Spark Plug torque

[RoSPA_man]

Hi

Anytime I loosen the spark plugs, it feels too 'easy'. You get the impression they they have loosened a bit since you fitted them at 23Nm. Anyone else felt that?

 

By the way, I just went to check the torque on the Service CD and I noted the wording " Initial tightening and retightening step, 23 Nm". That would imply a specific re-tighten- maybe that's the reason they feel less tight than expected?

 

[Dick_at_Lake_Tahoe_NV]

I don't find a reference to "tighten" and then "re-tighten" in my instructions and 23nm is the correct torque value. Of course you don't want to put oil on the threads, you just want to make sure the threads are clean and dry. I've never had any reason to put anti-seize compound on Spark-plug threads either. Always make sure you start threading by hand and continue screwing in for several turns--the last thing you want to have to deal with is stripped threads from cross-threading or over-tightening.

[mbelectric]

" Initial tightening and retightening step, 23 Nm".

 

Perhaps what you are missing here is that you must first tighten the plug and crush the washer, then loosen and retighten to torque specs.

 

MB>

[Ken H.]

" Initial tightening and retightening step, 23 Nm".

 

Perhaps what you are missing here is that you must first tighten the plug and crush the washer, then loosen and retighten to torque specs.

 

MB>

Hummm…. I’ve never done it that way (on any engine). I’ve just tightened to spec, which includes the force need to compress a new crush washer.

 

To the OP’s question though – yes they do seem to feel loose, easily removable. But after all 23Nm isn’t much.

 

[IanW]

" Initial tightening and retightening step, 23 Nm".

 

Perhaps what you are missing here is that you must first tighten the plug and crush the washer, then loosen and retighten to torque specs.

 

MB>

Hummm…. I’ve never done it that way (on any engine). I’ve just tightened to spec, which includes the force need to compress a new crush washer.

 

To the OP’s question though – yes they do seem to feel loose, easily removable. But after all 23Nm isn’t much.

 

Fellas

The idea of the crush washer is to crush it when you tighten the plug, if you are going to tighten it and then loosen it and tighten it again you are missing the benefit. If you had to do that they would send it to you already crushed!

Ian

[Hall Vince]

Hi

Anytime I loosen the spark plugs, it feels too 'easy'. You get the impression they they have loosened a bit since you fitted them at 23Nm. Anyone else felt that?

/quote]

 

Yes HC.

I popped the plugs a few times and fitted a new set at 24k on my R12ST, I always felt they were not that tight, however correct torque was always applied, and they never came loose. Mind you I did expand my tool kit and one of the items was a plug socket, JIC.

CYL

Vince

[mbelectric]

" Initial tightening and retightening step, 23 Nm".

 

Perhaps what you are missing here is that you must first tighten the plug and crush the washer, then loosen and retighten to torque specs.

 

MB>

But after all 23Nm isn’t much.

 

Look, far be it from me to beat a subject to death, but try this:

 

Don't crush washer, and recheck torque after a few heat cycles.

 

Still have 23nm?

 

prob not.

 

MB>

[Lineareagle]

The point of a crush washer is to seal the combustion chamber, it has little to do with the 'tightness' of the plug.

 

You generally see crush washers on aluminum heads because it is difficult to tighten a plug in an aluminum head tight enough to seal the chamber and not get to a point of stripping out the threads.

 

23NM is sufficient to crush the washer and not strip threads, UNLESS there is something holding up the plug, dirt, damage etc.

Hence the reason to turn the plug in by hand until you are stopped by the crush washer, then torque to spec.

Personally I tighten by hand then put a wrench on and crush the washer, you can feel it crush and then get tight right away. Stop. You are probably very close to 23 NM.

 

It feels 'loose' because as soon as you get away from the washer it should turn out by hand again unless the end threads were in too far and picked up some carbon.