Maintenance: Tune Up Time

*** Disclaimer; Direct from IPD’s Tech Tip archive!  This tech tip contains information from previous publications.  Products mentioned may not be available or the information may not be accurate due to changes in supply, manufacturing, or part number association.  Please contact IPD Customer Support if you have further questions.

For trouble free starts and optimum fuel economy, your car needs regular ignition system tune-ups. This is a good place for a do-it-yourselfer with a few tools to spend a little time, and save some real money. The first thing to look at is the condition of the distributor cap and rotor. Remember to always have the ignition key off when working on the ignition system. Unsnap the clips, fore and aft, and have a look inside, leaving the wires connected. The cap should be clean and free of cracks, the terminals inside shiny and clean - free from corro-sion and pitting. Even if cracks are not apparent, thin black lines, known as carbon tracking, will show even minute cracks that can cause real running problems.

Check the rotor for signs of wear and pitting, and replace it if the old one is worn, cracked, or burnt. Carbon build up on the rotor is a sign that the carbon brush in the cap may be worn. If your car is fitted with a breaker type (points) ignition, you will want to check the points for wear and pitting. Turn the crankshaft until the fiber heel on the breaker points is at the highest point on the cam. Using a feeler gauge, check that the gap is correct according to the specs in your shop manual.

If the breaker points are worn, new points will be a change for the better. A bit of Hi-Temp grease on the cam will keep things running smoothly and minimize wear. If the points are pitted, the condenser, which is fit-ted to prevent excess spark, may be faulty. Condensers are inexpensive, and hard to test. The common wisdom is to replace them when they are suspect.

In any case, lubricate the distributor sparingly with 1-2 drops of light oil on the felt wick in the center spin-dle. Note that dirt and grease on the outside of the cap, and other ignition parts can also be a source of prob-lems, as this will hold moisture - the enemy of your ignition system. Keeping a clean machine can make all the difference in wet weather.

When it's time for a change, pull straight up on the rotor, and make sure that the new one is fully seated - it is keyed, so you can't put it in wrong. When you change the wires over to the new cap, do them one at a time, being certain that the cap is oriented in the correct direction. It is keyed, too, so it only fits one way. Changing the wires one at a time prevents making mistakes that will cause misfiring.

Good spark plugs are critical to engine performance, along with the other components of the ignition system. The OEM Volvo manual I have suggests replacing spark plugs at 30,000 miles. This doesn't preclude checking them more often, as they are an indicator of engine condition. Fresh plugs are well known to improve engine performance, as sharp electrodes give a better spark. Volvo suggests installing and removing plugs from a cool (not hot) engine. Plugs must be properly gapped, and tightened to the correct torque for proper operation and to avoid damage to threads. While many people recommend a dab of anti-seize com-pound for plugs in an aluminum head, bear in mind that the torque specs are for dry threads. Use care to avoid over tightening.

Some spark plugs have an R in the part number indicating that they are resistor plugs. Originally developed to reduce electrode erosion in early V8 motors, resistor plugs were found to help stop annoying radio interfer-ence. With modern high-tension leads that have spark suppression core, this is less useful. Still, with or with-out resistors, a good copper core plug is hard to beat.

Have a look at your car's ignition components soon. There's no better way to get ready for spring and summer driving - Well, that and those summer tires...

Checking Your High Tension Leads (Spark Plug Wires!)

The HT leads, or spark plug wires are the path for all the power in your car's ignition system. If they are in poor condition, your cars performance will suffer. There is no specified interval for replacement. They must be periodically tested and inspected. Replace wires that are dry and brittle, oil soaked, melted, cracked, or chafed. Watch the engine running at night.

There's nothing like darkness to bring faulty, arcing plug wires to light. Internal faults are also possible. You can test HT leads with an ohmmeter. A good wire should have 1500 to 3000 ohms resistance. Replace teh set if any wire has over 30,000 ohms resistance.

Wiggle the wire around to insure that at you don't have an internal break that is causing an intermittent connection. To avoid damage, be careful when pulling HT leads to pull on the boot, not the wire.