View Full Version : removing stuck spark plugs?

12-16-2012, 09:57 PM
I was trying to do a little work on Bec's Sequoia this morning but got stymied but stuck spark plugs. I didn't want to crank on them too hard for fear of breaking them off. Can I spray some Liquid Wrench down and let it penetrate? What else can I do to break them loose?

On new plugs, I've always added some anti seize but I was just reading some stuff about not putting it on the denso/ngk iridiums. Is that really an issue?

12-17-2012, 08:05 AM
You might try running the engine for a bit to warm it up first, then try again.

12-17-2012, 10:47 AM
Ttub is right, get the engine good and warm to expand the aluminum in the heads. The Linear Temperature Expansion Coefficient of aluminum 22.2 (10-6 m/m K) and steel is 13.0. That means as your cylinder head gets up to temperature, the head will expand 70% more than the spark plugs and it will loosen accordingly.

Be sure to use antisieze on the new ones. There's also the potential for bimetallic bonding, which is where two dissimilar metals will fuse. This can cause galling in the threads on the head when the offending spark plug is eventually removed. Unless your Sequoia has been experiencing heat issues or the spark plug insulation has been compromised, it's not terribly likely, but an ounce of PM is worth a whole lot of swearing down the road.

12-17-2012, 12:34 PM
A little Liquid Wrench would be fine to help get the old ones out.

I receive Motor magazine and they rail repeatedly against using anti seize on spark plugs, and showed an example photo of huge globs of it shorting the electrode. Obviously, a little dab will do ya' - so use some, but be sensible - put it on the threads, not in the block and wipe off the excess. Motor mag also implied that it could prevent proper plug grounding in some circumstances, but I cannot comment on that - except that I haven't seen it to be an issue.

12-17-2012, 01:27 PM
If you do use anti-seize on your spark plugs you must be careful not to over torque. It's very easy to strip threads or break plug shells. Most specs say hand tighten until the crush washer touches and turn another 1/2 turn, follow this exactly. Or reduce your torque wrench setting by about 50% (which is really important anytime you use anti-seize, not just on plugs).

One thing to note is that you must use anti-seize on uncoated spark plugs. These are usually the dull or darker shells and guaranteed will corrode with all the magnesium chloride around here, especially with aluminum heads.

Newer plugs and more expensive plugs are shiny due to their nickel or zinc plating, which is to prevent corrosion. That is because they are the one designed to be left installed for 100,000 miles as opposed to the cheap ones (like my 22R-E uses) which you replace regularly. You should not in theory need to anti-seize them, but I've got no experience with anything that uses them (we did not own the 4Runner long enough to do more than oil changes and everything else has been old junk).

They make anti-seize with copper instead of graphite or nickel in suspension just for things that need to be kept from galling but still conduct, like spark plugs and senders. In any case, be sparing with the stuff, just enough to get the job done. That is what I put on my spark plugs. If it causes a reduction in spark energy I can't tell, my truck is slow regardless. I don't fail emissions tests anyway.

12-17-2012, 03:05 PM
Thanks for the input. I'll let the truck heat up and see what happens then I'll try and find some anti-seize with copper. I saw that mentioned while googling late last night.

CO Hunter
12-17-2012, 07:59 PM
Most specs say hand tighten until the crush washer touches and turn another 1/2 turn, follow this exactly. Or reduce your torque wrench setting by about 50% (which is really important anytime you use anti-seize, not just on plugs).

In my opinion the 50% reduction general recommendation could be dangerous, especially on critical clamping force applications. That is a lot of reduction and in any case different lubes will have different results, way too many variables for a general statement like that.

As for the tightening 1/2 turn be careful with that as well, some may have 1/4. Check manufacturer guidelines for your plugs and head.

For you new Sequoia, Toyota should have those specs. I have always had luck going to a dealership and getting copies of the pages from factory manuals for what I work on, if I don't happen to have the FSM.

In any case, the topic of anti seize on plugs has people on both sides of the discussion regardless of plug type. The one common theme is, use it sparingly.

12-18-2012, 05:27 PM
Champion makes an anti seize specifically for spark plugs. We use it ALWAYS on aircraft engines. However this is what NGK says about using it on automotive plugs.


12-20-2012, 02:21 PM
Letting the engine warm up did the trick. Old plugs out and new ones in. Old ones were not in the best of shape. The 4 middle ones were slightly wet.

I went with the option of not using anti-seize on the new plugs.

..:: Sent from my iPhone ::..

12-20-2012, 02:31 PM
dang those puppies look worn the f out!

12-20-2012, 02:34 PM
Holy gaps... :eek:

wait, how'd you get 8 spark plugs out of an FJ Cruiser? :confused:

edit: never mind, Sequoia. :doh:

12-20-2012, 03:26 PM
dang those puppies look worn the f out!

Holy gaps...

right? engine sounds awesome now. next step is engine oil, diffs and t-case but i'd like to find a warm-ish day with no wind. having a north facing driveway pretty much blows. :rant: :hill:

wait, how'd you get 8 spark plugs out of an FJ Cruiser?

oh, if i only had the funds to make that swap. how much fun would that be? :thumb:

12-20-2012, 05:16 PM
My ignition system would have stopped sparking across that gap long ago. In fact it probably never was strong enough to do that. They look clean, though, so you got that going for ya.

12-20-2012, 05:41 PM
How many miles!? :hill: