Caution! Replacement of air conditioner hoses should be left to the dealer or an automotive air conditioning specialist who is properly equipped to handle the system safely. Never remove air conditioner components or hoses until the refrigerant has been discharged from the system, which should also be done by the dealer or an automotive air conditioning specialist.
General information
1. High temperatures in the engine compartment can cause deterioration of rubber and plastic hoses used for engine, auxiliary and emission control systems. Periodic inspection should be performed for cracks, loose clamps, hardening of the material and leaks.
2. Specific information on cooling system hoses can be found in paragraph 11.
3. Some, but not all, hoses are secured to the fittings using clamps. Where clamps are used, ensure that they are tight, as insufficient tightening may result in a leak at the hose connection. Where clamps are not used, ensure that the hose has not expanded and/or hardened where it sits on the fitting, as this may result in a leak.
Vacuum hoses
4. Vacuum hoses, especially those used in emission control systems, are typically color-coded or have raised color stripes to identify them. Different systems require hoses with different wall thicknesses, crush resistance, and heat resistance. When replacing hoses, ensure that the new hoses are made of the same material.
(The text is taken from the specified website: www.ToyotaMAN.ru)
5. Often the only way to check a hose is to remove it completely from the vehicle. If you are removing multiple hoses, mark them and their fittings to ensure proper installation.
6. When checking vacuum hoses, be sure to check all plastic T-fittings (tees). Inspect the fittings for cracks, and check the holes at the ends of the hose for deformations, as such defects can cause leaks.
7. A small piece of vacuum hose can be used as a stethoscope to detect vacuum leaks (with an internal diameter of approximately 6 mm). Place one end of the hose to your ear and, using the other end as a feeler gauge, inspect the hoses and connections, listening for a "hissing sound" which is a sign of a "vacuum leak".
Caution: When examining the vacuum hose with a stethoscope (improvised or real) be very careful not to hit moving parts of the engine such as drive belts, cooling fan, etc.
Fuel hoses
Warning! Gasoline is highly flammable, so extra precautions should be taken when working with any part of the fuel system. Do not smoke or allow open flames or unshielded lights near the work area. Do not work in areas where there are appliances that use gasoline (for example, water heaters or clothes dryers). Since gasoline is a carcinogen, do not allow fuel to come into contact with exposed areas of the body; wear gloves that are resistant to gasoline. If fuel comes into contact with the skin, wash the affected area immediately with soap and water. Wipe up any spilled fuel immediately and do not store rags soaked in fuel in places where it may catch fire. The fuel system is under constant pressure, so be sure to relieve the fuel pressure in the system before disconnecting the fuel lines. Wear safety glasses when performing any work on the fuel system. Always keep a class B fire extinguisher on hand.
8. Check all rubber fuel lines for deterioration and chafing. Check especially for cracks in bend areas and immediately before fittings, such as where the hose connects to the fuel filter.
9. When replacing the fuel line, use a high-quality fuel line. Do not, under any circumstances, use a non-reinforced vacuum line, transparent plastic line, or water hose as a fuel line.
10. Spring-loaded clamps are commonly used on fuel lines. These clamps often lose tension over time and may spring back when removed. Replace all spring-loaded clamps with worm-type clamps whenever a hose is replaced.
Metallic highways
11. Metal pipes are often used as fuel lines between the fuel pump and the fuel rail. Carefully inspect the fuel line for deformation, flattening and cracks.
12. If a metal fuel line must be replaced, only seamless steel line should be used, as copper or aluminum line does not have the strength necessary to withstand normal engine vibration.
13. Check the metal brake lines where they connect to the master cylinder and pressure regulator (if available) for cracks or blinding tightening of connections. Any signs of brake fluid leakage require immediate full inspection of the brake system.