Car MOT Manual 2012 onwards
Brakes - 3.6 All Braking Systems
Repairs to the pressure lines of hydraulic brake systems are unacceptable unless suitable connectors are used. Compression joints of a type using separate ferrules are not suitable.
1. Check for leaks in any part of the braking system with and without the brakes being applied.
2. Check all components for security, condition and operation.
Note: It is not always possible to determine the presence and effectiveness of certain types of locking devices e.g. locking fluid or nyloc nuts.
3. Check all braking system components for any inappropriate repair or modification.
2. A braking system component:
a. insecurely mounted
b. excessively weakened by corrosion
c. damaged to the extent that its function is impaired
d. retaining or locking device missing or insecure.
3. A braking system component inappropriately repaired or modified.
Brakes - 3.6 Brake Pipes and Flexible Hoses
A missing brake pipe clip is not necessarily a Reason for Rejection provided the brake pipe remains adequately supported.
To correctly assess the condition of corroded metal brake pipes, surface dirt might have to be removed. This might require light scraping with the Corrosion Assessment Tool spade end. Care must be taken not to damage any protective coating.
Chafing, corrosion or damage to a rigid brake pipe so that its wall thickness is reduced by 1/3 e.g. approximately 0.25 mm for typical hydraulic brake pipe is a reason for rejection.
A hose should be rejected for cracking or chafing only if it is severe enough to expose the reinforcement.
Certain alloy components may have a white surface deposit which is not to be regarded as excessive corrosion.
1. Check that rigid brake pipes are securely held and not free to vibrate.
2. Check all accessible rigid brake pipes for:
a. fouling by a moving part
c. chafing, corrosion and damage.
3. Examine flexible hoses for signs of weakness under pressure with brake fully applied.
4. Examine all flexible hoses for:
a. room to move as necessary without fouling any part of vehicle
c. stretching or twisting
d. chafing, damage or deterioration
e. condition of ferrules
f. exposure to excessive heat.
2. A rigid brake pipe:
a. fouled by moving parts
c. excessively chafed, corroded or damaged.
3. A flexible hose bulging under pressure.
4. A flexible hose:
a. has insufficient room to move, resulting in fouling
c. stretched or twisted
d. excessively chafed, damaged or deteriorated
e. brake hose ferrules excessiv
Brakes - 3.6 Servos and Master Cylinders
1. Check servos for:
b. condition of vacuum pipe
2. Where an adjustment indicating rod is provided, check if brake adjustment is necessary.
3. Examine the condition of chassis or body structure and panelling around the master cylinder or combined master cylinder / servo mounting.
a. missing when fitted as standard
b. vacuum pipe deteriorated, kinked, split, collapsed or excessively chafed
2. Adjustment indicating rod shows brake adjustment is necessary.
3. Deliberate modification which significantly reduces the original strength, excessive corrosion, severe distortion, a fracture or an inadequate repair of a load bearing member or its supporting structure or supporting panelling within 30cm of the master cylinder/servo mounting, that is, within a prescribed area, see Appendix C.
Brakes - 3.6 Reservoirs Air/Vacuum including accumulators, pressure and vacuum vessels
1. Check reservoir mountings and securing straps:
a. are free from cracks, fractures and excessive corrosion
b. do not chafe the reservoir or other fittings.
2. Check that the reservoir capacity is not unduly reduced by deformation.
a. cracked, fractured or excessively corroded
b. chafing reservoir or other fittings.
2. A significant reduction in reservoir capacity as a result of deformation.
Brakes - 3.6 Valves
1. Check for excessive discharge of oil from valves.
2. Check that a load sensing valve is present and connected, if it is a standard item.
3. Check the condition and operation of the load sensing valve where fitted, including any operating linkage.
2. Evidence that a load sensing valve has been removed or disconnected from a vehicle where it is known to have been fitted as standard.
3. A load sensing valve or its operating linkage obviously:
• seized or inoperative
• defective so that its function is impaired, or
• incorrectly adjusted.
Brakes - 3.6 Pumps and Compressors
1. Check the condition of the pump or compressor drive system.
Brakes - 3.6 Hydraulic Systems
A brake fluid warning lamp may be a combined lamp for other aspects, such as worn brake pads or parking brake applied.
1. Check fluid reservoirs for:
a. presence of cap
b. fluid level.
2. Check that the brake fluid warning lamp is not illuminated or defective.
a. cap missing
b. level below the minimum indication when this is shown.
2. A brake fluid warning lamp is illuminated or inoperative.
Brakes - 3.6 Air Systems
1. Check each brake cylinder/actuator for travel of operating pistons/diaphragms and mechanisms.
2. Check the presence and condition of dust covers on brake actuators.
b. has excessive travel of the operating mechanism indicating need for adjustment.
2. A brake actuator dust cover missing, insecure or damaged to the extent that it no longer prevents the ingress of dirt etc.
Brakes - 3.6 Additional Braking Devices
1. Examine the device, its contacts and other components for condition and security.
2. Check for adequate clearance between the device and other components.
3. Check for presence and condition of heat shields if required.
4. Check for signs of overheating of a component or its surroundings.
5. Check for condition, position and security of electrical wiring and switchgear.
6. Check for exhaust gas or oil leaks.
2. Inadequate clearance between the device and other components.
3. A heat shield missing or damaged.
4. Overheating of a component or its surroundings.
5. Wiring in poor condition, badly positioned or not secure.
6. Exhaust gas or oil leaking from the device.
Brakes - 3.6 Electronic Braking Systems Class 5 only
1. On vehicles fitted with an electronic braking system, check that a warning device:
a. is fitted
b. is operative
c. does not indicate a fault
a. is missing
c. indicates a fault