what makes a spark plug fail/get weak?

[nwcove]

ahhh, the lowly spark plug!! such a cheap...but crucial part! what makes them fail? you see some that have the electrodes burnt down to the porcelain that still work fine, and others that appear good but arent?

 

[JB]

Re: what makes a spark plug fail/get weak?

Evil spirits.

 

[nwcove]

Re: what makes a spark plug fail/get weak?

so does garlic tied around the powerhead help??......ohhh, wait.....thats vampires! ( maybe garlic would help with fuel prices?...stop the bloodsuckers?) lol

 

[Philster]

Re: what makes a spark plug fail/get weak?

Rich vs. lean running.

 

[5150abf]

Re: what makes a spark plug fail/get weak?

I don't know but when they decide they don't want to work nothing you do can convince them too, good thing they are cheap.

 

[Silvertip]

Re: what makes a spark plug fail/get weak?

Spark plugs fail to spark because the ignition system has an issue. They fail to spark because the electrodes have burned to a nub and the gap has opened wide. They fail to spark because they are oil, fuel, or carbon fouled due to a multitude of engine problems. They fail to spark because the dude that replaced them used the wrong plug or broke one in the installation process. They fail to spark because the spark plug wires are shot.

 

[Philster]

Re: what makes a spark plug fail/get weak?

If the diagnosis is 'spark plug failure', then the likely culprit is a combustion problem. In this case, the plug got its arse kicked.

But, there are a number of things that would keep a plug from firing. I mean, if the wire comes off, It won't fire!

But if you want to have happy plugs, have good, proper combustion.

 

[Home Cookin']

Re: what makes a spark plug fail/get weak?

I htink they're haunted, too. How else do you explain that if you removere, thoroughly clean and replace a plug with not physical damage, it still won;t work but a new one will?

 

[duke33]

Re: what makes a spark plug fail/get weak?

Strange little necessities are'nt they.

 

[Sea Rider]

Re: what makes a spark plug fail/get weak?

I htink they're haunted, too. How else do you explain that if you removere, thoroughly clean and replace a plug with not physical damage, it still won;t work but a new one will?

That's what always have asked myself, better perform a light clean and have a new gapped set at hand just in case the devil appears.

Happy Boating

 

[robert graham]

Re: what makes a spark plug fail/get weak?

I use a small spark plug sand blaster for all my plugs...cleans the carbon off right down to the white porcelain...never buy new plugs. I bought this little Spark Plug Sandblaster($15) at Harbor Freight Tools several years ago and it's paid for itself many times. Except on 100,000 mile automotive plugs, electrode erosion/wear is usually not what kills a plug. Check the porcelain electrode with a 10X magnifying glass and you may see very fine cracks in the porcelain which can provide a path for the electricity to short out the plug.

 

[Philster]

Re: what makes a spark plug fail/get weak?

Drove my old Dakota 135k miles on the original plugs. That 4.7L V8 never missed a beat. Fuel mileage was the same from the first mile to the last tank of gas.

Go figure.

Some engines kill 'em dead. Some don't. Some must be haunted, too. I'll buy that.

 

[Jlawsen]

Re: what makes a spark plug fail/get weak?

One of the most common but often overlooked reasons for plug failure when everything else is correct is seperation of the porcelain from the metal body. This causes blow by past the porcelain. Look for a dark ring at the base of the porcelain this is an indicator that the problem exists.

As Silvertip so aptly described, the problems most prevelant are those caused by other forces, (voodo not exlcuded).

 

[Sea Rider]

Re: what makes a spark plug fail/get weak?

I use a small spark plug sand blaster for all my plugs...cleans the carbon off right down to the white porcelain...never buy new plugs.

Old Champion plug blaster machines seen at service stations had a clock with a electrode to insert into plug tip, what was this for, assume for checking internal plug condition ? plugs don't last foerever specially on 2 stroke outboards, you could run them for long periods of time, but just by "still firing" doesn't mean will give you same top performance and best fuel economy/autonomy as with fresh plugs...

Happy Boating

 

[robert graham]

Re: what makes a spark plug fail/get weak?

At $3.50 each for NGK B8HS10 plugs, de-carbonizing with the sandblaster pays for itself over and over. My 1999 90C Yamaha is on it's 2nd set of plugs, and the first set wasn't warn out, just some tan color left on the porcelain, cleaned 'em good and keep for spares!

 

[Sea Rider]

Re: what makes a spark plug fail/get weak?

I'm a sandblaster big fan, but not available down here though, so doing traditional decarbon with carb cleaner or acrylic thinner dampened into a piece of coton and cleaning around threads and tip. Although visually can look as inmaculate as new after blasting, how do you know they haven't suffered any inside electrical deterioration if any compared to a new one ? at $ 3.50 and a sand blaster at hand, would clean every 50 worked hours with replacement at each 100 hours max.

Happy Boating

 

[robert graham]

Re: what makes a spark plug fail/get weak?

I've never really fouled a plug or had one fail on my yamaha outboard, but I'm sure it could happen. Some carb cleaner and an old toothbrush does a fairly good job of cleaning plugs, and the best you can do without the sandblaster. I'll bet you could order that Sandblaster from Harbor Freight and get it shipped down to you...you'll also need a small air compressor to operate it. Good Luck!