Caution: Replacement of air conditioning system hoses must be performed by a service center specialist equipped with special equipment for safe depressurization of the system. Until the system is sealed, it is not allowed to remove hoses or system components.
General information
1. The high temperature in the engine compartment can cause aging of rubber and plastic hoses used in engine systems, auxiliary equipment and the control system for the release of toxic substances into the atmosphere. Periodic inspections should be carried out to identify possible cracks, loosening of the clamps, hardening of the material and leaks.
2. Specific information on the air conditioning system is provided in section 14.
3. Some, but not all, hoses are secured to the fittings with clamps. Where clamps are used, check that they are tight enough to prevent leakage. Where clamps are not used, check that the hose has not swollen and/or lost its elasticity where it fits onto the fitting.
Vacuum hoses
4. Vacuum hoses, especially Emission Control hoses, have a common color code or color stripes melted onto them. Different systems require hoses with different wall thicknesses, crush resistance, and heat resistance. When replacing a hose, make sure the new one is made of the same material as the old one.
5. Often the only effective way to check a hose is to remove it from the car. If you have removed more than two hoses, mark them so that they can be reinstalled correctly in their old location.
6. When checking the vacuum hoses, also check all the plastic tees. Make sure there are no cracks in the fittings and no damage to the hoses that are put on these fittings.
7. To detect air leaks, you can use a small piece of vacuum hose (internal diameter 6 mm) as a stethoscope. Bring one end of the hose to your ear and move the other end along the hoses and fittings, looking for a hissing sound, which characterizes air leaks.
Warning: When using a stethoscope from a vacuum hose, be careful not to touch moving engine parts such as drive belts, cooling fan, etc.
Fuel hoses
Caution: On fuel injected models, relieve pressure from the system before disconnecting the hoses (see Chapter 4).
8. Check all rubber hoses for signs of aging and cracking. Check especially for cracks where the hoses bend, such as where the hose connects to the fuel filter.
9. It is best to replace hoses with high-quality ones, usually marked with the word Fluroelastomer printed on the hose. Do not use non-reinforced vacuum hoses, clear plastic tubes or water hoses as fuel lines. Fuel injection models use special high-pressure fuel hoses. Use only appropriate hoses for replacement.
10. Fuel lines are usually equipped with spring-type clamps. Over time, these clamps lose their elasticity. When replacing hoses, replace the clamps with new ones.
Turbocharger Hoses
11. On turbocharged models, the air intake and oil supply hoses should be checked periodically.
12. Check for cracks or leaks in the air intake hoses. Replace damaged hoses.
13. Check the oil supply hoses for leaks and replace them if necessary.
Metal pipelines
14. Metal fuel lines are often installed between the fuel pump and the fuel injection unit or carburetor. Carefully inspect the line for dents, kinks, or cracks.
15. If it is necessary to replace a section of metal tubing, only seamless steel tubing may be used, since copper and aluminum tubing do not provide sufficient strength to withstand the vibrations that accompany normal engine operation.
16. Check the metal brake system pipes where they attach to the master cylinder and brake equalizer (if used) for cracks and tightness of the connection. Traces of brake fluid leakage are a signal for immediate inspection of the entire brake system.