My H3 has 180,000 miles and I just changed plugs this past weekend for the second time (First was 100K w/ AC Iridium).

To my surprise - and great concern - plugs 1-4 were extremely stiff / tight / hard to remove. Like, scary hard to remove. Like so scary, I'm not touching #5 and am afraid I never should have done any of them. The plugs didn't go into so smooth, either, but they went in straight and seated. I used anti-seize on the ones I replaced. I learned only after this difficulty that the H3 has an aluminum head. I'm getting too old for mistakes likes this.

Dare I ask - what did I do wrong/damage might I have done, how should I (gulp) attack #5, should I be so very happy that once over 200K it won't matter anyway as the head/lower end will probably be ready for replacement anyway? Oil consumption is more than it used to be between 5K changes.....

 

I moved this to a NEW thread, no reason to take on that old dinosaur thread it came from.

If you are removing #5, torquing it in the correct direction to back it out will not likely do significant damage, but anything is possible. The damage may have been done on the way in.

Yes all H3 motors are aluminum and spark plugs are not, that is why many people will use anti-seize on the spark plug threads to avoid galvanic corrosion.

I don't bother with that, but I make a point to correctly torque the spark plug going in. Most common cause of spark plug thread damage is people over-tightening when installing. For an H3/H3T that is 18N.m or 13lb ft. That is likely no more than 1/4 turn past finger tight gasket contact with the head.

 

Warm up the engine a little before you attempt #5. There is a sweet spot in temperature for removing spark plugs. I would recommend not getting the engine up to operating temperature. Trying it cold is also a mistake. Let it run for about 5 minutes from a cold start. If it's still tight i would leave it for a professional. If it comes out nice, do as the doc says. Use the correct torque specs.

 

You could spray some

Blaster PB PENETRATING Lubricant

AND LET IT SIT MAYBE RUN A HEAT CYCLE 5 MIN. RESPRAY

 

Thanks for all the comments guys.

I'm guessing I must not have applied any anti-seize 80K miles ago. I've never had to use a 1/2" socket wrench to muscle plugs the entire way out of their holes before; I usually wrench on old V8s where the plugs break free and then they all come out by hand (taper?)

I thought about heating up the head and can see how that should help - I'll try your sweet spot method below. I'll also spray liquid wrench into #5 a day ahead and run it etc, too as you say for good measure.

 

I can appreciate the old school approach with liquid wrench as I am not a spring chicken myself.
Liquid Wrench is old fashioned, inexpensive, outdated and just moderately effective as a penetrant.
Pick up a can/bottle of Blaster 16-PB or Kano Kroil they are much better penetrants.

 

My experience with Kroil is it is such a good penetrant that it will seep out of the seam in the can if you handle it too rough. It's good stuff!!