2020-2024 Mercedes-Benz GLE350 Brake Noise: Squeal, Grinding and Pulsation Causes

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most brake noise on a 2020-2024 Mercedes-Benz GLE350 comes from one of three things: pads that are worn, glazed or missing their shims and grease (squeal), pads worn to the backing plate or grit trapped in the caliper (grinding), and rotor thickness variation or runout (pulsation you feel in the pedal and steering wheel). Each has a distinct sound or feel, and each points to a different part. This guide walks through how to tell them apart and what to replace.

How the GLE350 Brake System Works

The V167 GLE350 uses disc brakes at all four corners, a hydraulic system filled with brake fluid, and an electric parking brake instead of a hand lever or foot pedal. The instrument cluster watches pad wear electronically: when the pads reach their wear limit it shows the message Check Brake Pads See Operator's Manual. Mercedes-Benz warns in the 2020 GLE Operator's Manual that at this point braking power may be restricted and the brake system should be checked immediately.

Because the GLE is a heavy SUV, its brakes turn a lot of motion into heat on every stop. That heat, plus road salt, moisture and brake dust, is behind nearly every noise complaint. Knowing which noise you have is the fastest way to buy the right part the first time.

Noise Symptoms and What They Usually Mean

Squeal

Squeal is vibration. The pad and rotor vibrate against each other at a frequency you can hear, and the caliper and knuckle act like a speaker. Brembo notes that squeal after a brake job is often not a defect in the new part at all, but the result of worn or neglected components around it: corroded caliper slides, tired anti-rattle springs, reused shims, or a dirty hub face. Pads that have been overheated can also glaze, leaving a hard, shiny surface that squeals and grips poorly.

Grinding

True grinding means metal is touching metal. If the pad warning has been ignored, the friction material can wear through and the steel backing plate cuts into the rotor. At that point the rotor is scored and needs replacing along with the pads. The GLE Operator's Manual also cautions that sand, mud and water can enter the brakes during off-road driving and increase wear, and that if you hear scraping noises afterward you should have the brake system checked.

Pulsation

A pulse in the pedal or a shake in the steering wheel during braking is almost never a truly "warped" rotor. It is thickness variation: the two faces of the rotor are no longer parallel, so the pads push the caliper pistons in and out as the rotor turns, and you feel that through the pedal. General Motors brake diagnosis service information describes measuring rotor thickness at several points with a micrometer and checking lateral runout with a dial indicator, then replacing rotors that fall outside specification. Brembo's published limits are rotor runout of no more than 0.10 mm and hub runout under 0.050 mm; excess runout at the hub will ruin even brand-new rotors.

Causes Specific to How GLEs Are Driven

• Riding the brakes. The Operator's Manual warns that continuously pressing the brake pedal wears out the linings and advises shifting to a lower gear to use engine braking. Constant light braking also overheats pads and lays uneven deposits on rotors, a common cause of pulsation.
• Road salt. Mercedes-Benz notes that salt build-up on discs and pads can considerably increase braking distance or cause braking on only one side. Its advice is to brake occasionally when traffic allows and to press the pedal carefully at the end and start of each trip. Salt crust also makes noise.
• Washing and parking wet. The manual recommends driving a few minutes after cleaning so the discs and pads warm up and dry before the vehicle is parked. Parking wet builds rust that scrapes and can leave pad imprints on the rotor face.
• Harsh wheel cleaners. Acidic wheel cleaners used to remove brake dust can damage wheel bolts and brake components, per the manual.
• Careless wheel service. The manual cautions against applying force to the brake discs when changing a wheel, since it can affect braking comfort. Tighten wheel bolts in a cross pattern to the value in the Operator's Manual.

The Fix and Which Parts to Buy

Start with an inspection of all four corners: pad thickness, rotor surface, caliper slides and boots, and the hub face. Then match the fix to the symptom.

• Squeal with good pad thickness: clean and lubricate the caliper contact points with a brake-specific grease, fit new shims (Brembo says never reuse old ones), and replace tired abutment springs. If the pads are glazed, replace them.
• Pad warning or thin pads: replace pads on both sides of the axle. For the rear axle, our 2020-2024 GLE350 rear ceramic brake pads by Bosch are a low-dust, quiet option. Browse all ceramic brake pads for other positions.
• Grinding or pulsation: replace the rotors together with the pads. Brembo recommends always fitting new pads when discs are changed so the new surfaces bed in together. See our brake rotors and brake pads.
• Sticking caliper or torn boot: a caliper that drags will overheat one rotor and make noise. Replace it from our brake calipers collection.

What to Replace at the Same Time

• Pad wear sensor. Once a Mercedes-Benz wear sensor has triggered it should be replaced with the pads; reusing a tripped sensor will keep the warning on.
• Hardware. Shims, clips and slide pin boots are cheap compared with a comeback for noise. Our brake hardware kits cover this.
• Brake fluid. Brake fluid absorbs moisture from the air, which lowers its boiling point and can cause vapor pockets under hard braking. Mercedes-Benz calls for fluid approved to MB-Approval 331.0, renewed at the interval in your maintenance booklet. A brake job is a good time to flush it.

How Hard Is the Job?

Front pads and rotors on a GLE350 are a moderate driveway job for someone with a torque wrench, jack stands and a clean, flat surface. The rear axle adds one step: the electric parking brake works at the rear brakes, so it has to be released and put into its service position before the rear pistons can be pushed back. Most shops do this with a scan tool; forcing the pistons can damage the parking brake actuator.

After the job, bed the brakes in. Mercedes-Benz notes that new pads and discs only reach their best braking effect after several hundred kilometers of driving, and Brembo recommends roughly 300 km of gentle braking without abrupt stops. Light squeal in the first few days that fades is normal; squeal that stays points back to hardware or lubrication.

Frequently Asked Questions

Why do my GLE350 brakes squeal after new pads?

The most common reasons are reused shims, dry or missing grease on the pad ears and caliper bracket, corroded slides, or pads that have not bedded in yet. Brembo points to surrounding worn components more often than to the new pad itself.

Is it safe to drive with the Check Brake Pads message on?

Mercedes-Benz says braking power may be restricted when the pads reach their wear limit and advises driving carefully and having the brakes checked immediately. Do not wait until you hear grinding.

Can I resurface the rotors instead of replacing them?

Only if they stay above the minimum thickness marked on the rotor after machining and the hub runout is within limits. On a heavy SUV, thin machined rotors overheat quickly, so replacement is usually the better value.

Why do my brakes grind in the morning and then stop?

That is surface rust from overnight moisture or a recent wash. It normally wipes off in a few stops. If it does not, or it leaves a pad-shaped mark on the rotor, inspect the pads and rotors.

Are there any brake recalls on the 2020 GLE350?

NHTSA's recall list for the 2020 GLE350 does not include a brake hardware recall. Always run your own VIN on nhtsa.gov, because recall coverage depends on the individual vehicle.

Do I need to replace pads on both sides?

Yes. Pads are always replaced as an axle set so both sides brake evenly. Replacing one side can make the SUV pull and wear the new pads unevenly.

Sources

1. Mercedes-Benz 2020 GLE SUV Operator's Manual - pad wear message, break-in distance, salt and wash guidance, off-road scraping, brake fluid MB-Approval 331.0, electric parking brake
2. Brembo - Noises and vibrations - causes of squeal, disc and hub runout limits, never reuse shims, bedding-in distance
3. General Motors brake noise, judder and pedal feel diagnosis (NHTSA TSB file) - measuring thickness variation and lateral runout
4. NHTSA recalls for the 2020 Mercedes-Benz GLE350 - recall list with no brake hardware campaign