Acura Tech Tip: Brake Master Cylinder Leaking

Acura Tech Tip: Brake Master Cylinder Leaking

A cup seal in the master cylinder is sensitive to the type of brake fluid used in the brake system. If the brake fluid is replaced with anything other than Acura (or Honda) Genuine DOT 3 Brake Fluid, and the brakes are manually bled, the cup seal may twist in its retention groove and create a small leak.


Models

2005-2006 RL

Condition
A cup seal in the master cylinder is sensitive to the type of brake fluid used in the brake system. If the brake fluid is replaced with anything other than Acura (or Honda) Genuine DOT 3 Brake Fluid, and the brakes are manually bled, the cup seal may twist in its retention groove and create a small leak. The brake fluid can then leak into the brake booster, and the brake system indicator will eventually come on because the brake fluid level is low.

If the owner continues to drive the vehicle without refilling the brake fluid reservoir, they may notice the brake pedal feel slow or spongy. The drive should not rely on refilling the brake fluid reservoir to address the problem. A prolonged leak would eventually cause one of the two brake system hydraulic circuits to fail.

Correction
Install a master cylinder repair kit and, if needed, replace the brake booster. Vehicles that have already had the procedure performed at the dealer will have center-punch a completion mark above the ninth character of the engine compartment VIN.

You May Also Like

Axle Torque Procedures

Guessing the correct torque setting is a bad idea.

The physics of all threaded fasteners are the same. As the bolt and nut are turned, the spiral threads convert rotational force into a linear force that creates clamping loads. When a threaded fastener is tightened, it stretches. Since metal is elastic, even greater clamping loads are generated. The threads also generate friction that keeps the assembly together. This especially applies to wheel bearings and axle nuts.

Gen 1 Wheel Bearings

Removing and installing these bearings requires the correct tools and patience.

Tapered Wheel Bearings

Here’s what you should know as a technician when servicing tapered wheel bearings.

Understanding Passive Wheel Speed Sensor Operation

Passive types of wheel speed sensors are still used in many applications so understanding their operation is important.

Threadlocking Compounds For Vehicle Corners

To get the most out of these “liquid” tools, you first need to know how they work.

Other Posts

Please Take Our Brakes/Rotating Electrical Survey

By entering, you’ll have a chance to win a $100 gift card or one of 10 $25 gift cards!

Replacing Master Cylinders

The most common problems that occur in the master cylinder are wear in the piston bore and piston seal failure.

April’s ShopOwner Brings May Business Success

Read the new edition online now for solid business, technical and management information for your shop.

Read the March ShopOwner Digital Edition Now

Each issue is free to download and read, priceless in business value for your operation.