At 90k and just did the valves and doing plugs now since I'm in there (engine completely cold). The old ones were a little rusted/gunked up around the threads, typical wear nothing abnormal. But whatever is on the threads in the head is making the new ones turn less than smoothly and that tension is enough to trip the torque wrench up on such a low value. In fact i've hit the click a few times only to discover that another 1/4 turn will break it free and keep going another few turns. I've tried hand tightening and backing all the way out to chase the threads and it seems to help some. I kicked it up from 15lbs to 17.5 (Ive seen speculation that it can be up to 20 but that makes me a little nervous being aluminum). But no matter what it seems like it still wants to go further after it hits that click. Really doubt my wrench is defective. And I don't particularly want to spray anything down the hole or try to ream it. Seems like a bit of anti seize would help, but laying off on that per mfg recommendation.

This has me real paranoid now given the issue with them backing out with vibrations. I'm not confident I've got them torqued properly. Heres an example of one. This thing clicked numerous times, but you can see from the last 4 threads it wasn't even close to seating. Anyone ever encounter this or have thoughts/advice?

 

You could chase the threads with some fuel soluble grease. o-ring grease perhaps? i've knotched bolts and even an old plug with an angle grinder. if you go a less embarrassing route, just dont exceed plug depth. or crack your head.

 

Thats actually a pretty good idea. I can get my dremel and just notch one of the old ones. Didn't think about that.

I swear that plug in the picture is #4 and I've backed it in and out a dozen times brushing and wiping off in between every time. It's turning a little better now, but it's just as dirty the last time as it was the first time. It starts to squeal when I get midway. I've never run across this issue in any engine big or small that I've ever worked on.

 

The Dremel is a good idea, I never thought to use one for that! the angle grinder freaks me out and can be sloppy. Thank you!

I hate to encourage paranoia, but the seizure of the plug reminds me of my experience with a cracked head.. And I would have to encourage checking around the plug hole with a bright flashlight/headlamp for a hairline crack.. If there's none though, a good cleaning may well do the job.
This may be an odd suggestion, but if you have the plug removed, perhaps you could rub a pencil along the rim of the plug hole 🥁 If it cracked, you should then be able to feel and potentially see it. The funny thing about cracks in cast aluminum (i can only speak to my singular experience) is that they can stay very well hidden.

So if chasing it doesn't work, that's what I'd suspect. Even so, if the car runs fine with a cracked head, then i'd take note of it and deal when i next had time and funds.

 

I've chased it and hand tightened with a regular 3/8 and it's def in their snug now. The torque wrench still wants to go a little more but I feel more confident now that it's proper torque and the extra give is just the byproduct of having a big long wrench on it. Interestingly enough I probably screwed myself by chasing these threads. That crud was probably doing a good job of holding the plugs in place from backing out. Now that they're clean I'll prob have to recheck during the next oil change.

Interesting point about the crack. Did you experience excessive blowby when you had that? #4 exhaust was the only valve that was decently close to spec. But I could swear that there seemed to be a little more crud in the threads and on the coil boot than the others. I actually have a compression gauge so I may just try that. I'm not particularly paranoid about it. But I am a little curious now.

 

Torque wrench output can vary based on speed of rotation! I've got an old dial type made by CDI (snap on subsidiary, whatever that means) that doesn't ratchet and shows visually as you progress to desired torque. I like seeing the magic happen but it's so darned clunky and delicate that putting the socket on shows a reading of up to 10lbs if you're not slow n smooth.

I think excess crud could encourage blow-by. You know, inconsistent sealing. Get it down to 20 and call it good. Maybe check back in a month or three? I've actually found that when one of my plugs loosened, so did the small bolt holding their coil/wire in place. makes sense, ey? So I feel em over whenever I pop the hood.

The pic shown wasn't of the head I worked on, it's from a 2.0l turbo vw engine I believe. My cracking was the result of ejection and thenn When I rethreaded a hole I sent the new sleeve in too deep. Never again. timing chain coincidentally snapped due to deterioration of plastic on its guide, likely the result of overheating by the previous owner. Piston impacted the sleeve and stuff ran afoul!
I'd have to dig deep to find my old pics and transfer em from my old phone. But the cracks shown here are inside the cylinder, and not visible from the outside (not unlike what i discovered with my issue). Yet they can still go into the plug threads part way! Cast aluminum is riddled with inconsistencies as I understand it (so said the machinist that welded cast aluminum for me, the guy was the real deal. Its a rare talent)
Mine separated half way.. the bottom half of the plug hole separated a smidge.
Oh man! a compression gauge might be worth something, I didnt think of that!

 

Glad to see things worked out fine with the seizing plug.
How difficult is it to do the valve clearance on the MkII head, seen people using bent feeler gauges to take clearance readings?

 

Threadjacker!
bent feeler (tappet) gauges or straight ones that'cha put some curve on. its no big deal. do need a crows foot to torque the nuts on the valves. I just purchased some new tappet gauges via amazon that i'm looking forward to using:
They have sizes right in the middle of the gap range. and it comes with two handles (not actually filthy like shown in the image) allowing me to lazily set two up, one for intake, one for exhaust, and just grab em without looking up the clearances again.
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Oh man. If I ever had to adjust the valves again, I would happily pay for that gauge set. Those handles look nice. I had to ruin a perfectly good set of flat gauges by bending them just to do this job. No one in town had offset ones in stock.