Spark Plug Torque--Not By Hand!

[Jason2tpa]

Anybody have a recommendation on a "light" torque wrench? My lowest torque setting is 10 lb ft. Many bolt requirements are less than that. Maybe I am looking in all the wrong stores...

I recently saw one in O'rielys. It had a 1/4" drive with ft-lb torque starting at 1. Think it was $25. But if you look on ebay you'll find cheaper.

[pstephens46]

Rodbolt discussed this at one time. Referred to them as fire rings. I believe he did say to replace.

[99yam40]

the big question is where do you find replacements without buying new plugs?

[pstephens46]

the big question is where do you find replacements without buying new plugs?

The question is whether or not anyone has ever had issues because of re-use?
I never have....

[Jason2tpa]

We know the purpose of the crush ring is to provide a seal between head and plug. The even bigger question is, IS the seal compromised when mounting the plug for 2nd time and thereafter? And if so, is the amount of compression lost significant enough to worry about?

[fairdeal]

We know the purpose of the crush ring is to provide a seal between head and plug. The even bigger question is, IS the seal compromised when mounting the plug for 2nd time and thereafter? And if so, is the amount of compression lost significant enough to worry about?

here's what NGK themselves have to say about installing "Reused" spark plugs:

if you are not using a torque wrench, the "tightening angle" is reduced

(presumably, because the gasket has already been "crushed")


The illustration shows a substantial reduction for the standard gasket.

Less of a reduction for the solid copper type gasket.

And naturally, no change for the gasket-less taper seat style plug.

[boscoe99]

here's what HGK themselves have to say about installing "Reused" spark plugs:

if you are not using a torque wrench, the "tightening angle" is reduced

(presumably, because the gasket has already been "crushed")


The illustration shows a substantial reduction for the standard gasket.

Less of a reduction for the solid copper type gasket.

And naturally, no change for the gasket-less taper seat style plug.

You are always making way too much sense.

[cpostis]

You are always making way too much sense.

Too bad the gaskets in the diagram are copper, not the aluminum "crush" gaskets used on most plugs for Yamaha outboards.
The aluminum gaskets are avaiable from Champion @ 15 cents a piece.
https://www.sparkplugs.com/N678-Cham...p26421.aspx://

[TownsendsFJR1300]

Too bad the gaskets in the diagram are copper, not the aluminum "crush" gaskets used on most plugs for Yamaha outboards.
The aluminum gaskets are avaiable from Champion @ 15 cents a piece.
https://www.sparkplugs.com/N678-Cham...p26421.aspx://

That link doesn't work...

I don't believe the gaskets are aluminum(I may be wrong), but steel (appears the same finish as the plugs themselves).

With that said, I've replaced (98% small engines) with crush-able gaskets MANY times without an issue (by hand yet). I talking 3,600 RPM large 4 strokes (single cylinder, up to 10HP) to 8,000 RPM single 2 strokes.

Never had one leak, nor thought ANY about it...

[fairdeal]

actually, the little NGK "cartoons" ARE referring to the standard gaskets

the copper washer and taper seat are separately addressed there.



I can believe its aluminum

certainly a complicated shape

I've always marveled that they get it on there, but it doesn't want to come off....

[TownsendsFJR1300]

I just put a magnet to an old Champion lawn mower spark plug with gasket (looks the same as pictured).

My magnet DOES GRAB gasket pulling it up. (against gravity)

[robert graham]

The question is whether or not anyone has ever had issues because of re-use?
I never have....

My motor is a 1999 and has the original plugs and washers....I sandblast any carbon off plugs a couple of times a year....plugs look and operate just like new ones and no issues with the washers either.....also, "good and snug" seems to work well.....spark plugs ain't brain surgery to me....hand tighten then snug with a wrench....

[cpostis]

actually, the little NGK "cartoons" ARE referring to the standard gaskets

the copper washer and taper seat are separately addressed there.



I can believe its aluminum

certainly a complicated shape

I've always marveled that they get it on there, but it doesn't want to come off....

I's something how some people can solve "Rubiks Cube" in moments and others can't ever?
On NGK "crushable gaskets" are three stamped flats in the ID (others have four). These must be lined up in the spark plug threads properly in order to unthread from the plug. Here's a video that shows the gasket being removed and contains ferrous metal (click on image).

[IMG]15375246_1736673533326855_2560081111514349568_n by Charles Postis, on Flickr[/IMG]

I normally don't worry about the gasket, but if you remove and re-install several times, why not change the 15 cent gasket? You guys change your gear case drain screw gasket every time, don't you?

Now, do you guys know the most important role in a "crushable gasket"?
Heat transfer!
Take a gander at this.

https://www.ngk.de/en/technology-in-...and-heat-flow/

40% of heat removal from the cylinder to the head is through the "crushable gasket". It increases the surface area of the transfer area. I know you guys always install your plugs and gaskets oil free, clean and dry, right? The hotter the plug range the more critical the heat transfer area is.

[99yam40]

Seems like I remember oil seepage around plugs before on 2 strokes.
I do not believe you would need to worry about leaking compression thou

[boscoe99]

For a copper gasket what should the condition of the metal be in for it to seal properly?

Does anyone take the time to heat treat (anneal) their copper gaskets to ensure they seal and transfer heat as they are supposed to?

Stuff on the surface might appear to be simple but in reality it is not always so. There is a lot more going on in a spark plug than simply making a spark.