Spark plug installation question ~ OEM manual instruction question

[Tim Frank]

I have been working on engines of all sizes for 30+ years...strictly amateur but by staying within my limits, with pretty good luck.

So like most in here I would not have thought I needed remedial lessons in R&R of a spark plug.

But since joining the forums and reading many posts in this section, I was embarrassed/encouraged/persuaded into buying OEM manuals for each of my three O/Bs . Amongst the best $$$ I have ever spent.

To the point....I happened to glance through one manual (1975 6HP E/rude), the section on spark plug cleaning, inspection, and repair.
It included two instructions that I have never done...1) install new gasket 2) Torque to 17-1/2 to 20-1/2 ft-lbs.

Questions...does anyone replace the gasket on a spark plug when they replace it (and if so where can you buy the gaskets?)....and....
Does anyone just replace and re-tighten a plug by "feel" or do you always use a torque wrench?

I'd never dream of not using a torque wrench to tighten the bolts on connecting rod caps...or anything internal....the flywheel nut...and lots of others.
But I always figured as long as I get a plug tight enough and don't strip it, it should be fine.

Fool's paradise?

 

[oldcatamount]

Re: Spark plug installation question ~ OEM manual instruction question

I do mine "by feel" and I've never seen a spark plug gasket before.

 

[Tim Frank]

Re: Spark plug installation question ~ OEM manual instruction question

It's just what they call that loose ring....I've never even tried to get one off the plug....

 

[dew2]

Re: Spark plug installation question ~ OEM manual instruction question

I tighten mine by feel also the spark ring at one time, all plugs came with one,the old were terribly hard to remove,I now days pay no attention to them.

 

[Sixmark]

Re: Spark plug installation question ~ OEM manual instruction question

The gasket they refer to is actually the loose metal ring that Tim Frank mentioned, it's technically a crush ring. They actually did sell replacement crush rings for spark plugs years ago, however I think you would be hard pressed to find a parts outlet that does now....but you might. I have had plugs out before that had the rings on them and reinstalled them with no problems.

Do NOT!!! remove the ring and then reinstall the plug however!!!

 

[Cofe]

Re: Spark plug installation question ~ OEM manual instruction question

In auto mechanic school I was taught to always torque spark plugs in aluminum heads. The reason being, that every time you over torque one by "feel" with your calibrated arm, the aluminum threads pull a little bit. Then there will come the time when they strip..

As far as the crush ring goes, a person is supposed to replace them, but I never have. Come to think of it, I have never seen a plug have blow by from a faulty crush ring.

 

[Tim Frank]

Re: Spark plug installation question ~ OEM manual instruction question

In auto mechanic school I was taught to always torque spark plugs in aluminum heads. The reason being, that every time you over torque one by "feel" with your calibrated arm, the aluminum threads pull a little bit. Then there will come the time when they strip..

Now that makes sense!
Thanks.

 

[robert graham]

I always just tighten my spark plugs "good and snug", never have replaced the metal washers, sometimes with aluminum heads use some silver metallic anti-seize compound. On my 1999 C90 still running the original plugs....but I do use a Harbor Freight spark plug sand blaster to remove all carbon...from all my spark plugs for cars, mowers, blowers, outboards....a great little unit for $15....

 

[GA_Boater]

Topic is over three years old. :doh: