what kills sparkplugs?

[nwcove]

plugs seem to be a very basic part.......no moving parts, simple yet crucial little things. what and makes them not do what they are supposed to do? ie fail completely?( assuming that the rest of the ignition system is working)

 

[Bondo]

Re: what kills sparkplugs?

plugs seem to be a very basic part.......no moving parts, simple yet crucial little things. what and makes them not do what they are supposed to do? ie fail completely?( assuming that the rest of the ignition system is working)

Ayuh,... Carbon build up is 'bout the only thing that totally kills 'em...
Although gettin' flooded sure knocks 'em for a loop...

 

[Frank Acampora]

Re: what kills sparkplugs?

First, your assumption that sparkplugs are simple is erronious! Although they do not have any moving parts, there is a lot of complex thought and engineering that goes into them. The magnetron that powers your microwave oven has no moving parts yet it too is quite complex from the engineering point of view.

For example: All plugs are designed to operate within a given heat range and the length and diameter of the center insulator plus the amount of center insulator in contact with the plug shell determine how cool or hot the plug will operate. Using the wrong heat range plug in an engine may lead to engine damage as well as shortened plug life.

Plugs are also designed for specific engines like the Fitch Evinrudes and for specific ignition systems like magneto or electronic. Again, using the incorrect plug may lead to engine damage and shortened plug life.

In addition to oil fouling, sometimes idling for long periods then hitting full throttle will melt accumulated deposits onto the electrodes (glazing) and stop a plug from firing. Aluminum throw-off from pistons will short plugs and general wear may cause misfiring. Sloppy installation allowing oil deposits on the outside porcelain may cause arcing through the boot to the head and misfiring. Improper torque on the plug, allowing incorrect compression of the gasket will result in incorrect plug cooling.

So: There are quite a number of factors which can cause sparkplug problems.

 

[LongLine]

Re: what kills sparkplugs?

Cracked porcelain often does a number.

Tom B.
(LongLine)

 

[Chris1956]

Re: what kills sparkplugs?

Spark plugs are worn out when the strap or center electrode (or both) is worn away. The wear comes from amperage of the spark, hot combustion gases, lean mistures and other internal engine conditions.

In the 1960, before electonic ignitions, we used to replace spark plugs every 12K miles, due to them haveing burned electrodes. In autos they now last 50K miles or more.

 

[sje0123]

Re: what kills sparkplugs?

Overly rich mix of 2 cycle can also put quite a hurting on a plug.

 

[robert graham]

Re: what kills sparkplugs?

My experience with plugs fouling is mostly from carbon from premix gas, rich fuel mixtures, lots of slow running, idling, trolling. Several years ago I bought a Harbor Freight Spark Plug Sandblaster($15), has paid for itself many times over for plugs for outboards, lawnmowers, chainsaws, etc. In fact, I never buy any plugs except for the cars at 100K miles, in which case they really ARE worn out! You need a small 2 gallon air compressor for this sandblaster, but I love it! Take plugs out of outboard and sandblast the carbon right down to the white porcelain insulator! Good Luck!

 

[nwcove]

Re: what kills sparkplugs?

i will look around for one of those plug sandblasters as i do alot (95%) of barely idling trolling/putting around. i did bring two of the plugs back to life with a propane torch....i know its not the best way, but it got me going again on a sunday afternoon when no stores were open!

 

[V153]

Re: what kills sparkplugs?

Anybody else ever crack the insulator by using a sloppy or misaligned socket?

 

[nwcove]

Re: what kills sparkplugs?

never broke a plug on the small outboards i use, but broke four plugs, more than once on a 1965 chev with headers in tight quarters. that snap of porcelin breaking was not nice when yer layin under a car, trying to fit plugs in a tight space!

 

[RandyJ]

Re: what kills sparkplugs?

Not really recommended but when I was without a sandblaster or access to a spark plug store I put the spark plug in a drill and spun it around in a bucket full of sand I got out of the lake.... a little brushing off and cleaning with starting fluid then my motor was up and running again after I set the gap.

 

[robert graham]

Re: what kills sparkplugs?

Not really recommended but when I was without a sandblaster or access to a spark plug store I put the spark plug in a drill and spun it around in a bucket full of sand I got out of the lake.... a little brushing off and cleaning with starting fluid then my motor was up and running again after I set the gap.

Drill bit, bucket of sand spark plug cleaner!...you deserve an "A" for creativity!

 

[ufm82]

Re: what kills sparkplugs?

pre-ignition will also contribute to the early death of a plug- the uncontrolled and sharp impact of the combustion can crack the insulator. Lean conditions can melt electrodes and leave metal deposits on the plug. Carbon build up isn't fatal- it can be cleaned off. And fouling is nothing worse than getting the plug wet- dry it off and it's fine. I'm of the school that does not replace plugs unless they are worn and cannot be regapped. I have gapless plugs in my 150 (or whatever they're called)- no strap, just ta center electrode and the spark jumps to the edge of the body of the plug. Other than edge wear, I can't see replacing them. My plugs are 4 years old and look identical to a new plug.
The plugs in my 2001 F150 now have 130,000 miles on them and they're fine. (platinums.) Same with my Focus- 111,000 miles and no issues. I don't replace unless they are causing issues.

 

[RandyJ]

Re: what kills sparkplugs?

Anybody else ever crack the insulator by using a sloppy or misaligned socket?

Yep.... far more times than I want to remember....

 

[geneseo1911]

Re: what kills sparkplugs?

This spring, we had problems with our forklift, UTV, lawn mower, and an old gas loader tractor. These are all stored in an unheated pole shed. The problem in all cases appears to have been a bad plug. We also had other electronics fail that spent the winter in the shed. My only explanation is that the temperature swings were more dramatic this past winter and the plugs somehow broke or corroded internally. Has anyone else seen this phenomenon?

 

[sschefer]

Re: what kills sparkplugs?

Other than a poorly running engine, the spark plugs fail when the seal between the procelean and then metal body fails. This can be hard to determine since boots rarely fully cover the porcelean area and dirt and dust can accumulate giving the appearance of soot. If you clean that off and find that the porcelean is stained brown then the plug is blowing by and should be replaced. Errosion of the center conductor and tip usually indicate a timing or fuel issue. Neither of those problems will be corrected with a plug change and need to be addressed separately. An improperly gapped plug rarely causes plug failure but may be the cause of hard starting and/or poor performance.