Auto and Truck Repair and Advice
Serving the Gainesville and Hawthorne Florida Area
Spark Plugs
Spark plugs last longer today than they used to, however they still should be checked every 10,000 to 20,000 miles or so. Plug condition and color is an important indicator of how your engine is running.
Some newer cars with factory paltinum plugs are recommending 50,000 or even 100,000 mile replacement intervals! The problem is that after all that time the plugs can be almost impossible to remove. Saving a few bucks that way can really cost you in the long run if you break off a plug and have to take the heads off to fix it!
With today's electronic ignition your plugs can be worn out and your engine still run fairly well. On the flip side, if your engine isn't running right, chances are just a new set of plugs aren't going to help anything. I say this because today a "tuneup" basically consists of replacing the plugs. Period. I've worked on a lot of cars where the customer has had 3 tuneups in the past year to fix a rough run situation and has only gotten 3 new sets of plugs. The problem lay in a computer sensor or some such thing.
Avoid this problem! Your plugs should last at least 1 year or 10,000 miles. Also, if your car is running rough, take it to your regular mechanic and tell him the symptom : like " My car is hard to start in the morning" rather than just "getting a tuneup"!!!!!!!!!
HOW PLUGS FAIL
NORMAL FAILURE
Even in a normal engine, eventually the plug electrode will get eaten away by the electric arc and combustion chamber temperatures. This is the normal way a plug fails, and this takes at least 10-15 thousand miles before engine performance is affected. some newer cars advertise 100,000 miles before they need plugs.
ABNORMAL FAILURE
Plugs can fail much sooner than this due to other defective components. This may mean changing plugs more often, or repairing whatever else is wrong with the car, depending on how bad the problem is and how much you can afford to fix.
FOULING
OIL FOULING
A crusty buildup covers the tip of the plug. Light brown is minor oil fouling. Black, dirty, oily stuff is severe oil fouling. Oil fouling is caused by too much engine oil getting in the combustion chamber. Usually caused by bad valve stem seals, bad valve guides, or bad piston rings.
TRICKY CAUSES OF OIL FOULING:
Vacuum modulator (early GM, Ford) , or bad turbocharger (if so equipped).
FUEL FOULING
Plug is black and literally wet with gasoline. The spark will travel down the cone-shaped insulator rather than jump the plug gap and make spark. Cause: extreme rich run condition
CARBON FOULING
Plug is black with charcoal like deposits, but dry, no oily texture.
Cause: extreme rich run condition
MODIFIER FOULING
Whitish scaley deposit: caused by fuel additives.
OTHER CAUSE OF PLUG FAILURE:
SHORT TO GROUND
Any time the insulator is cracked, or a wet plug wire provides a path of less resistance to the spark voltage, the voltage will follow this path rather than jump the spark gap. This can make the engine idle fine, but misfire under a load or while accelerating or passing.
The Economechanix Cyber Mall
We also serve the surrounding communities of Alachua, High Springs, Hawthorne, and Newberry!
Thank you for visiting the ECONOMECHANIX WEB SITE. Please feel free to comment. We also serve the surrounding communities of Alachua, High Springs, Hawthorne, and Newberry! Gainesville has been my home since 1974, and I've loved Gvl and the Gators since I came here in the fall of 1974 to attend the University of Florida. I loved it so much I stayed and opened my car repair business. Originally it was out of the back of a 1963 Chevrolet wagon, but in 1977 a fellow mechanic and I opened an auto repair shop with actual walls, etc. I stayed in the same location for 26 years, and recently moved my operation to property I bought 15 miles east of Gainesville. I am doing most all the repairs myself now, having reduced my overhead from $1500 per month to practically nothing. I do work by appointment only. I mostly work only on my established customers cars, but I will occasionally take on new clients. E-mail me and I will either make arrangements to look at your car, or I will recommend you to someone who will.
George G. Scott, Jr.