One problem you may have with your car's brake pedal is that, when you step on it, it sink in little by little until the end of its journey. This can happen after change the pads, for example, but there are many other probable causes that it is advisable to see as soon as possible.
Brakes are one important part of the vehicle and it is essential to keep them in good condition. So don't try to drive around with it before you have the problem completely fixed. You would not be the first or the last to trust yourself and end up having an accident.
brake fluid leak
A common cause may be brake fluid leaking from a line. To check if this is the case, we recommend that you take a look at the article: How to know if the vehicle is leaking brake fluid. There are some tricks that can make your task much easier.
Normally the loss is through a brake hose. If so, you must replace the damaged hose and it is also advisable check all hoses to avoid problems in the future. Once replaced, you must bleed the brake circuit to remove the air inside it.
Air in the brake circuit
Another cause is that if you have been touching the brake system, has been poorly purged al change the brake fluid. That is, it still has air inside. In this case, in addition to the pedal sinking, the most normal thing is that you notice it spongy when you step on it.
To fix it, you have to purge it again to correct this defect. There are several methods, but below we detail the use of a hand vacuum pump. It is an easy system, relatively fast and for which the help of another person is not necessary. The steps to follow are:
- If you don't have a vacuum pump, you can get one for very little money. Amazon's are fine and they are reasonably priced, although you have a huge repertoire of models to choose from.
- We recommend that you remove all the brake fluid from the master cylinder with the pump. Once done, introduce new liquid.
- Access to brake fluid discharge valves. You have to do it the way crusade: first the back on one side, then the front on the other, go back to the back you have left and end up going back to the other front.
- Use the bomb to extract the brake fluid with bubbles of each of the brakes. To do this, first adjust the pump hose and then open the valve. Normally it works is done with a wrench. A common mistake is to use the pump hoses or nozzles alone. Normally, this is not enough. Better put a zip tie or Teflon to secure the hose each time you do it.
- Every time you bleed on each wheel, make sure the master cylinder cup is not leaking too much fluid. Fill if necessary by pouring liquid carefully without splashing or foaming.
Faulty brake pump
If our car does not have any of these problems or, even after having bled the brakes and replaced the hoses, the brake pedal continues to sink, the problem may be in the brake pump.
The master cylinder, also called master cylinderIt is located in the engine compartment. Its main function is to transform the force you exert on the brake pedal into hydraulic pressure in the brake circuit. In this case, you must replace the brake pump and, once the new one is in place, properly bleed the circuit.
El price of a brake pump or master cylinder is not usually high. You can find them for prices of between 30 and 50 euros easily if your model is not premium. The replacement process can vary a lot from one model to another, because it depends on where it is in the engine compartment.
On most cars, the tools you'll need are a appropriate size wrench and a pipe wrench (It is better if it is magnetic so that the screws do not fall into the vain. To remove the master cylinder, the process is usually:
- cover with paper or rags the area to avoid staining anything with brake fluid, because it is corrosive.
- remove the electrical connector and remove it so it doesn't bother
- remove the screws that fix it to its place
- remove the lines that connect it to the hydraulic brake circuit.
To fit a new master cylinder always must be purged before installation. Many models come with their own bleed kit. If you want to facilitate the process, it is better that you opt for one that includes it. In the following video you can see how this operation is performed and the previous ones mentioned in this article.
Once the operation is done, the problem should be solved, holding the brake pedal steady. As for the time it takes to perform these operations, brake bleeding can take about half an hour. In the case of the hoses, they can also be changed in a short time, about an hour for the front ones.
If it becomes necessary to replace the master cylinder, the time varies greatly depending on the model in question, although it may take approximately an hour and a half.
Remember Your brake problem doesn't have to be just one problem.. It is common that there are several causes behind a pedal that sinks excessively. Therefore, it is better that you do all the checks until the problem disappears, it is not going to be a combination of various faults.
