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How the Distributor Works

How the Distributor Works

Advancements in engine designs have done away with the distributor on modern vehicles, with distributors being replaced with simpler individual coil packs. However, there are still many cars and trucks on the road that use distributors to transfer the electrical charge to the engine’s spark plugs.

How the Distributor Works

Many people don’t even have a basic understanding of how their auto engine works, they just know they turn the key and the vehicle starts. However, in vehicles designed to use one, the distributor is one of the key ignition components that allows the engine to not only run, but run smoothly.

A distributor functions by taking the electrical current sent through the ignition coil from the vehicle’s alternator and “distributing” the voltage to each terminal in the distributor cap, in sequence. The distributor then transfers the electrical current sent from the coil to the spark plug in each engine cylinder at the precise time. That in turn causes the combustion of the fuel and oxygen mixture in the cylinder chamber that moves the piston that then turn in rotates the drive shaft and the wheels turn. As you can see the importance in this chain of events, without the spark being delivered properly, the engine will not perform well and many not even run at all.

How to Change a Distributor

It is not an overly complicated task to replace a distributor. However, be sure to seek the assistance of a qualified mechanic if you are not confident in your skills. Once you have determined the distributor requires replacing, follow these steps:

1) Locate the distributor
Typically near the middle of the engine compartment, the distributor will be cylindrical in shape with a black or gray plastic cap. The cap will resemble a crown with a series of nipples on the top, arranged in circle, that the spark plug wires are connected to.

2) Remove the wires
If you are replacing the cap as well, before pulling the wires, place a piece of masking tape on each wire and write a number on each piece of tape that corresponds with the position on the cap. Alternatively, remove one wire at a time and place it in the same position on the new cap. Note there is one additional wire in the middle of the cap that connects to the ignition coil.

4) Remove the distributor cap
Unhook the clips and screws that hold the cap to the distributor body. The clips can easily be removed from the brackets with your fingers. Screws will need to be removed with a Phillips head screwdriver by turning the screws counter clockwise, or to the left. Remember the phrase, “lefty loosey; righty tighty.”

5) Mark the placement of the distributor and rotor on the engine block with a crayon or piece of chalk.
Pull the distributor out of the engine block taking care not to rotate the engine with the distributor removed or the timing may be thrown off.

6) Remove the rotor
The rotor looks like a blade situated underneath the distributor cap. Wiggle the rotor gently in a back and fourth clockwise and counter clockwise manner until it comes lose. Note that on some models the rotor is connected with screws below the rotor blade. Transfer the marks from step five to the new distributor.

7) Install the new rotor
Align the marks transferred from the old rotor and distributor with those on the engine block. Now perform the same steps used to remove the old rotor in the reverse manner.

8) Install the new distributor cap
Make certain the new cap is in the same orientation as the old one. Once the cap is installed, check to confirm each spark plug wire is securely attached to the cap.

9) Test the new distributor
Start the engine. If it purrs like a kitten you are good to go. If the engine runs rough, it is most likely due to a lose spark plug or coil wire. Check both ends of each wire again to see if one is loose. If the engine misfires, it is an indication the timing needs to be reset.

Are Used Parts Cheaper?

If you need to replace a distributor you may be tempted to buy a used part to save a little money. However, buying used parts is often like rolling the dice. While buying a used nonmoving part, such as a door panel or bumper, will save you some coin, moving parts are a different story and generally not worth the risk. Even if a used part looks to be in good condition you can never know for sure how much life it will have left. While a used part may last for years, it may fail in a week and you will then have to spend more money to replace the part a second time and also have to perform the labor to change the part twice.

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