Hydraulic hoses and pipes - inspection and renewal

Braking system / Hydraulic hoses and pipes - inspection and renewal

Flexible hoses
1 Periodically, all brake pipes, pipe connections and unions should be completely and carefully examined.

2 First examine for signs of leakage where the pipe unions occur. Then examine the flexible hoses for signs of chafing and fraying and, of course, leakage. This is only a preliminary part of the flexible hose inspection, as exterior condition does not necessarily indicate the interior condition, which will be considered later.

3 Flexible hoses are always mounted at both ends in a rigid bracket attached to the body or a sub-assembly. To remove them, it is necessary first of all to unscrew the pipe unions of the rigid pipes which go into them.

The hose ends can then be unclipped from the brackets. The mounting brackets, particularly on the body frame, are not very heavy gauge and care must be taken not to wrench them off (photo).

11.3 Front hydraulic hose bracket

4 With the flexible hose removed, examine the internal bore. If it is blown through first, it should be possible to see through it. Any specks of rubber which come out, or signs of restriction in the bore, mean that the inner lining is breaking up and the pipe must be renewed.

5 When refitting the flexible hoses check they cannot be under tension, or rub, when the wheels are at the full range of suspension or steering movement.

6 Bleed the system (see Section 12) on completion.

Rigid pipes
7 Inspect the condition of the braking system rigid pipelines at frequent intervals. They must be cleaned off and examined for any signs of dents (or other percussive damage) and rust and corrosion. Rust and corrosion should be scraped off and, if the depth of pitting in the pipes is significant, they will need renewal.

This is particularly likely in those areas underneath the car body and along the rear axle where the pipes are exposed to the full force of road and weather conditions.

8 Rigid pipe removal is usually straightforward.

The unions at each end are undone, the pipe and union pulled out, and the centre sections of the pipe removed from the body clips where necessary. Underneath the car, exposed unions can sometimes be very tight.

As one can use only an open-ended spanner and the unions are not large, burring of the flats is not uncommon when attempting to undo them. For this reason, a self-locking grip wrench (Mole) is often the only way to remove a stubborn union.

9 Rigid pipes which need renewal can usually be purchased at any garage where they have the pipe, unions and special tools to make them up. All they need to know is the total length of the pipe, the type of flare used at each end with the union, and the length and thread of the union. Fiat is metric, remember.

10 Fitting your new pipes is a straightforward reversal of the removal procedure. If the rigid pipes have been made up, it is best to get all the sets bends in them before trying to fit them. Also, if there are any acute bends ask your supplier to put these in for you on a tube bender. Otherwise, you may kink the pipe and thereby restrict the bore area and fluid flow.

11 Bleed the system (see Section 12) on completion.

Fig. 8.11 Typical hydraulic hose connection (Sec 11)