2000 V70XC - Should plugs be changed hot or cold (or warm)?

[v70XCSteve]

I just bought this 2000 V70-XC and I'm planning to do a "tune up" and I'm wondering if it's best to change the plugs hot or cold (or warm)? 175,000 miles. Not sure if they've ever been changed, or when it was done last, which worries me since I don't know if they were anti-seized or if I'm in for a fight. What, for this car, would insure my best chances of success in getting these plugs out safely (besides being gentle, by hand)?

Any other tips that come in handy? Do I HAVE to disconnect the turbo line or can I persuade it out of the way, enough, if I only unscrew the point where it is secured to the block in the middle? These hoses look old and I'm not looking for a bigger job, right now, than plugs. Can I get the plug job done without removing the turbo hose?

Also, one of the torx screws that holds the spark plug cover on, just spins (with moderate resistance, not free-spinning) and doesn't come out. I tried encouraging it out with a flat screwdriver underneath as I turned it, and I tried turning while pulling upwards with needlenose pliers, but no-go. It doesn't want to come out, but it'll turn. I'm thinking about holding it with needlenose while I either drill-off the head and forget about it thereafter, or drill a pilot and try an easy-out reverse thread bit (never did that before). I could always just dremmel around the screw to cut the plastic cover and forget about that screw (leave the screw alone). Any thoughts or ideas???

[JDS60R]

Plugs - cold
Turbo tube - off
Spinning torx 30 is an issue. If it will not unscrew out you may have to drill it. I do mot know why it is free spinning unless its badly stripped. Its ok to lightly pry it but the plug cover is plastic and will not take much to break.

[abscate]

I would just cut around the plastic ...you can always get a junkyard plastic cover.

If you can't get it with a vice grip pulling up an EZ out isn't going to help, though.

[RussB]

I always Remove the plugs with the engine warm when dealing with aluminum heads. Squirt a little Kroil or PB'laster down each plug hole before trying to remove them. A little penetrating oil can really help

[mecheng]

The block MUST be stone cold when installing the plugs; especially on aluminum block. Use a bit of anti-seize on the threads.

[erikv11]

Interesting; I've never, ever thought about this, just pulled and reinstalled the plugs. More than a couple dozen times. Which means the engine was often hot or warm, because I just pulled it into the garage. For example, to do a compression test you need a warm block, and you need to pull the plugs, so ...

Obviously you guys are thinking about expanding metal for some reason; why "MUST" the block be cold?

[regent]

... why "MUST" the block be cold?

I guess - for convenience and safety - working on a hot engine may be quite a challenge and produce unwanted sound effects emanating from your mouth (please don't ask me how I know)
I've never waited until stone cold to do plugs - just enough to be able to keep my hand on metal for about 10 seconds without screaming 'ouch'

The most important precaution is to ensure the engine is OFF and the key is OUT before removing the coils/plugs (high voltage is no friend to anybody)

Now, if this is seriously about thermal expansion, then no worries either:
The aluminum alloys (00V70 head) expand more than steel (plug shells) do, and here is why:

In theory, the heat expansion coefficients of Aluminium alloys vary in the range of 12 microinch per F, and those of steels are around 6 (or only half). In simple realistic terms, the plugs should be 'tighter' to break loose if the car is 'frozen' at 40F, as compared to a warm engine about 140F

Now, if you are dealing with a cyl. head material other than Aluminium alloy, then the above can change either way.

[jblackburn]

About anti-seize on spark plug threads:

http://www.ngksparkplugs.com/pdf/dyk_5points.pdf

*Alters the tightening torque by up to 20% which may cause over-tightening (or breaking the spark bolt)

*Isolates more heat into the spark plug therefore causing the plug to increase the heat range above specification (can cause detonation/pre-ignition).

[JDS60R]

Oh no - not another "when to change spark plugs hot vs cold" and a "should you use anti seize" discussion. Here is the little info I have . I am going to drop it here and get out just in case someone wanted to know what I think.

Aluminum and its alloys significantly lose strength above 100C (212 F). Those little threads need all the help you can give them. So changing them cold seems to be a good idea.

Also dissimilar metals put together with a catalyst (heat etc) tend to galvanicly (spelling?) corrode

In previous discussions about anti seize, it is suggested that an anti seize compound that gives good electrical conductivity "once dried" also helps exchange heat well. I find a good copper anti seize ( loctite comes to mind) work much differently than my nickel (permatex ) antiseize when it comes to electrical conductivity. (They idle differently in my opinion -maybe I'm nuts but that's what I have observed)

I use loctite copper on my spark plugs . I use the nickel for turbo mountings etc. (copper works fine here too but I have this big can of nickel and temp rating is supposed to be higher)

I have done testing on the torque statement of an increase of 20 % with AS but 20 % of 14 or 19 ft/lbs is only 2.8 to 3.8 ft lbs more. Tightening a 14mm spark plug 14ft/lb and then again at 16.8 ft/lb yields almost no movement (try it yourself - or do it with and without AS - you will see the difference). Sprak plug manufactures normally give you a range with more than 20% variance allowed(14-19 ft/lbs). I do not know anyone who has first hand experience of the "spark plug is moved 3mm's deeper into the head " issue some statements proclaim."

Some of the best responses come from the anti-seize companies who explain how antiseize works and can give you tests to back it up. It makes me want to own and use quality anti seize .

That being said I have seen first hand damage to heads from spark plugs being allowed to gall in. Also I have to put out there that the alloy Volvo uses very rarely shows you trouble. I did have a line of heads off of 4 cylinder Corsica's. I think that alloy must have had issues as those were the worst I've seen.

[RussB]

The block MUST be stone cold when installing the plugs; especially on aluminum block. Use a bit of anti-seize on the threads.

No, it doesn't NEED to be cold, you silly goose! I Luv Anti-Seize