Engine Compartment Hoses Inspection and Replacement

* Replacement of air conditioning hoses must be performed at a dealer service station or specialized workshop equipped to safely discharge pressure from the system. Never disconnect system hoses or remove system components without first discharging the pressure.

General Information

Exposure to high temperatures in the engine compartment causes rubber and plastic hoses used in various systems to gradually deteriorate. Regularly inspect hoses for cracks, loose clamps, hardening of material, and signs of leakage.

Information on cooling system hoses is given in the Cooling System Operational Check section, and on brake system hoses in the Brake System Inspection section.

Most hoses (but not all) are secured with clamps. Where clamps are used, check that they are tight enough to prevent leakage. If clamps are not used, make sure the hose at the connection to the fitting is not swollen and/or hardened, which could cause leaks.

Vacuum Hoses

Vacuum hoses, especially those used in emission control systems, are usually color-coded or have colored stripes.

Different systems require hoses with different wall thicknesses, heat resistance, and different resistance to collapsing. When replacing hoses, make sure the material of the new hose matches that of the old one.

Often, the only reliable way to check the condition of a hose is to remove it from the vehicle completely. When removing more than one hose, clearly label the hoses and fittings to ensure correct reassembly.

When inspecting vacuum hoses, do not forget to also check the plastic T-fittings. Inspect them for cracks that could cause leaks.

To locate vacuum leaks, a short piece of vacuum hose can be used as a stethoscope. Hold one end of the hose to your ear and probe all vacuum hoses and connections with the other end to listen for the characteristic hissing sound indicating a vacuum leak.

* When using such a stethoscope, be careful to avoid contact with moving components in the engine compartment, such as the drive belt, cooling fan, etc.)

Fuel Hoses

* Certain precautions must be observed when inspecting or servicing fuel system components. Perform all work in a well-ventilated area. Keep open flames (such as lit cigarettes) and unshielded light bulbs away from the work area. Immediately collect spilled fuel with rags, then place the rags where they cannot ignite spontaneously. If fuel gets on your skin, wash it off immediately with plenty of soap and water. When working on the fuel system, wear safety glasses and always keep a fire extinguisher within reach.

Fuel hoses are usually under pressure, so when disconnecting them be prepared for fuel to spray and collect it.

* On vehicles equipped with fuel injection, relieve the fuel system pressure before servicing fuel hoses.

Check all rubber fuel hoses for signs of wear and chafing. Pay particular attention to bends and areas near fittings, for example where the hose connects to the fuel pump or filter, as cracks may form there.

Use only high-quality fuel hoses. Never, under any circumstances, use unreinforced vacuum hoses, clear plastic tubing, or water hoses as fuel lines.

Fuel hoses are usually secured with band-type clamps. These clamps lose tension over time and may slip off during removal. When replacing hoses, replace such clamps with screw-type clamps.

Metal Lines

Sections of metal tubing are often installed between the fuel pump and the fuel injection system. Carefully inspect these lines for dents, kinks, or cracks.

If a metal line section must be replaced, use only seamless steel tubing, as copper and aluminum tubing are not strong enough to withstand vibrations caused by engine operation.

Inspect metal brake lines where they connect to the master cylinder and to the pressure regulator or ABS unit (if equipped) for cracks or loose fittings. Any sign of brake fluid leakage requires immediate thorough inspection of the entire brake system.

Power Steering Hoses

Inspect power steering hoses for signs of fluid leakage, loose fittings, and worn clamps. Leaking hoses and worn clamps must be replaced.