Checking and replacing pipelines located under the hood

Warning: in these models of vehicles, the electric fan may operate with the ignition off. When working in the fan area, turn off its motor or disconnect the negative battery cable.

Warning: Air conditioning hose replacement should only be done by a qualified technician, as this requires special equipment to safely depressurize the system. Do not dismantle the air conditioning unit if it is under pressure.

General information

1. Excessively high temperatures under the hood can cause destruction of the rubber and plastic lines of the engine. Periodically check for cracks, loose clamps, leaks and hardening of materials.

2. For specific information on coolant hoses, see section 15.

3. Most (But not all) pipelines connected with clamps. Make sure that the clamps at the pipe connections do not loosen and there is no leakage. If there is no clamp, then you need to make sure that the hose has not stretched or hardened at the point of contact with another part.

Piping system PCV

4. To reduce hydrocarbon emissions, gasoline blown through the crankcase passes through the PCV valve in the valve cover into the intake pipe through a rubber hose. Gasoline mixes with air entering the intake pipe and burns in the combustion chambers.

5. Check the PCV hose for cracks, leaks or other damage. Disconnect it from the valve cover and intake pipe, check if it is clogged from the inside. If the hose is clogged, clean it with solvent.

Vacuum hoses

6. Usually, vacuum hoses, especially those used in exhaust systems, are distinguished by color or colored stripes fused into them. Different systems are suitable for different hose thicknesses, flattening resistance and temperature resistance. When replacing a hose, make sure the new one is made from the same material.


7. Often the only reliable way to check a hose is to completely remove it from the vehicle. If there are several such hoses, be sure to mark each of them and their supply points so as not to be confused.

8. When checking the vacuum hoses, be sure to also check the T-shaped plastic connectors. Check the connectors for cracks and the hoses where they make contact with the connectors for buckling that could cause leaks.

Fuel hose

Warning: When inspecting or servicing fuel system components, a number of precautions should be taken. Work in a well-ventilated area and avoid open flames, cigarettes, lighters, etc. or uninsulated lighting bulbs in the work area. Wipe up oil stains immediately and do not use fuel-soaked rags there. where it can ignite.

9. Fuel lines are normally under slight pressure, so be prepared to receive escaping fuel when disconnecting a line.

Warning: If your vehicle is equipped with a fuel injection system, you must depressurize the fuel system before servicing it. The procedure for reducing the pressure in the fuel system is described in chapter 4.

10. Check all rubber hoses for possible deformation and abrasion. Pay particular attention to hose bends and connections.

11. To replace fuel lines, use high quality hoses that are usually printed with the word Ruroelastomer (fluoroelastic)

12. Spring clamps are usually used on fuel hoses. After a certain time, such clamps lose their original elasticity. Therefore, we recommend changing the spring clamp to a threaded clamp when replacing hoses.


Metal pipelines.
13. A section of metal tubing is often used to supply fuel from the pump to the injectors. Carefully check for possible bends and folds in the tubes, as well as the appearance of cracks in the folds.

14. When replacing a metal section of tubing, use only seamless steel tubing as copper and aluminum tubing is not strong enough to withstand engine vibration.

15. Metal pipelines of the brake system should be checked at the junction with the main brake cylinder for cracks and loosening of the connection. At the slightest sign of a brake fluid leak, the entire brake system should be checked immediately and thoroughly.