Search results
Typical lead erosion causes the surface of the ground electrode to become thinner, and the tip of the electrode looks as if it has been chipped. This video describes in detail the best process to examine a spark plug and assess its condition.
- Careers
Find a job at Niterra. Niterra employees receive a range of...
- Racing
Application for the 2025 race season is open from 8/1/2024 –...
- Oxygen Sensors
NTK is the world’s largest supplier and manufacturer of...
- Ignition Coils
The NGK Difference. A ll NGK ignition coils must pass...
- Sensor Parts
NTK offers a full line of driving sensors for the automotive...
- Non-Automotive Ignition Parts
Our line for non-automotive applications includes spark...
- Wire Sets
NGK ignition wire sets are engineered to meet strict OEM...
- Technical Training
Only the plug number is labeled on the spark plug, while...
- Careers
Blisters on the insulator tip, melted electrodes, or white deposits are signs of a burned spark plug that is running too hot. Causes can include the engine overheating, incorrect spark plug heat range, a loose spark plug, incorrect ignition timing or too lean of an air/fuel mixture.
Spark Plugs: Would it be OK to use needle nose pliers on the side wire to adjust plug gap? I tried using one of those loop tools made for precious metal plugs, and all it did was bend. Unfortunately for me my local auto parts store only carries these and the coin style.
- (5.6K)
- Olivia Marsh
- Remove the spark plugs. Refer to your vehicle service manual to determine the location of your spark plugs, how many there are, as well as instructions on pulling them out.
- Check for soot. When you first begin to examine a spark plug, check for any black soot on the insulator or even the central electrode. Any soot or carbon build up indicates the engine is running rich on fuel.
- Check for white deposits. Any white deposits (often ashy looking) on the insulator or central electrode often indicates excessive oil consumption or fuel additives.
- Check for white or tan blisters. Any white or light tan blisters with a bubbling look to them can indicate an issue with the fuel or the use of fuel additives.
- Normal
- Deposits
- Wet and Dry Fouling
- Lead Fouling
- Breakage
- Melting
- Lead Erosion
- Erosion, Corrosion & Oxidation
- Overheating
Appearance: A light tan/gray or brownish color, along with very little electrode erosion, indicates optimal operation conditions, including a healthy engine and correct spark plug heat range.
Appearance & Symptoms: The electrodes—center and ground—are covered in an ashy coating. As a result of this masking of the electrodes, your engine may experience a misfire. This build-up of combustion deposits can eventually (but not usually) fill in the space between the two electrodes. Possible Causes: Oil leaks, poor fuel quality.
Appearance & Symptoms: Dry fouling (top) appears as sooty, black build-up. Wet fouling (bottom) has a wet, sometimes oily appearance. Both conditions can create poor starting and misfiring. Possible Causes: Depending on whether the spark plug is coated in oil or fuel, wet fouling can be symptomatic of a compromised head gasket, poor control from yo...
Appearance & Symptoms: Lead fouling can only occur in applications that use leaded gasoline, such as racing engines. Lead fouling generally shows up as yellowish brown deposits on the spark plug’s insulator nose. Lead fouling can cause your engine to misfire only at high-rpm and under hard acceleration. Possible Causes: This condition commonly occu...
Appearance & Symptoms: The insulator around the center electrode may be broken (see left) or the ground electrode may be bent. Again, you will likely experience misfire and some power loss under these conditions. Possible Causes: If the insulator is broken, it may be the result of sudden thermal expansion or thermal shock caused by extreme temperat...
Appearance & Symptoms: In this case, the center or ground electrode is melted or scorched, and your engine may be experiencing some power loss. Possible Causes: According to NGK, melting often results from loose installation, which prevents the plug from properly transferring heat from its tip. But melting may also indicate unusual heat or hot spot...
Appearance & Symptoms: The tip of the ground electrode looks chipped and its surface may be thinned. Possible Causes: Another condition unique to leaded gasoline, this condition is caused by lead compounds that react chemically with the electrodes at high temperatures. This makes the electrode material (nickel alloy) weak and brittle. This is cause...
Appearance & Symptoms: A plug with a combination of erosion, corrosion, and oxidation will have pitted and rough electrodes and may even have a green cast if the oxidation is heavy. These conditions can result in increased, improper spark plug gap and yield poorer performance. Possible Causes: Typically, these conditions occur over time as lead in ...
Appearance & Symptoms: The insulator will have a glazed white appearance and may have small black deposits. There may also be abnormal electrode wear, and you will likely notice a loss of power at high speeds or under high engine load. Possible Causes: Overheating may occur from over-advanced ignition timing, poor cooling system efficiency, lean ai...
Jan 31, 2018 · The tip of the plug gets hot enough to burn the deposits off of the plug. You want that tip to be about 1,600 degrees so it burns deposits off the tip, or else it fouls.
People also ask
How do you know if a spark plug is too hot?
How do you read a spark plug?
What does a rich spark plug look like?
How do you know if a spark plug is bad?
How do I know if my spark plugs are pig-rich?
How do I know if my insulator firing nose is good?
A good spark plug should have a light brown or tan color on the tip of the electrode, indicating that it’s functioning optimally. Any other color or mixture of colors shows there’s something wrong.
