Defective master cylinder? That must be taken into account!

Is the master brake cylinder defective? We have important information about the symptoms, the repair/replacement process and, of course, the costs that may be incurred. Yes, before that some information about the master brake cylinder (master brake booster). It is an important part of the braking system in a car Brake booster, the pressure means brake fluid about the Brake Lines to the individual wheel brakes. Due to age-related wear or other reasons, it can happen that the master brake cylinder leaks and no longer works properly.

possible symptoms

• The brake responds differently than usual.
• The brake pedal "does not come back".
• The brake pedal travel changes (depressing the brake pedal due to insufficient resistance, later onset of the braking effect).
• Entry in error memory (Brake pressure sensor value too low / implausible).
• The braking distance becomes longer.

Can you continue driving with a defective master brake cylinder?

A leaking or defective master brake cylinder is a significant risk for you and other road users. If a defective master brake cylinder is suspected, the vehicle should under no circumstances be moved. Instead, it should promptly convert to a Workshop to be towed. Further use can also cause consequential damage to the brake booster or the ABS system which can lead to a significant increase in repair costs.

Repair or installation of a new part?

In most cases, it makes sense to completely replace the master brake cylinder in the event of a defect to exchange, at oldtimers or youngtimers on the other hand, it can be worthwhile to have one Repair with a repair kit to be carried out or to be carried out. In this context, used parts are usually a bad alternative, since the age and condition of the master brake cylinder are often difficult to identify. Is for the desired vehicle BKV no longer available, then a used part is still conceivable. Only the origin and condition must be traceable. The procedure for changing the master brake cylinder can vary depending on the vehicle model.

The main brake cylinder is usually located in the engine compartment near the bulkhead. Above it is the reservoir and expansion tank for the brake fluid mounted, which can be recognized by a yellow cover. After Disconnect the battery the brake fluid is first sucked out for disassembly. After that, the Brake lines from the master cylinder removed. This is followed by the dismantling of the ABS control unit and the expansion tank for the brake fluid. After installing the new master brake cylinder, a test drive follows to ensure that the new system works perfectly and brakes reliably. Since the brake system has to be emptied and bled during repairs, the brake fluid also becomes direct completely renewed. The old brake fluid can not reused .

Repair costs when changing the master brake cylinder!

The cost of replacing the master brake cylinder can vary greatly depending on the vehicle. The material costs range between 15 and 750 euros and depend on the vehicle and spare parts manufacturer. Well-known manufacturers of such spare parts include, for example, ABE, NK, TRW and ATE. The new brake fluid increases the material costs by another 20 to 100 euros. The comparatively high costs are due to the fact that spare parts are only available on the "free market" for a few vehicle models. That is why it is often necessary to resort to more expensive original parts from the original equipment manufacturer. However, an associated advantage is that a high safety standard is guaranteed. The time required to change the master brake cylinder is usually two to four hours and depends on how many parts have to be dismantled for the change. At an hourly rate of 100 euros, this results in labor costs of between 200 and 400 euros. Changing a master brake cylinder therefore costs a total of between 230 and 1.250 euros.

How the master brake cylinder works

The master cylinder serves the rapid build-up and reduction of pressure in the braking system during braking and after braking. The pressure transmission within the hydraulic brake system takes place with the help of the brake fluid and is supported by the brake booster. Since about 1990 in vehicles so-called Tandem master cylinder installed. These increase safety by increasing the braking power over two separate brake circuits transfer. Such a braking system is mandatory today because even if there are problems in one of the two brake circuits, the brakes will still function properly.

The following note is essential: For safety reasons, tuningblog recommends all repair, inspection and maintenance work exclusively to be carried out in a specialist workshop! Although our information is summarized to the best of our knowledge and belief, we cannot assume any liability for the content. All information is therefore "without guarantee".

Of course, that wasn't the end of it!

In this tuningblog category there are guides and instructions for common defects/repairs on the vehicle and for installing accessories/tuning parts. Our articles explain in a simple way common defects and the corresponding repairs, as well as explaining how the first signs of a defect become noticeable. In most cases, we also have initial clues to the repair instructions in our repair instructions approximate The costs of the pending repair are listed. The goal of our subcategory “Auto Repair Guide“ is to create a head start in knowledge for the next visit to the workshop with initial tips. This may save you from tedious troubleshooting and small things can perhaps be done directly on your own. The same applies, of course, to the installation of accessories/tuning parts. Here, too, we would like to help with the implementation with instructions and tips. There are many other posts on this as well. Below is an excerpt of the last and HERE there are all previous instructions:

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