Does your car make an unsettling grinding noise when you press down on the accelerator pedal? This worrisome sound usually signals an underlying problem, but determining the exact cause can be challenging.
What exactly is causing the grinding noise when accelerating, and how can you diagnose and fix the problem yourself or know when it’s time to take your car to a professional mechanic?
This detailed guide will overview the main causes of grinding noises from your car when accelerating, how to pinpoint the root of the issue through diagnostic tests, steps for DIY repairs or when to seek help from a certified technician, and tips to prevent future grinding noises from occurring.
We’ll cover everything you need to know about:
- Common causes like worn wheel bearings, CV joint damage, and brake issues
- Inspecting your wheels, brakes, axles, and tires to diagnose the problem
- Step-by-step instructions for replacing a wheel bearing or CV joint
- When it’s best to have a mechanic complete the repairs
- Preventative maintenance to avoid grinding noises when accelerating
Table of Contents
What Does a Grinding Noise When Accelerating Mean?
Hearing a grinding noise when pressing down on the gas pedal usually indicates one of three underlying issues:
Worn Out Wheel Bearing
The wheel bearings allow the wheels to spin freely along the axle shaft by reducing friction. Over time, the constant motion wears down the steel ball bearings inside the hub assembly. As the wheel bearing gets progressively looser and more damaged, you may hear grinding noises when accelerating or turning corners. The sounds tend to get louder and occur more frequently as the wear worsens.
Replacing a worn out wheel bearing before it fails completely is critical. Driving with a collapsed bearing can cause the wheel to lock up while moving, leading to potential accidents or injuries.
Damaged CV Joint
Your car relies on CV or constant velocity joints to transfer power from the transmission to the wheels when turning. The CV joints are protected by rubber boots that can crack or rip over time. When the boot fails, contaminants enter the joint and cause internal damage.
A damaged CV joint may produce clicking, snapping, or grinding noises when accelerating or making turns. The sounds tend to worsen when pivoting at low speeds. Leaving a damaged CV joint unchecked can lead to complete failure and make the car undriveable.
The brakes can also produce grinding noises when accelerating if the brake pads are excessively worn down or contaminated with debris and dirt. The buildup of brake dust and particles on the rotors can cause a metal-on-metal grinding sound when driving, even if the brakes are not engaged.
Improperly lubricated brake components may also grind from the added friction. Any brake related grinding noises warrant immediate attention to prevent complete failure and ensure safe braking ability.
How to Diagnose the Cause of the Grinding?
Pinpointing whether the grinding issue stems from a damaged wheel bearing, CV joint failure, or brake problems involves a thorough inspection and test drive.
Visually Inspect Tires, Brakes, Undercarriage
Start by examining all four tires and looking for any visible damage, uneven tread wear, or leakage from the wheel bearings. Inspect the brake pads and rotors for extreme wear or thick buildup of debris on the rotors. Examine along the axles and undercarriage for torn CV boots or signs of leakage.
Jack Up the Car and Spin the Wheels
Safely jack up each corner of the car so the wheels are off the ground. Have someone spin each wheel slowly by hand while you listen from the wheel well area. Pay attention to which area the grinding sound emanates from. A wheel bearing grind will be loudest directly from the troubled bearing.
For CV joints, you may hear clicking or popping noises when spinning the wheels. The sounds will increase when pivoting the wheel from side to side.
Test the Brake Pedal and Parking Brake
Press down on the brake pedal while stopped and drive at low speeds to listen for grinding noises. Also engage the parking brake while stationary to check for issues. There may be a grinding sensation through the brake pedal from contaminated brake components.
Test Drive with Turns and Acceleration
Take the car for a thorough test drive, accelerating from stops, making tight turns, and braking at various speeds. See if you can isolate whether the grinding occurs when stopped and accelerating, when turning corners, when braking, or a combination. This will help narrow down brake problems versus wheel bearing or CV joint issues.
Fixing a Wheel Bearing Making Grinding Noises
If diagnostics pinpoint the grinding to a failing wheel bearing, follow these steps to replace it yourself or have a professional mechanic complete the repair:
Overview of Wheel Bearing Replacement
Replacing a wheel bearing is moderately challenging for DIYers. The repair involves removing the wheel, brake caliper and rotor, disconnecting the bearing assembly, pressing in the new sealed bearing, and reassembling the brakes and wheel.
Wheel bearing kits with instructional videos can help guide home mechanics through the process. You’ll need automotive tools like jacks, socket sets, a hammer, pry bar, brake cleaner, and torque wrench. Always refer to the manufacturer service manual.
If tackling the repair seems too complex, seek help from a certified mechanic. The average cost for professional wheel bearing replacement ranges from $150-$300 per bearing.
Step-by-Step Wheel Bearing Replacement Instructions
Follow these key steps to safely replace your grinding wheel bearing at home:
- Loosen the lug nuts and jack up the vehicle. Secure on jack stands.
- Remove the wheel. Detach the brake caliper and tie it up out of the way.
- Disconnect the brake rotor and take it off. Remove any grease caps or dust covers from the hub.
- Unbolt the wheel bearing assembly. Use a hammer and drift punch to knock it loose if stuck.
- Thoroughly clean the hub contact area. Apply thread locker to the new bearing bolts.
- Install the new sealed bearing and tighten the mounting bolts to the specified torque.
- Reinstall the brake rotor, caliper, brake pads, and wheel. Lower the vehicle.
How to Fix a Bad CV Joint Causing Grinding?
For grinding noises traced back to a damaged CV joint, follow this overview for replacing the faulty joint yourself or having a shop do it:
What’s Involved in CV Joint Replacement
Replacing a CV joint requires detaching the axle shaft, removing the boot clamps, uninstalling the joint from the shaft, cleaning and prepping the parts, and installing the new joint with fresh boot.
The intricate procedure and special tools required makes CV joint replacement more suited for professional mechanics. The average cost is $350-$550 per joint. DIYers can tackle it to save money if they have automotive experience.
Step-by-Step CV Joint Replacement Instructions
Use extreme care when working around the axle shafts. Wear protective gear and follow these steps:
- Loosen the wheel lug nuts slightly before jacking up the car. Raise and secure the vehicle on jack stands.
- Remove the wheel for full access. Detach the suspension components if needed.
- Use hose clamp pliers to remove the rubber boot clamps on the outer and inner joints. Slide the boot back.
- Unfasten the locking bolt on the CV joint. Use a slide hammer puller to detach the joint from the axle.
- Inspect the inner boot. Replace it if torn or leaking grease.
- Thoroughly clean the axle shaft ends and CV joint housing to remove debris. Apply grease.
- Install the new CV joint assembly on the axle shaft per the manufacturer instructions.
- Replace the CV boot and secure the new clamps. Reinstall all removed parts and lower the vehicle.
Fixing Brake Grinding When Accelerating
For grinding noises only occurring when braking, focus on the following repairs to resolve the brake issues:
Worn Brake Pads
Inspect the thickness of the brake pads. If almost worn down to the metal backing plate, immediate replacement is needed. Follow these steps:
- Jack up the corner of the car and remove the wheel.
- Remove the two bolts securing the caliper. Hang it up or rest on a block.
- Slide out the worn brake pads. Insert new ones and secure the caliper.
- Reinstall the wheel and lower the car.
New brake pads cost around $25-$60 per axle for most vehicles.
Damaged Brake Rotors
If the rotors have deep grooves, thickness variation, or heat damage, replacement is required:
- With the wheel and caliper removed, unscrew the rotor from the hub.
- Clean away any grease or debris from hub contact area.
- Install the new rotor and secure with screws. Reinstall the brake caliper and pads.
New OEM rotors range from $50-$150 each.
Flush Brake Fluid and Clean Components
Moisture-contaminated brake fluid and brake component gunk can also cause grinding. Have your brake fluid flushed and the calipers, rotors, and pads cleaned to restore smooth operation.
When to Take Your Car to a Mechanic
While many grinding noise causes can be addressed with DIY repairs, consider having a professional mechanic diagnose and/or complete the repair if:
- You are unable to determine the exact cause of the grinding sounds. A mechanic can isolate the issue through diagnostic testing.
- The recommended fix requires auto repair knowledge beyond your skill level. For complex repairs like CV joints, wheel bearings, or brake boosters, improper work can make the issue worse.
- Brake grinding is coupled with other symptoms like pulsation through the pedal, fluid leaks, warning lights, or odd brake pedal feel. This indicates a more involved brake repair.
- The grinding occurs in multiple wheels simultaneously. It’s often cheaper to have a shop address multiple bad wheel bearings or CV joints at once rather than doing it one by one yourself.
Seeking help from a certified mechanic or repair shop can give you peace of mind from their expertise and warranty on completed repairs. But expect to pay more in labor costs compared to DIY repairs.
Preventing Future Grinding Noises When Accelerating
Proactive maintenance helps minimize the chances of grinding noises from worn wheel bearings, CV joints, and brakes in your car:
- Inspect components – Regularly check simple things like tire treads, brake pads, visible hardware. Look for early damage or leaks from seals and boots.
- Address minor problems early – Nipping issues in the bud before they catastrophically fail saves money and prevents breakdowns.
- Follow maintenance schedules – Stick to the recommended time or mileage intervals for brake fluid flushes, tire rotations, etc.
- Use high quality parts – Don’t cut corners on cheap components that fail prematurely when repairs are needed.
With proper inspection and care, you can add thousands of miles to your car’s lifespan and avoid worrisome grinding noises when accelerating.
Specifications Comparison Table
|Grinding when turning or accelerating. Loudest near the bearing.
|Remove wheel and brake parts. Press out old bearing, install new sealed bearing.
|$150-$300 per bearing
|Clicking/grinding, especially when turning. Worsens over time.
|Remove axle shaft. Detach joint, install new and replace boot.
|$350-$550 per joint
|Grinding only when braking. May occur with other issues.
|Replace pads and rotors. Flush fluid, clean components.
|$25-$150 per axle
Pros and Cons of DIY vs Mechanic Repairs
DIY Repair Pros
- Less expensive than paying a mechanic’s labor rates
- Learn new mechanical skills by tackling repairs yourself
- Convenience of working on your own schedule
DIY Repair Cons
- Repairs require mechanical skill, specialty tools, and auto know-how
- Trial and error can result in mistakes, worse damage if done improperly
- Physically demanding work with risk of injury
Mechanic Repair Pros
- Expertise to properly diagnose issues and complete complex repairs
- Efficiency from professional equipment and workflow
- Peace of mind from warranty on their work
Mechanic Repair Cons
- Added cost of paying for labor at shop rates
- Inconvenience of going to the shop and being without your vehicle
- Risk of dishonest mechanics overcharging for unnecessary work
Hearing grinding noises from your car when accelerating likely signals problems with the wheel bearings, CV joints, or brakes. Thoroughly inspecting the tires, hardware, and test driving the car can help pinpoint the cause.
Many grinding noise issues like worn brake pads and contaminated rotors can be repaired oneself with mechanical skill. But extensive repairs like replacing damaged wheel bearings or CV joints often require professional technician expertise, especially when needing to be completed on multiple wheels.
While grinding noises are annoying and worrisome, catching the underlying problems early is critical to avoiding breakdowns or accidents. With a robust maintenance routine and willingness to invest in quality repairs when needed, you can get your car running smooth and quiet again.