? I have a distinctive tick and it seems to be relative to a single rpm (not 8/16 per rev for example).

I also have a lower frequency "knock" that's clearly heard in the cabin at idle... that one is what really worries me.

Either way as my OP states - I fear mechanical.


UPDATE ON LIST:
I finished spark plugs, finished all in about 45 min first time so I'm happy with that. LR did a good job (for once) of making a maintenance job easy. Compared to ford 5.4 or V10s this was a cake walk!!! See above images on end of first page for pics.

Cleared codes from sea foam debacle, did plugs, cleaned TB, MAF, replaced coil capacitor w/ updated LR P/N, replaced dipstick o-ring.

Drove easy this time for 10 min, till I got stuck behind an idiot going 35 in a 55... made it to a passing zone and flipped it into sport mode and floored it... she took off really well, and obviously had my regular engine performance back. I'm guessing the "reduced engine performance" automatically enables a rather severe limp mode.

Oddly enough I did have a CEL pop back up around the same time (I think it was a minute before I passed the car actually) so I'll pull the codes and update everyone in the AM when I'm back at the shop.

Idle seems smooth but the vehicle was warm so it's hard to tell.

I think I'm a little discouraged by the whole thing due to discovering the LOWER tstat housing leak (after having bought upper) and while I drove it after sea foam I discovered a fairly loud "scratch-scratch-scratch"-type wheel noise from the rear (I think? It was really hard to tell) which sounded like a wheel bearing failure.

Definitely looking at a lot of blood sweat and tears (and $$$) going into spring.

The only consolation is that most owners would probably be totally unaware of ANY issue I just mentioned, so I think I'm just being a little over cautious, but I really like keeping my vehicles in showroom condition/performance - it's not really an option if it's a tow rig either; I need that performance and safety/reliability every time, especially when I tow the horses.

 

I know it's not exactly easy to put a noise into words, but a "scratch-scratch-scratch" sounds more like a brake pad rubbing to me. A failed wheel bearing is more like a rumble. At least it was a rumble for me in my Audi when it failed... Does the noise go away when you lightly press the brake pedal?

 

Nah, I tried that - exactly the same on or off the brakes. Wish we had a decent 4 post lift so I could spin the wheels and listen. I do have a 4 channel chassis ears system but it's a b1tch to set up lol. My rear brakes only have about 5-10k left on them before I trip the sensor most likely - but I can't make a connection between that and the noise I heard. Maybe something with the EPB?

 

Oh another update.

Started and idled well this morning cold @ 30 deg, still a slight vibration in the same RPM band as before, but I'd say it's about 50% better. When you hold a raised RPM and let off the gas, it doesn't drop below 500 / almost stall anymore - just smoothly approaches idle.

Seems more snappy - quicker on up-shifts, which makes sense if it was having a hard time pulling up revs.

CEL that came on w/ drive home is the same P0175 and P0172 rich both banks. Cleared it again - still thinking that's related to seafoam (never seen it before yesterday) although there's plenty of threads about the codes on forums so...

 

Interesting and promising. I'd love to do the plugs myself now, but the thought of tackling the job outside in winter temps has me thinking I might wait until spring or have my mechanic do it.

Did you have any issues with sticking coil boots?

I agree with cmb6, usually a wheel bearing is a roar or a rumble, though it may just be the early stages. I'd just keep an eye on it, as it very well could be the brakes.

 

EstorilM,

Two quick notes, the SeaFoam always causes a rich CEL for me but I have used it to clean the engine successfully and the codes stop after 1 or 2 clears for me.

Second, I've got a rear hub assembly if it turns out you need it. It's just sitting in a box waiting for a use.

Cheers,

Ian

 

Yup second code clear and it's gone

So I should mention that I also dumped a can of Liqui Moly Jectron and Valve Clean on a 1/4 tank Wed. For those who aren't familiar with the company, they're amazing.. pretty sure branding and product claims in Germany are practically legally-binding, and everything they make is the real deal, ESPECIALLY their Group IV synthetic oils. At like $11+ /qt I haven't tried it yet in the LR, but on my high mileage M3 it totally silenced lifter noise and LOUD VANOS chain noise when I switched from M1 15w50 to Lubro Moly 10w40. Yeah - lighter oil but infinitely better friction control.

Last night I hit empty and put regular premium in, and now (with clean gas, and presumably slightly more clean injection/valvetrain system) my MPG is about 5-6% better (little over 1mpg from what I've seen so far).

I also forgot to mention that before all this, my power band was crap - I'd hit a zone around 4k where it would just JUMP and all of a sudden develop more power. I wonder if the VVT solenoids were clogged or something? I only have about 2k miles on new oil, hm. The power band is MUCH smoother now. That could have also been the ignition or ign. interference/capacitor problem too as that likes to happen in higher revs. My LR3 did have the old capacitor design still (new unit is super cheap at dealer for once.. like $18).



Cold start this morning was great, 19 degrees and even quieter idle. I will say that the Liqui Moly cleaners definitely seemed to have quieted the injectors somehow too, ticking is almost silent - I also saw many people mention this on amazon (I get it through NAPA but amazon's a good place to randomly see reviews lol).

My low frequency "knocking" noise from either front wheel well didn't seem as pronounced when I got home after an hour commute from hell, but that could be due to a number of things. I wish there was more of a knowledge-base out there for the internals of these 4.4s. I sometimes look at the jag 4.2 forums for hints, but it's mostly a suspect VVT system that comes up. LR had issues with that as well, but *knock on wood* I don't have the cold-startup valvetrain noise TSB. I think that was a low-mileage early problem on these?

I just see hardly any mention of a lower-end catastrophic failure mode in these (again, *knocks on wood*)



Maybe I'm developing some target-fixation here though. What about the trans?
I came across instances of the ZF6HP in BMWs developing a similar noise in park/neutral when the torque converter ages and the rivets wear on the forward drive plate? I'll need to do some more research into this. I do know for a fact that the TC in these rovers tends to act much differently now than it did when new, as these heavy vehicles put more age on the TC.
That's generally the same "low" location / area that I hear the noise from. Depending on whats happening it has the potential to cause a balance problem as well. The location would actually make the noise and the vibration a little more obvious (both outside for noise, and inside for shake).

I guess I can drop pan and do fluid first, check filters blah blah. If they're wearing/worn I should be able to see some flake in fluid. I really don't want to buy that liquid gold though.

 

EstorilM, where did you get the O rings for the dipstick? I get oil building up just below the o ring but no leaks so far. I don't like that oil travels that far up the dipstick but this could be normal?

what socket did you use for the plugs?