Squealing Sound Under The Hood? Could Be A Bad Distributor

In older vehicles, the distributor plays a vital role in the ignition system of an internal combustion engine. It manages the firing of the ignition coil, assists with ignition timing, and sends high voltage to the spark plugs. The distributor is composed of a cap and a rotor. It is responsible for routing the voltage to the spark plugs in the correct firing order.

Parts Of A Distributor

Inside the distributor, the rotor attaches to the distributor shaft. As the rotor turns, it establishes the electrical path from the coil to the individual spark plug wires, which are attached to the cap. The distributor cap also protects the internal parts of the distributor.

The distributor shaft rotates in bearings. If you’re noticing a ‘screaming’ sound coming from under your hood, the bearings may be failing.

Note: With the advent of individual coil packs, most vehicles from the late 1990s to today don’t have a distributor. The distributor system is mostly found in older models. So, if you’re car is newer an you’re experiencing squealing sounds, you’ll have to check elsewhere. (Learn more here about the benefits of replacing the distributor in your older car)

Signs Of A Failing Distributor

Knowing the signs of a failing distributor can save you from unexpected breakdowns and expensive repairs. Here’s what to watch for:

1. Squealing Sounds: A Key Indicator

As mentioned above, a significant sign of a worn distributor is squealing sounds from the shaft bearings. This noise is distinctive and different from other sounds under the hood. Some have described it as a screaming or yelling sound. On inspecting the distributor, you might find a build-up of grease, grime, and other contaminants, indicating that the bearings are failing.

2. Symptoms Of A Bad Distributor Cap

A bad distributor cap will likely cause hard starting and may create issues like engine misfires and stalling. A bad distributor cap can even prevent the car from starting at all due to a lack of spark. There are a few other clues:

• If your vehicle shakes uncontrollably, especially when starting or changing gears, a defective distributor cap might be the cause.
• The cap is bad if you can see a crack in the cap, even a hairline crack.
• Inspect the inside of the cap. It’s time for a new cap if the contacts are excessively worn.

Check the distributor shaft for excessive play if the contacts inside the cap are worn. Worn bearings can cause the rotor to rotate in a larger circle than normal, which wears the cap contacts. If there is any play, the shaft bearings should be replaced. 

Distributors And Distributor Caps From Karl Kustoms

A distributor’s health is essential for the smooth running of the engine. Squealing sounds under the hood are often indicative of a failing distributor. So, if you’re working on a classic or maintaining an older ride, recognizing the sounds and symptoms of a failing distributor is important.

If you notice any of these signs, particularly the squealing noise, Karl Kustoms is ready to help you find a replacement distributor. Our team is made up of hot rod, racing, and classics enthusiasts. Our machine shop, custom shop, and service shop crews specialize in restoration, custom upholstery, custom painting, bodywork, accessory installations and more. Put our know-how to work for you! Check out the charts below to find the many distributors and distributor parts we offer – and order today.