Seize Spark Plug

[batever]

My uncle got it off.

First i tested on crashed integra. It was seize....My uncle got in there and took it off.

What he did was 3/8 and Cooper Pipe!


I did not have balls to use all the man power in spark plug. I was always afraid of the thread breaking inside.

Then He took a seize one i have in my CB

and Then He took 2 off in my friend civic.

Man 3/8 and Cooper Pipe Works wonder.

I don't get it; what did he do? I'm curious. Is Cooper Pipe a kind of plumbing thing that frees up pipes?

[XcluziveAZN]

grrr Copper or any pipe...

[deevergote]

He used leverage. That's all.

Rust penetrant isn't really useful anyway. The head is aluminum. Aluminum doesn't rust. It's merely the lubrication that is needed (and honestly, lubrication in the spark plug holes can be bad)

[batever]

He used leverage. That's all.

Rust penetrant isn't really useful anyway. The head is aluminum. Aluminum doesn't rust. It's merely the lubrication that is needed (and honestly, lubrication in the spark plug holes can be bad)

Hmm, true about aluminum not "rusting" because of the thin coating of aluminum oxide that forms on its surface--but the steel will rust more under the galvanic flow and I'm pretty sure can bond with the aluminum oxide of the head--

of course I could be wrong.

[batever]

grrr Copper or any pipe...

Ok, I understand now

[johnl]

You really can't helicoil a spark plug hole anyway... You'd need something more durable, like a timesert.

Heli-coils can work acceptably in a spark plug hole, I had one in a Fiat twin cam engine for years with no trouble. This isn't to say that other types of thread inserts might not be better than heli-coils.

If properly installed a heli-coil should be stronger than the original thread, but I don't think they are always properly installed, e.g. not exactly straight relative to the plug seating face, so the HC isn't evenly loaded when the plug is tightened down. This could place all / most of the stress on one side of the HC causing it to fail (most likely the alloy behind / supporting the HC to fail, rather than the HC itself).

One thing to keep in mind when using any kind of thread insert with a spark plug is that in most cases the insert will not conduct heat as well as the alloy of the head casting, so the spark plug tends to run hotter when a thread insert has been used. This might necessitate the use of a colder plug on the cylinder with the thread insert, especially with a high output engine...

DO NOT touch them while the engine is still warm, or you can do damage. Things expand with heat.

Which might actually help. When the head casting heats up it expands, and so the plug orifice will become minutely larger. This may reduce the force needed to loosen the plug, but it may not if the plug is not stuck due to being over-tightened, but instead is stuck due to being chemically 'welded' due to corrosion.

The issue with trying to undo the plug with the engine at operating temperature is whether or not the alloy is weaker at the higher temp (and thus at greater risk of stripping the thread out when forcing the plug), which I don't know.

[johnl]

grrr Copper or any pipe...

It's confusing because normally you wouldn't use a copper pipe as a lever because copper is very soft and bends easily. Must be a substantial copper pipe...

[johnl]

Aluminum doesn't rust.

That is impossible to disagree with...

Technically it can't rust because 'rust' is iron oxide, but aluminium can corrode even past it's protective oxide coating. The corrosion can be eloctrolytic and happens commonly when aluminium is in contact with a disimilar metal and moisture is present.

Note that vapourised water will be present in the combustion chamber, and may find it's way into the spark plug threads, especially with engines that do a lot of short trips and are not at operating temperature for a great enough % of their operating time. An engine that's been sitting around for a long time in a humid environment may get condensated water 'wicking' into the spark plug threads.

It's merely the lubrication that is needed (and honestly, lubrication in the spark plug holes can be bad)

Why can it be bad? Spark plug threads should always be lubricated...

[batever]

Why can it be bad? Spark plug threads should always be lubricated...

I think he means that the lubrication changes the effect of the torque specification (increases the stretch applied to the bolt relative to a given torque setting, and also the force against the threads in the aluminum head.) Of course if you aren't careful and go overboard on sparkplug bolt stretch or tension due to torque you can rip the threads out. But I haven't had any probs on my car using antiseize coating and torquing to the spec (13 ft lbs) given for the spark plugs, which I assume is a dry torque spec.

[deevergote]

I think he means that the lubrication changes the effect of the torque specification (increases the stretch applied to the bolt relative to a given torque setting, and also the force against the threads in the aluminum head.) Of course if you aren't careful and go overboard on sparkplug bolt stretch or tension due to torque you can rip the threads out. But I haven't had any probs on my car using antiseize coating and torquing to the spec (13 ft lbs) given for the spark plugs, which I assume is a dry torque spec.

Precisely.

[johnl]

The thread should be lubricated to reduce wear on the threads and to provide a protective film that assists to prevent the formation of oxides that might cause the plug to seize in the thread.

The torques used with spark plugs (whether wet or dry) are not very high relative to the thread size and pose no threat to the thread from a strength perspective, i.e. you'd have to torque the plug to a much greater degree before approaching the point at which the thread is in any danger of failing.

Any time a bolt or spark plug is tightened some degree of stretch will theoretically be involved, no matter how slight the torque involved. However, the torque applied to a spark plug is so slight relative to the tensile strength of the plug tube that for all practical purposes stretch is virtually non existant.

For X torque input, the tensile stress on the threads will be more or less the same whether or not the the threads are lubricated. What will reduce tensile loading (for X torque) on the threads (dry or lubed) is lubrication of the 'underhead' area of the spark plug, i.e. lubrication of and around the gasket / washer. Lubrication here means less of the torque input will be 'lost' overcoming friction in this localised area, so more of the torque is seen at the threads.

Not that a slight 'loss' of torque at the gasket / washer really matters.

[batever]

For X torque input, the tensile stress on the threads will be more or less the same whether or not the the threads are lubricated. What will reduce tensile loading (for X torque) on the threads (dry or lubed) is lubrication of the 'underhead' area of the spark plug, i.e. lubrication of and around the gasket / washer. Lubrication here means less of the torque input will be 'lost' overcoming friction in this localised area, so more of the torque is seen at the threads.

Great info in this post johnl, thanks.

The part I've quoted doesn't make sense to me though--it seems to me that lubrication on any place of contact, whether thread or underbolt/washer face will increase the tensile loading relative to applied torque, because it inherently increases the amount of boltstretch relative to applied torque. That boltstretch load is taken by the threads and by the outer face of the threaded hole. Or are you saying that that outer face of the threaded hole takes the lion's share of boltstretch force and therefore the threads take relatively little? Still, doesn't quite compute for me., because the threads are the actual points of load that make the boltstretch possible, so they have to be taking the resulting boltstretch force.

On a related note, the only place I've seen underbolt lubrication specified on this car is the cranskhaft pulley bolt, where you're supposed to apply a thin coat of motor oil to the underside of the washer that faces the crankshaft.

[Leung]

so everyone is suggesting using anti seize on spark plugs?

[batever]

so everyone is suggesting using anti seize on spark plugs?

I can't speak for everyone but I use it--the stuff that comes out silver-looking from the tube. not a lot but just enough to give a light coating to the spark plug threads. I usually wipe the threads clean with a rag, then apply the antiseize to the first threads and rely on it spreading to the rest of them as I thread the spark plug in. Although it's probably better to spread an even light coat on all the threads before even inserting the plug.

[johnl]

The part I've quoted doesn't make sense to me though--it seems to me that lubrication on any place of contact, whether thread or underbolt/washer face will increase the tensile loading relative to applied torque, because it inherently increases the amount of boltstretch relative to applied torque. That boltstretch load is taken by the threads and by the outer face of the threaded hole.

Sorry, your correct. I shouldn't write posts when I'm tired, and should have been clearer.

For light torques (as should be used with spark plugs) there will IMO be no significant difference in tension on the plug tube whether the thread is lubed or not. In practice it also makes no significant difference to tensile loading whether or not the 'underhead' area is lubed.

With higher torques (as used with say head bolts etc), then there is a significant tensile difference between lubed and unlubed. In more critical applications, lubrication is at least as imporant for reasons of consistancy of clamping force (tensile loading on the fastener shank) as it is for maximising that tensile loading (for X tightening torque exerted on the fastener head).

For spark plugs the main reason to lube threads is IMO to inhibit corrosion and possible resultant chemical adhesion between the aluminium head and plated steel spark plug threads, and to a lesser degree to minimise thread wear (though you'd need to install / uninstall the plugs a large number of times for this to be a problem, but I have seen apparently worn and loosish head plug threads).

Or are you saying that that outer face of the threaded hole takes the lion's share of boltstretch force and therefore the threads take relatively little? Still, doesn't quite compute for me., because the threads are the actual points of load that make the boltstretch possible, so they have to be taking the resulting boltstretch force.

No, but I do think the tensile force acting on the threads will tend to be uneven along the thread length, with greater loading on the threads nearer the unthreaded shank of the fasterner, and less loading further toward the other end of the threaded section. This would be more pronounced with a threaded used in a deep threaded hole than with the relatively short thread in a nut. Lubrication will I think tend to lessen but not eliminate this.

On a related note, the only place I've seen underbolt lubrication specified on this car is the cranskhaft pulley bolt, where you're supposed to apply a thin coat of motor oil to the underside of the washer that faces the crankshaft.

I think it's unusual that it's specifically stated that the underhead should be lubricated, but 'underhead' friction is a significant % of the total friction with any threaded fastener, and should always be lubricated if it is specified that the threads should be lubed (it's sort of 'taken as read' that the underhead will be lubed along with the threads).

I tend to lubricate any thread (and associated underhead areas) where a highish torque is specified or where the clamping force is obviously critical. I'd suggest, if in doubt - lubricate it.