Reading spark plugs
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==Magnifier== | ==Magnifier== | ||
It's imperative that a light source with a magnifier be used to read plugs, because the plug insulator at the deepest point is one of the things that is looked at. If the light source isn't uniform from reading to reading, the slight coloring differences can be misread. The idea is to have repeatable conditions. | It's imperative that a light source with a magnifier be used to read plugs, because the plug insulator at the deepest point is one of the things that is looked at. If the light source isn't uniform from reading to reading, the slight coloring differences can be misread. The idea is to have repeatable conditions. | ||
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Look for a colored ring at the base of the porcelain. The color will vary depending on the type of fuel: Unleaded E10 pump gas will leave very little color because of the additives like detergents, as well as the methanol. If using 108-110 octane race gasoline, these fuels will leave a tan color while the C17 and higher octane fuels will leave an almost gray fuel ring. | Look for a colored ring at the base of the porcelain. The color will vary depending on the type of fuel: Unleaded E10 pump gas will leave very little color because of the additives like detergents, as well as the methanol. If using 108-110 octane race gasoline, these fuels will leave a tan color while the C17 and higher octane fuels will leave an almost gray fuel ring. | ||
| − | If you study the ring you will see that it starts to show color just below the base of the ground strap, this is caused by the shielding | + | If you study the ring you will see that it starts to show color just below the base of the ground strap, this is caused by the shielding effect of the strap leaving that portion cooler thus showing the most color. The ring will develop from each side and form a full circle of correct color as you get closer to the correct tune up. |
If you look down into the bottom of the porcelain and you detect a thin oily deposit you are seeing oil from the combustion chamber caused by either worn or improperly seated rings. This may also be seen with a new engine that hasn't fully seated the rings yet, just don't confuse this with the fuel ring. | If you look down into the bottom of the porcelain and you detect a thin oily deposit you are seeing oil from the combustion chamber caused by either worn or improperly seated rings. This may also be seen with a new engine that hasn't fully seated the rings yet, just don't confuse this with the fuel ring. | ||
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[[File:Rich18.jpg]] | [[File:Rich18.jpg]] | ||
| − | Black or brown | + | Black or brown specks: This is an indication of detonation which is caused by ignition timing that is too advanced for the air/fuel ratio or octane of the fuel. Detonation (an undesirable, uncontrolled combustion of the air/fuel mixture after the ignition event) causes the boundary layer of air within the cylinder to be disrupted, which in turn causes the components and surfaces within the cylinder to absorb heat from the combustion process and increase in temperature. The black spots are the result of oil deposits bypassing the piston rings during detonation and being fused onto the porcelain by the increased cylinder temperatures. Tiny beads of grey/silver material apparent on the porcelain are melted piston. Reduce the ignition timing, richen the mixture, increase the octane of the fuel or a combination of all of these to prevent this situation. |
| − | The black spots are the result of | + | |
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{{Warning}}Do not underestimate the damage this condition can cause your engine. Correct this by whatever means necessary. | {{Warning}}Do not underestimate the damage this condition can cause your engine. Correct this by whatever means necessary. | ||
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