Spark Plug Stug in #3 Cylinder...What to Do?

#1

Let me tell you all why I hate platinum spark plugs. Because people think they can leave them in forever. I’m swapping out the fouled plugs in my car and it’s pretty clear the last owner left them in for all of 100,000 miles. The kicker is that they used Autolite plugs instead of Densos or NGKs.



This leaves me doing some maintenance on my '88 Cressida that should be simpler than it’s been. I’ve already removed the first two spark plugs, but once I reached the third one, it was stuck fast. I tried everything from carb cleaner to engine lubricant to even PB Blaster with no luck.



I’ve heard some people suggest using compressed air PC duster to cool the area around the spark plug to make it contract and easier to remove. Other folks recommend using a spark plug socket that’s one size smaller than the recommended (I’m using a 21mm, so I’d use 20mm) if you have a little wiggle room, which there is.



That’s all I know. I don’t want to strip the threads in the engine block. I’ve already busted some teeth on my el cheapo click torque wrench (I’m buying a new one tomorrow), though I’ve tried to be firm and careful. Any advice would be appreciated, thanks guys.

#2

If it won’t turn one way, try to turn it a little tighter and maybe it will break free, then remove it. It sounds foolish but with other fasteners, it sometimes works although I have never tried it on a spark plug.

#3

The advice is correct. Do not try and turn it loose in one shot. Use a breakover and see-saw it very slightly back and forth. Eventually you may feel it starting to break loose and even then continue to work it back and forth.

If you succeed in getting it loose by a turn then spray it with some Blaster and allow it to soak for a while followed by see-sawing it some more. This will normally get them loose.

Use some Anti-Seize on the threads of the new plugs and this is JMHO here, but I never torque spark plugs. Overtightening plugs even slightly in an aluminum head will cause the threads to pull. This makes a thread seizure even worse.
With tapered seat plugs I always palm a 3/8" ratchet, run them down until they stop, and then just a slight nudge.
With gasketed plugs, same process. Run them down while palming the ratchet but instead of a nudge, go about a 1/6 of a turn.

This is a more trustworthy method than relying on a 1/2" torque wrench, which can be somewhat inaccurate at low torque specs.

#4

Using a lighter duty torque wrench works just fine. A light duty dial torque wrench is ideal.

#5

The vibration fro, an impact wrench can also help break it free if yo can get one in there.

As to the cooling thought, you want to cool the plug itself rather than the area around it. Cooling the area around it will only make it tighter. The hole gets smaller as it cools, larger as it heats. You could, however, carefully heat the surrounding area with a propane plumbing torch if it’s a set up such that that’s practical.

Good luck.

#6

Why are you using any type of torque wrench to remove plugs?,save the torque wrench for tightening.

#7

True, a light duty 1/4" drive torque wrench can be pretty accurate at low settings but how many people own one or can even find one to purchase?
I’ve got a German made one that is pretty pricy, deadly accurate, and I seldom use it.

Besides, I don’t even believe in some of those torque specs that are provided. On some tapered seat plugs I’ve seen specs given of 15-17 ft. lbs. and there is no way I would ever put that much stress on aluminum threads with plugs that do not have any give built into a gasket.

I’ve also seen some 15 ft. lbs. spec given for a certain plug and yet that same plug in another aluminum head engine is given a 7 ft. lbs. spec. Huge difference. The 7 ft. lbs. is a figure I can live with and is basically a nudge.

#8

The kicker is that they used Autolite plugs instead of Densos or NGKs.

I’m curious, what difference do you think it makes?

I’ve heard some people suggest using compressed air PC duster to cool the area around the spark plug to make it contract and easier to remove

That’s kinda humorous. Think about the thermal mass of the head and what your puny PC duster is going to do to cool it. In fact, any efforts on the plug should be done with the head stone cold to avoid damaging the threads.

Other folks recommend using a spark plug socket that’s one size smaller than the recommended (I’m using a 21mm, so I’d use 20mm) if you have a little wiggle room, which there is.

How does the outer diameter of the plug have anything to do with the threads sticking in the head? If you use the correct sized socket, that’s the best connection you can make to the plug. This insures you apply pressure correctly to the plug; straight and even. Jamming a smaller socket over the plug body isn’t going to help in any way.

I’ve already busted some teeth on my el cheapo click torque wrench

Why in the world are you using a torque wrench to loosen anything? Are you trying to stay below some measured amount of torque while loosening? Waste of time. Each situation is different and the amount of torque required to loosen it will vary. This is a “by feel” operation. Much better to use your own senses to gauge when the resistance is approaching damage levels.

There are various apporaches to resolving the problem. People with the certain tools will take only so much time to try and finesse it out. After that they will horse it out and deal with the consequences. Worst case, I have to put in an insert.

On the other extreme, if I had to be uber careful, I’d first decarb the motor a couple of times. Then work the plug out as far as I could, rocking it back and forth as I went. Then apply a good penetrant like B’Laster PB. Lather, rinse, repeat and in the end, it’s still a risk on removal.

#9

Yeah, I read it that way too. Using the torque wrench to break them loose will surley ruin it…

#10

Lots of good info already posted. You’ve already done the penetrating lube. I agree with tightening it a tiny bit and then going back out. Working it back and forth a little at a time will help it work out and work in some penetrating lube. Another tip is to use a 13/16 spark plug socket. That’s the standard I believe on your plug type. 21mm a little big. 20mm too small.

#11

An impact wrench and TIGHTEN it a little first. As soon as if breaks loose, soak it with penetrating oil and work it back and forth until it will finally give up and come out. The action of an impact wrench, the shock, will break loose a fastener when a steady pull will just twist it off…

Steel plugs in aluminum heads should always have anti-seize compound applied to the threads…

#12

I’ll try a 13/16 size socket and see how that works. I’ve put some PB Blaster in the cavity around the plug to let it soak overnight, so I’ll see how that works. I gave it a few taps and tried to loosen the plug and give the penetrating oil a chance to work in. It probably sounds stupid, but I wonder if applying the heat from a hair dryer to the area around the plug would help at all.

Otherwise, I’ll do what you guys suggested with the impact wrench and shock it tighter, then try to shock it looser. Is it a problem that most basic impact wrenches have a lowest torque setting of 130 ft lbs? Also, if necessary, can I use an extension piece on an impact wrench? While I’m at it, I may go ahead and apply some anti-seizure dope to the new plugs.

Thanks for all the suggestions, guys. I was looking to save a few bucks by doing this myself, but it seems after all the tools and penetrating oil, I lost out on this one.

#13

Your info about “lowest basic torque setting being 130ft lbs.” is incorrect,any I have ever used can be adjusted so low they barely move,I realise my correction of your figure doesn’t help get your stuck plug out.

#14

My shop manual says to install plugs with dry threads. Anti-seize would require modifying the torque figures. The standard plugs are nickel-plated to reduce seizing. If plated standard plugs are replaced with plugs that are not plated, all bets are off.

For example: http://www.ngkplugpro.ca/content/contentfiles/pdf/NGKSP-0907-1-Anti-SeizeonSparkPlugs.pdf

#15

Odd my Snap-on 6 point Magnetic plug socket says 20.6mm on it.

#16

hoping you have resolved this. But in the off chance you haven’t, the only experience i have had in these conditions is using hand tools lets you ‘feel’ the motion. during dissembly i never use power/air tools.

#17

I know that it’s either Urban Myth, or Gospel Truth, that one shouldn’t remove spark plugs from a hot engine; but, if the spark plug is already difficult to remove, why not run the engine long enough to heat the cylinder head to warm, and then trying to remove the spark plug?

#18

Yikes!
Put me down for Gospel Truth. I vote for cold.

#19

The kicker is that they used Autolite plugs instead of Densos or NGKs.

I’m curious, what difference do you think it makes?

If the plugs work fine then no problem…However many times using NON-OEM plugs don’t always work very well. And I can’t tell you how many times I’ve had with Autolite plugs. I pretty much stick with the OEM manufacturer…Denso or NGK for pretty much all Asian vehicles…AC for GM.

#20

I know it’s been a while, but I wanted to check in with you folks to let you know how things ended up. After being advised a number of times to do it, I used an impact wrench to loosen it up, I got that stubborn spark plug out. Luckily, it doesn’t appear that the head or the threads were damaged and another plug fit right in. Started up the car, warmed it up and took it for a spin - she runs great!

Since I was in the middle of the plug replacement job, I just used a hair dryer to warm up the area with the plug before taking a shot at it with the impact wrench. Anyway, you can’t argue with results. Thanks for your input and help, everyone, most appreciated.