Okay it's time for a new thread, I'm starting to see things a little more clearly now. Today I made the mistake of turning off the radio on the way home (NEVER a good idea in a Land Rover!) and I'm definitely more concerned about my motor now.

It seems that under any load (even light acceleration in a parking lot, up a driveway hill, etc) starting at base revs, I can hear a distinct SINGLE cylinder tick AND knock per revolution. Passenger side - seems like it's roughly towards the rear of the engine / close to firewall.
I'm not entirely sure how this noise has been progressing (I know my paranoia is getting worse very fast) but I'm fairly sure the tick is getting worse over the past few months.

One distinct thing I've noted is that both noises seem to appear more obvious when the engine is under slight load. Even in neutral/park, if I step on the pedal QUICK but let off when it reaches 1300 rpm or so, then do it again to 1300, etc etc.. every time the engine begins to climb revs, the noises start - then the second I remove throttle input the noise falls off (even if revs haven't dropped all the way yet). This kinda hints at something cam/valve timing related? I know Jag has had a history of issues with this.

Another hint - when I replaced the plugs the other week, I believe #8 was the main one that stood out, as it had oil on it (threads, plug face, etc..) THAT plug would be the one located roughly in the vicinity of the noise I'm hearing - though I'm not sure what the connection between oil and tick/knock is.

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Background info:
2006 LR3 4.4 AJ-V8 w/ ~107,000 miles - full synthetic oil, routine changes, new spark plugs, haven't pulled compression (didn't have a large concern when I did plugs other week - I feel like an idiot now!)

Power and overall performance is good, if slightly less than I recall. I feel like this single-cylinder noise per RPM can sometimes be felt as vibration as well (maybe what I noticed in other thread).

One thing that did scare me when I did the seafoam induction the other day is that when I drove it afterwards "spirited" or however they want you to do it - I accelerated well till about 4krpm then power DROPPED off and rpms stayed the same and the valvetrain got VERY VERY loud when this happened - that's when the "engine reduced power" *bong bong* noise/warning and CEL illuminated.

FWIW the message never came back, and the CEL was gone by the next day. No idea what would cause that kinda valvetrain clattering noise unless "engine reduced performance" throws you into severe limp mode and a default SET cam timing which was not meant for 4krpm. I believe this to be the case because as long as the message was displayed, I couldn't accelerate beyond 3-4krpm in any gear.
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Some digging in prior service records (I have a friend, don't ask!) and found the following entry that actually scared me, everything else is pretty basic. On a side note, I got a new fuel pump at 61k miles, new rear wiper motor, steering intermediate shaft, etc.. good to know for future diagnostics lol.
I don't think it could be related BUT the exhaust manifold thing seems very odd? My passenger side DOES have what sounds like an exhaust tick/leak noise when I listen in passenger wheel well area, maybe the tech screwed up the head? maybe it's just whatever valvetrain noise I mentioned above too though. Driver side is nearly silent in comparison.

Weird thing is that from top of engine bay, there's a perfectly symmetrical and quiet injector/valvetrain tick and the motor sounds like it's brand new.

 

Man this story sounds a lot like what I've been going through with my Avalanche. Plug number one had oil on it, then a couple others followed shortly. Fixed under warranty was a bad valve I believe. It happened again, and supposedly was a defective valve (that they "should have" known about) also fixed under warranty. It all added up to 9000 dollars worth of work. Now, my warranty is out and guess what? Yep, oil on the plug again. Motor sounds fine, but I'm furious. Sure made me lose faith in Chevrolet with all the bs they keep telling me.

 

Wouldn't that be enough for lemon law, or close to it? That sucks man, I'd be super pissed!

Does anyone know about the valves Jag used with this engine? I've read a couple different places now that they're some strange design and actually adjustable?

Intake valve on #8 would certain seem to fit the bill (intake because VVT seems to make the tick respond to aggressive load / throttle changes, almost gone if no load).

Ugh what if the tick is just a manifold leak though? That usually only happens under load too - that would just leave me with the "knock" part of the equation.

 

I believe I've read some other posts on here about a tick that the owner attributed to exhaust manifold bolts that need to be torqued down a bit tighter. You may want to do a search and see what you can find. I have a compression gauge you're welcome to borrow if you decide you want to run the numbers.

 

Yeah I've put it off for a while since I didn't think there was any damage that it could really cause (and it's apparently a real PITA to access) but now I really should do it to help rule stuff out.

Thanks, I've got one at the shop actually. Was 20' away from me when I did the plugs the other night.

 

A cheap mechanics stethoscope is great for listening in on engine noises.


Took ours in to the dealer for a 90,000 service a couple months ago.
Told them to drain trans and change filter. He warned me that doing that requires removing exhaust manifold and most likely will snap bolts.


Told him to do trans flush for now instead.

 

Interesting.. ok so I guess that was to be expected. I wonder if that was the driver-side and that's why only passenger side appears to have manifold leak?

I have a 6 channel chassis ears diag tool I can use - just clip a lead to each corner of the motor and maybe one on each exhaust manifold bolt. Drive around with the headphones on and switch channels to compare sides. I bought it specifically for the LR3 driveline since there's so many bizarre noises coming from so many different places.

 

I remember starting a thread in D2 years ago about fixing a tick. I put a new radio in With that said, I know how it is to have one of these start to age and you play "name that sound".
The fact is, most of these have a slight tick/tap. No more than anything else with 100k on it though. A quick video with the sound would help.
If there is oil on the one, are you sure the valve cover isn't seeping in that spot? I figure it's minor, so she doesn't smoke or cause a misfire. These motors seem rather robust for the valves, especially with proper fuel and oil as yours sounds like it gets.
Only other thing I can think is the seafoam loosened up something that got sucked in, but being it is the back cylinder I'm not sure about that. When my pcv went all that oil caused misfires in the front of the engine.
Throw a double shot of Lucas in the tank and see if it quiets down a bit. My engine isn't loud, but is a touch quieter when I throw that in every so often.

 

Seen this seneral times, usually the rear RH side, even seen it where the bolt had backed all the way out and was missing.

The valves in this are standard, and not adjustable. The lifters are solid 'selectable bucket' design, kind of like shims, but the lifter itself has different sizes.

I would check for exhaust manifold/gasket issues before going any deeper for the noise, and just FYI, the passenger's side is bank 1, so cylinder 7 was oil fouled. The rear cylinders tend to get more oil fouling than the front on this engine, due to intake manifold/PCV system design.

With the MIL turning on and loss of power being directly after the seafoam, don't be concerned about it, that was most likely just a ton of immediate misfires due to it sucking all that extra fuel/dissolved oil into the cylinders. Might be a good time to take a look at your PCV valve too if you had any standing oil in the intake, but not causing this issue at all.

 

Unfortunately, it seems like this is getting worse. I almost feel like the more I "clean up" all the other random things that slightly detune an engine (plugs, TB on ours, etc) the tick, knock, etc is getting worse.

The worst harmonic vibration from whatever is the root cause, is just a little over 1250rpm in park/neutral.

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Just thinking out loud diagnostically.. but most fuel and ignition errors would be throwing a code, there are none.

Can a mechanically-caused miss (valve problem, rings, whatever) cause a fairly harsh harmonic-type vibration in the cabin? Maybe someone with knowledge of how the 4.4 is balanced and how sensitive the vehicle is to harmonics can elaborate.

If not, then I feel like the flywheel or some other initial part of the transmission is the only thing with enough mass and diameter to cause the park/neutral vibration - as nothing else in driveline is turning yet.

Unless of course it's in the bottom end of the motor; but *knocks on wood* I just really feel like that's unusual for these motors.

Then again this problem seems to be unusual for these motors anyways.

Next step is compression test - if that shows something weird, then valve covers - but that's probably as far as I'll want to go. Trans = $$$$$$ and bottom end or even heads = $$$$$$ but I wouldn't mind messing w/ valves or something I guess.