Current time is 2016-12-09 09:24:16.
Ready Set STOP!
Any chain is only as strong as its weakest link and, naturally, the same goes for the various systems in our cars. Luckily, when it comes to brakes, the Volvo system is a very good one right out of the box. Of course many miles down the road the brakes may not be up to par unless the system has had routine inspections and proper care.
The flexible brake hoses are one part of the brake system that can be subject to damage and deterioration. These hydraulic hoses connect the brake pipes at the front wheels and rear axle, flexing with the suspension movement. The front hoses are easy to see by turning the wheel to the side you want to inspect. In the back, they can be seen when the car is on a lift or safely supported on jack stands. They are attached to the axle and to the regulating valve that controls the front/rear brake pressure bias.
Brake hoses can be damaged by chafing, from being stretched out or bent hard. Age and environmental stress can cause the external rubber covering to crack as well. Look carefully around the fittings for signs of this common problem. Rubber brake hoses can also suffer from internal deterioration. While somewhat less common, this can result in swelling or bulges. It can cause the affected hose to act as a one way valve — allowing fluid to pass into the caliper, but not allowing pressure relief once you take your foot off the pedal. This will cause the brake to bind, resulting in a warped rotor, accelerated pad wear, and a host of problems that are well worth avoiding. Any sign of swelling or bulging is an indication that the old brake hoses have become unsafe.
Any time brake hoses have been damaged, replacement is in order. Popular for use on racecars, Teflon lined stainless steel braided brake hoses, available for most Volvo models, are a good choice in terms of the eternal quest for a firm pedal (in addition to looking really sharp). All brake hoses require regular inspection for chafing or contact with sharp objects that could cause wear.
Installing brake hoses is pretty straightforward for the experienced do-it-yourselfer. This is a good time to bleed the brake system and change the brake fluid. Volvo recommends: “Replace brake fluid every third year, or 45,000 miles = 75,000 km. Change brake fluid every year when the car has been driven under extremely hard conditions; mountain driving, etc...” (Volvo Service Manual, Section 1, Group 7). If your fluid is already fresh, you can prevent fluid from draining when replacing the lines by temporarily sealing the brake master cylinder cap vent hole. This will simplify the bleeding process considerably.
Be sure you have plenty of DOT4 brake fluid from a well-known manufacturer on hand for the job. Only clean, fresh, unused brake fluid must be used when topping up the system. Old brake fluid changes color, and ranges from yellow to dark brown when contaminated. Brake fluid is hygroscopic, which means even the best brake fluid will absorb moisture from the air and become contaminated. For this reason, it’s wise to purchase brake fluid in small containers. The mixing of different types of brake fluid is never recommended.
Keeping the fluid fresh will help you to prevent sticking caliper pistons, and many other problems that can plague older cars’ braking systems.
A can of brake cleaner will also come in handy, but be aware and use care, as this can be a hazardous substance if inhaled or absorbed through the skin.
Brake fluid, too, is caustic and will harm painted surfaces so wipe it off and clean painted surfaces and spills immediately. Rinse with water. Cleanliness is next to...well, next to good brakes, in this case. I can’t stress enough that the area must be completely clean and free from any particles, grease, and undercoating before you open the hydraulic system.
First of all, be sure that the bleeder screws on each caliper will turn freely, as you will need to use them. Use great care to avoid undue force that could break off any that have become seized. Old bleeders can be replaced with new ones if they seem rusty or have lost their caps; this may help to ensure easier brake bleeding in the future.
Actually changing the hoses requires the use of very few tools. I use PB B’laster penetrating oil to loosen any corrosion on the external threads of the fittings. Flare wrenches are most useful for this venture. Like a box wrench with an opening for the brake line, they offer more support than an open end wrench and prevent rounding off the flare fittings. Patient use of flare wrenches will persuade most fittings to yield to your will. If the old hoses are trashed, my favorite method is to cut the old hose off at the fitting, slip a deep 3/8” socket over it and turn it with my ratchet while holding the fitting it mates to with a flare wrench.
As for bleeding the brakes, I recommend using a pressure bleeder, although the old two-person “pump and hold” method can work if you’re careful not to push the pedal beyond its normal travel (which can cause damage to the master cylinder). Continue bleeding until the pedal is firm. A spongy feeling or sinking brake pedal is an indication that compressible air remains in the system.
Once you have installed your new brake hoses, you may congratulate yourself.
Great brakes are truly something to be proud of. As I’m fond of saying, it’s not good when your car won’t go, but it is far worse when it won’t stop