BMW Brake Fluid Service

BMW Brake Fluid Service

Brake fluid, it’s the lifeblood of your vehicles stopping system. However, many people forget that this often ignored maintenance item needs regular replacement. Many newer vehicles like this 2007 e90 335i come with a reminder light that lets you know when its time for a BMW Brake Fluid Service. For those of you without a warning lamp, you may be wondering when, as well as the reason for replacing your fluid. In order to better explain why we flush brake fluid, we will first have to discuss a little about some of the properties of hydraulic brake fluid.

2007 BMW e90 335i Brake hydraulic fluid service light maintenance reminder flush exterior headlights exterior silver bumper

Brake fluid is the hydraulic medium used to apply force transfer or amplify force to the brakes. Most Brake fluids (DOT 3, 4, and 5.1) are Glycol-ether based and are therefore hygroscopic, which means they absorb moisture from the atmosphere under normal humidity levels. After a service life of 2 years, the fluid has taken all the heating, cooling, and moisture it can handle. Any longer than this, the moisture starts to react with the steel in the braking system and corrosion starts to build up in the system. This corrosion can cause seals to fail, lines to rupture for the inside out, and even hydraulic components like the calipers to seize and fail. Also with major manufacturers moving to ABS and advanced traction control systems, the cost can be astronomical if one of the pumps, valve blocks, or other components fail. As you can see the cost of regular replacement of the brake fluid, is minimal in comparison to the cost of even just one of the brake system components.

2007 BMW e90 335i Brake hydraulic fluid service light maintenance reminder flush reservoir dirty old level sensor DOT 4 master cylinder

So remember, two years or sooner if you want to save expensive repairs!

For a Brake Flush, we hook up a special pressurizing system to push the old fluid out. A suction tube is hooked up to each of the caliper bleeder screws. The screws are then cracked starting with the rear right. As the Fluid flows through the clear tubing, we wait till the fluid appears clean and then we activate the DSC or ABS pump, and bleed again. We then work to left rear, front right and lastly front left. Once all the fluid comes out a light amber color, we know the fluid is going to be good for another 2 years.

On this car our customer decided to go with the upgraded BG Super DOT 4 Brake Fluid. Not only do they get the superior protection offered by BG products, but because this customer’s vehicle is under 75000 miles he also gets a life time warranty that covers up to $2000 worth of repairs on the brake system.

2007 BMW e90 335i Brake hydraulic fluid service maintenance reminder flush  dirty old super DOT 4 Pressure bleeder bleeding master cylinder hygroscopic new BG dry wet boling point

If you think its time to have your brake fluid flushed or are having problems with your brakes don’t hesitate to call us up at (630) 305-3054, or contact us through email at We’re conveniently located in the Naperville/Plainfield area of the Chicago Metropolitan suburbs.

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