How to Check and Repair a Distributor Cap

by Contributor

If you suspect there may be something wrong with your car's distributor cap, try to see if you can repair it instead of replacing it. With a little knowledge and some elbow grease, you can repair certain problems with the distributor cap on your car. Here are some problems that can go wrong with your car's distributor cap and how to repair them.

Look for carbon tracking. If you see any, this indicates a plug wire or spark plug is increasing the resistance and you will need to replace it. Carbon tracking also conducts electricity and cannot be removed, so you should replace your car's distributor cap as well.

Check for cracks in the plastic of the rotor and distributor cap. Excessive wear and cracking means you need to replace the distributor cap with a new one.

Listen for rough idle. This could indicate a plug wire is in the wrong position and needs to be moved. You may also check the car's idle RPM to see if it is at a normal idle.

Switch spark plug wires on the distributor cap since they may not be connected correctly. It helps to have these labeled before you remove them from the old distributor cap, this way you know which spark plug wire goes where on your car's distributor cap.

Start up the engine again and check the idle RPMs. If it's up to standard then you most likely have switched the plug wires correctly and they are firing on all cylinders again.

Tip

  • check Check a Clymer or Chilton's manual for your make and model of car to see if you have the firing order correct.

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