Seven Spark Plug Myths Busted

Seven Spark Plug Myths Busted

If it fits, it will work. Spark plugs can be changed when the engine is hot. The thicker the wire means more of the fire! ... False, all false. These are all spark plug myths. We bust these and a few others in this month's look at spark plugs.

If it fits, it will work. 
False. Even if a spark plug fits in the hole in the head and the correct heat range, the electrodes may not be designed for that ­specific engine. The wrong plug electrode design can affect the flame front inside the combustion chamber and even increase the compression ratio. Always consult a catalog before using an old cross-reference chart. 
Spark plugs can be changed when the engine is hot.
Changing the plugs while the engine is hot is a big ­no-no. Even removing the plugs while the engine is hot can damage the plugs and the head due to differing rates of thermal expansion. Always wait until the engine is cold. 

The thicker the wire means more of the fire!
False. The actual core of a spark plug wire, which carries the spark, is small and its resistance is specified by the OEM. The girth of a spark plug wire is the insulation and shielding. Performance wires that are thicker can offer greater electromagnetic shielding for ­running performance ignition boxes. Racing plug wires offer more thermal protection and ­abrasion resistance.
The color matters.
Yes and No. A plug that has racked up the miles should have a brownish or greyish color on the insulator and electrodes, but some gas additives have been known to turn fresh insulators blue, pink or purple. Pay more attention to the deposits and where they occur to determine if there is a problem. 
Measure, gap and grind.
Never on modern applications. Modern precious metal, fine wire and tip-to-tip plugs should be handled with extreme care. You should never try to change the gap of the plug unless the manufacturer advises it. Trying to measure or clean the plug will cause damage and ­misfires.     
You need to put anti-seize on the threads.
False. Most spark plugs come from the factory with a coating or plating that is designed to prevent galling of the threads. Applying a coating of anti-seize will only lead to incorrect torque readings. Use of anti-seize can increase torque values by 20 percent. 
Corona stains are a sign of an incorrect heat range or blowby.
No. Corona stains on the exposed ceramic body are normal. Corona stains are caused by the high amount of static electricity attracting particles of oil and dirt to the body of the plug — not blowby gases or thermal distress.

You May Also Like

Top 5 Tools: Riley Bender, Riley’s Repair

Top 5 Tools Riley Bender, Owner Riley’s Repair Brackney, PA Riley’s top 5 favorite tools are: Craftsman 27-Piece Screwdriver Set “These tools have been very useful in engine repair.” Channellock’s 12” Tongue and Groove Pliers “These pliers are helpful in removing hose clips on the tubes in cars.” Pittsburgh 40-Piece Socket Set   “It is

Top 5 Tools

Riley Bender, Owner
Riley’s Repair
Brackney, PA

Riley's top 5 favorite tools are:

Craftsman 27-Piece Screwdriver Set
“These tools have been very useful in engine repair.”

Channellock’s 12” Tongue and Groove Pliers
“These pliers are helpful in removing hose clips on the tubes in cars.”

Top 5 Tools: Steve Coffell, Auto World, Hazelwood, MO

Steve Coffell, a technician at Auto World in Hazelwood, MO, says his Top 5 Favorite Tools are: Related Articles – Streamlight Launches Stinger Color-Rite Light – Streamlight Adds Two New Work Lights – New Master Series HL1000 and PL 500 from NEBO Lights   OTC Genisys Touch – Quick scan, bidirectional control Snap-on VANTAGE Pro – Easy-to-use

Wheel Bearing Adjustment Tools & Equipment

A wheel bearing that’s out of adjustment can reduce bearing life and can affect more than just the bearing. It’s important to adjust the wheel bearing endplay to the proper specifications. If the bearing set is adjusted too loose or too tight, it can cause the bearing to fail prematurely. There are a few types of assemblies, so using correct procedures and tools will ensure a comeback-free wheel bearing installation.

What R-1234yf Means for Service, Equipment, Safety

For shops, R-1234yf means several new procedures, a certification and new equipment in order to properly handle these new systems. Why the difference in handling and servicing R-1234yf systems versus R-134a? Flammability.

Top 5 Tools: Daniel Sjobeck, Roseville Auto Repair

Daniel Sjobeck, tech Roseville Auto Repair Roseville, MN Related Articles – Snap-on Butane Torches Offer Unmatched Versatility – Milwaukee Provides Improved Performance with Die Grinders – OTC Debuts New Hub Oil Seal Puller Set A good toolbox. You can have the best of everything, but it’s no use if you cannot find it. Power Probe

Other Posts

Snap-on Lights the Way

Snap-on lights provide techs illumination in dark spaces.

Inductor Max: Experience the Power of Induction Heating

Rapidly heat components while eliminating the dangers of an open flame.

Hunter Center-Clamp Tire Changer Adjusts to 3 Heights

The new tire changers, which include a mobile version, meet the need for shop productivity in limited space.

ProMAXX Tool Provides Solution for FCA U90 Emissions Recall

Bullit adaptable bolt repair ProKit and thread repair kit helps technicians quickly perform repair.