Check Brake Fluid
Braking systems in cars and trucks rely on brake fluid for their operation. Pushing the brake pedal moves this fluid through the brake lines and hoses, with additional force coming from the brake booster. The fluid moves into the brake calipers, pushing the brake pads together to grip the brake discs. If there is too little fluid in the system, the pedal will move a long way before the pads start to bite, and if the fluid is really low, they might not grip the discs at all.
To avoid these problems brake fluid should be checked at regular intervals, ideally on a weekly basis. A good time to do it would be when topping up the screen wash bottle under the hood.
Brake fluid is usually held in a plastic or metal reservoir mounted above the master cylinder. In most vehicles this can be found under the hood and in front of the driver. (There are some goodpictureson the “Dummies” website.) Usually it’s possible to see the fluid through the walls of a plastic reservoir and compare it with the “Full” indicator on the side. If the fluid is more than around a quarter inch below this level, it should probably be topped up. Likewise, with a metal reservoir, consider topping up if the level is more than a quarter inch below the top.
There is however one exception: If the brakes pads are due for replacement, it would be prudent to attend to them first. The reason is that new pads will push the pistons back into the brake calipers, raising the level of fluid in the reservoir. But if the pads are reasonably new and the fluid level is low, it should be topped up.
When checking the fluid level also take note of its clarity. While brake fluid comes in various colors and can also be clear, there should be no cloudiness. Murky fluid might have absorbed water, which can cause two serious problems.
• Corrosion—rust—which will gradually damage seals in the brake system, eventually leading to leaks and low fluid levels.
• Water boils at around 212°F (100°C). Braking systems can quite easily generate these temperatures, leading to water vapor in the brake lines. Unlike brake fluid, vapor is compressible under pressure, so when there’s vapor in the lines, braking effort is lost.
Auto repair stores sell kits to test for water contamination, but a better option is to take the vehicle to the dealership or a repair shop for an expert opinion. To avoid water contamination, most vehicle manufacturers recommend changing the fluid every two or three years.
As brake fluid manufacturer Advance Petrochemicals points out, there are several differentgrades of brake fluid. These are identified as DOT 3, DOT 4, DOT 5 and DOT 5.1. Except for DOT 5, these are all glycol-based fluids, the main difference being their boiling points. DOT 5 brake fluid is different in that it’s silicone-based. Only use the grade already in your brake system. Different grades should never be mixed. Usually there will be an indicator on the reservoir to show what grade of fluid should be used.
To top up the fluid level, start by purchasing the correct fluid, then follow this procedure:
• Locate the reservoir and cover the surrounding areas with rags to catch any drips or spills.
• Open up the reservoir and slowly pour in additional fluid. Take care not to add any air bubbles, for instance, by shaking the bottle.
• When the fluid reaches the Full mark, close up the reservoir.
• Remove and dispose of the rags used to catch drips.
The braking system is the most important part of a motor vehicle, so if there is any concern about the way the brakes are working, take it to the dealer or a qualified mechanic to be checked out. In particular, should any brake warning light come on, or any softness of the brake pedal become apparent, have the system inspected as soon as possible.
