Brake Pad Contamination in Cars: Meaning, Symptoms, Causes, Effects & More
What is Brake Pad Contamination?
Brake pad contamination occurs when the friction material on the brake pads becomes contaminated with oil, grease or some other foreign substance. This affects the braking performance and can cause issues like brake squeal, vibrations through the brake pedal or handlebars, reduced stopping power and overall degraded braking.
Brake pads are designed to generate friction when they make contact with the brake rotor or drum. The friction material is porous so it can grip effectively. However, if oil, grease or fluids get onto the rotor/drum and transfer to the pads, it fills those pores in the friction material reducing its ability to grip and generate friction.
Contaminated brake pads will often appear glossy or glazed compared to fresh pads. They may also feel greasy or oily to the touch. Healthy pads should have a matte finish and feel dry. Contaminated pads lose braking power so you’ll need to press harder on the brake lever or pedal to get the same stopping ability. They can also start to squeal or squeak when applied.
Symptoms of Contaminated Brake Pads
Contaminated brake pads often produce noticeable symptoms that alert drivers of an issue. Common signs of contaminated brake pads include:
Grinding or squealing noises when braking – As the brake pads wear down from contamination, the material wears unevenly. This can cause the brake pad to vibrate against the rotor, creating a high-pitched grinding or squealing noise.
Vibrations in steering wheel or brake pedal when braking – Due to uneven brake pad wear, brake rotors can become warped over time. This causes vibrations through the brake pedal or steering wheel when braking.
Uneven or pulsating brake pedal – Contaminated pads cause uneven braking forces between wheels, which drivers feel as a pulsating brake pedal that seems to pulse up and down when applying brakes.
Longer stopping distances – Contaminated pads have reduced friction, causing brakes to be less effective and vehicle stopping distances to increase. Drivers may have to press harder on brake pedals to slow vehicles.
If drivers notice any of these symptoms, contaminated brake pads could be the culprit and should be inspected immediately by a certified mechanic (Source: https://www.carparts.com/blog/common-symptoms-of-bad-brake-pads/). Addressing contaminated pads quickly reduces risks of further brake damage or failure.
Causes of Brake Pad Contamination
There are several common causes of brake pad contamination:
Oil, grease or brake fluids getting on the pads is a major cause of contamination. This can happen from an oil leak somewhere in the braking system, incorrectly spraying lubricants near the brakes, or not properly cleaning the rotor area when doing maintenance like changing the oil (Source). The oil gets deposited onto the pads, reducing friction.
Not properly bedding in new pads can lead to glazing and contamination. Bedding in pads involves gradually building up heat in them through a series of stops to properly transfer material onto the rotor surface. Skipping this step can leave pads contaminated and result in poor braking (Source).
Excessive heat is another contaminant. Overheating pads through heavy braking causes glazing, where the pads get shiny and hard. This glazed layer prevents proper contact with the rotor (Source).
Environmental contaminants like road salt, especially in winter, can also get deposited on brake pads and rotors, reducing friction and performance.
Effects of Contaminated Brake Pads
Contaminated brake pads can have several negative effects on your vehicle’s braking system and overall safety. Some of the main effects include:
- Reduced braking ability and longer stopping distances – Contaminants like oil, grease and dirt on the brake pads can greatly reduce friction between the pads and rotors. This leads to poor braking performance, longer stopping distances, and potential brake failure.
- Uneven brake pad wear – Contaminants may only affect parts of the brake pad surface, causing uneven and accelerated wear of the pads. This can lead to brake noise, vibration and reduced pad life.
- Damage to rotors and brake components – Foreign materials on the pads can also transfer onto the rotors, causing uneven rotor wear, glazing, and corrosion over time. Pistons and caliper components can also become damaged from contaminated pads.
- Safety hazards – All of the above effects mean contaminated brake pads pose a serious safety risk. Longer stopping distances make it much harder to stop in emergency situations and avoid accidents.
As per experts, contaminated brake pads result in a significant loss of braking power and friction, extending stopping distances by up to 4x normal. This highlights why it’s critical to prevent, identify and address brake pad contamination issues promptly.
How to Prevent Brake Pad Contamination
There are several ways you can help prevent brake pad contamination:
Properly bed in new brake pads according to manufacturer instructions. This involves gradually breaking in the pads through a series of light stops to evenly transfer material across the pad surface. Aggressive braking on new pads can glaze or contaminate them.
Regularly inspect brake components for leaks, cracks or damage that could allow contaminants like brake fluid, grease or oil to reach the pads. Fix any leaks promptly to avoid ongoing contamination.
Conduct regular brake inspections and maintenance according to your owner’s manual recommendations. This allows you to spot issues before they escalate.
Replace brake pads at or before the recommended replacement intervals. Overused pads are more prone to picking up contaminants from the rotors.
Avoid touching pad surfaces during handling and installation. Skin oils can contaminate pads. Follow proper procedures and use brake cleaner spray if needed.
Using high quality brake parts from reputable brands can also help avoid contamination issues.
How to Clean Contaminated Brake Pads
There are a few methods that can be used to clean contaminated brake pads, including:
Sanding Pads to Remove Glaze – Using fine grit sandpaper, you can gently sand the surface of the pads to remove any glazing or contaminants. Start with a 600 grit paper and then move up to 1000-2000 grit to get the pads smooth again. Be careful not to oversand the pads.1
Using Brake Cleaner Sprays – Non-chlorinated brake cleaners like acetone or isopropyl alcohol can be sprayed directly onto the pads and rotors to dissolve oil, grease, and other contaminants. Allow to fully dry after cleaning.2
Baking Pads to Burn Off Contaminants – Heating pads in the oven at 300°F for 30 mins can help burn away and vaporize some contaminants on the pad surface. Allow pads to fully cool before reinstalling.
When to Replace Contaminated Brake Pads
The severity of contamination determines if brake pads need complete replacement. Light contamination can often be cleaned, while deeply embedded materials likely require installation of new pads according to experts. As one Reddit user suggests, “Just make sure to thoroughly clean the rotor and calliper, otherwise you end up contaminating a second set of pads.”
Industry standards recommend replacing brake pads when they reach 2-3mm thickness. Severely contaminated pads should be replaced immediately regardless of thickness, as the embedded materials can damage rotors and reduce braking performance. An experienced mechanic can best assess when replacement is required by measuring wear and examining pad condition.
Overall, contaminated pads with surface-level debris can be cleaned and reused in many cases. But contamination that has significantly reduced pad thickness or become deeply embedded typically warrants replacement.
Cost to Replace Contaminated Brake Pads
Replacing contaminated brake pads can range in cost depending on the make and model of the vehicle, whether just the pads need to be replaced or the rotors as well, and if you do it yourself or have it done professionally at a shop.
For just a basic brake pad replacement, parts will cost between $30-$75 per pad, while labor costs typically range from $50-$150 per axle. So having the brake pads replaced on one axle by a mechanic would cost approximately $100-$300 depending on the specific vehicle and rates of the shop.
According to Jiffy Lube, the average total for a basic brake pad replacement on both axles is $200-$600.
However, if the brake rotors are warped or damaged from the contaminated pads, the cost goes up considerably. Each rotor can cost $30-$75 or more, while labor for rotor resurfacing or replacement may add another $150-$300 or more to the total job cost. This would bring the average total brake pad and rotor replacement cost to around $400-$1,000.
Overall, expect to pay at minimum $100 per axle for just brake pads, but potentially $200-$500+ per axle if rotors need work too. Going to an independent mechanic instead of the dealership can help reduce labor costs. Checking pricing from a few shops is wise to find the best deal.
Signs Your Brake Pads Need Replacement
Brake pads wear down over time and eventually need replacement. Here are some key signs that indicate your brake pads have worn down excessively and require replacement:
If the brake pad material has worn down to below minimum thickness standards, usually 1-3mm depending on the vehicle, replacement is required. This can often be inspected visually by looking through the brake caliper or drum. According to https://living.geico.com/driving/auto/auto-care/instant-expert-5-signs-you-need-new-brake-pads/, brake pad thickness below 3 millimeters typically indicates the need for new pads.
Abnormal or uneven wear patterns on the brake pads also indicate the need for replacement. This could include tapered wear on only one side of the pad, or excessive wear on the leading or trailing edge. Abnormal wear signifies an underlying issue causing the uneven wear.
In some cases, even after cleaning contaminated pads, issues like squeaking, grinding or vibration may persist. If thorough cleaning and brake maintenance does not resolve these problems, then replacement of the brake pads is likely required.
FAQs About Contaminated Brake Pads
Here are some frequently asked questions about contaminated brake pads:
What causes brake pads to become contaminated?
Some common causes of contaminated brake pads include brake fluid leaks, oil leaks from the engine, wheel bearing grease, and road tar and debris. Even something as simple as an oil spray while changing fluids can contaminate brake pads.
How do I know if my brake pads are contaminated?
The most common symptom of contaminated brake pads is reduced braking power and a spongy brake pedal. You may also notice squeaking or grinding noises when braking. Visually inspecting the brake pads will reveal a greasy film or residue on the friction surface if they are contaminated.
Can I clean contaminated brake pads?
In some mild cases you may be able to clean contaminated pads with brake cleaner or acetone. However, it’s generally recommended to just replace significantly contaminated pads, as proper friction may not be fully restored even after cleaning.
What happens if I don’t fix contaminated brake pads?
Driving with contaminated brake pads can lead to a total loss of braking power in extreme scenarios. At the very least, it will cause accelerated wear of the pads and rotors. Replacing pads early is far less expensive than damaged rotors or brake failure.
How often should brake pads be replaced?
On average, brake pads should be replaced every 30,000-50,000 miles. However, contaminated pads will likely need replacement much sooner. Routinely inspect pads for wear indicators and contamination.
Can I just replace the contaminated pads without servicing the rotors?
You should always replace brake pads in complete axle sets, and inspect rotors when changing pads. If the rotors are not damaged, they can typically be thoroughly cleaned instead of replaced to save money.