WITH A WARM ENGINE
Air filters tend to be easy to replace. Taking care not to break any plastic hoses or mouldings, detach the air pipes, unclip or unscrew the top cover and lift-out the old element. Ensure that the air-box is free from old leaves and road grot, prior to fitting a new paper element and reassembling the air-box assembly. Check the power steering (PAS) fluid oil level. You might want to extract a sample to verify its colour, but take care in case a suction tool cross-contaminates the reservoir with any other fluid by accident. Dark brown, or black fluid could indicate a potential wear problem in either the rack, or pump. Most PAS systems use automatic transmission fluid, which tends to be red in colour, but there are several different specifications, so make sure that you buy the correct type. Some reservoirs contain filters – clean them as directed in your workshop manual, prior to topping up the system, if required. There is normally no need to change the fluid, but you may decide to do so anyway.
Brake fluid can be checked by looking through the translucent container. Natural wear in the linings causes the level to drop slightly, which is normal. Fluid leaks, however, are not. Check for any signs of leakage beneath the reservoir and master cylinder, as well as under the car. Also ensure that any reservoir filters (see inset pic) are clean.
Brake fluid requires changing every two years. It is preferable to flush-through the system with new fluid, rather than sucking it out from the reservoir and topping it up afterwards. recommends the Gunson Eezibleed one-man brake bleeding kit, which uses air pressure from a tyre to pressurise and top up the braking system… …while you connect a tube to each of the car’s bleed nipples and observe that the old fluid flows out of the system. Air bubbles (as pictured) should not be visible through the tube – if they appear, wait until all of them are expelled. Most cars have a bleed nipple on each brake caliper/cylinder. Jack up and support each side of the car and, from within the wheelarches, check the metal brake pipes for corrosion and the flexible pipes for deterioration. The pipe shown in the photo is dangerously perished and, while it is not leaking, it could fail at any time. The pictured hose needs to be renewed immediately. While the wheels are off, ensure that the brake pads’ friction material has more than 3mm thickness remaining – renew any friction linings in axle sets if you are unsure that they will last until the next service. Check that the metal brake discs are free of cracks. The inset pic shows a dangerously-worn pad beside a new one. If your car has rear drum brakes, you’ll have to remove the outer drum to inspect the linings. They tend to be held on with either small retaining screws, or a large central retaining Nyloc nut, which must always be replaced. On some models, the bearing might come out as the drum is withdrawn. Do not drop greasy bearing parts on the floor – grit will shorten their working lives. Ensure there is plenty of lining remaining on the brake shoes. Fluid leaks tend to originate from a failed seal within the hydraulic cylinder. If the shoes have become wet with fluid, they must be renewed in axle sets along with the faulty cylinder, so that there is no risk of a brake imbalance.
Check for frayed handbrake cables and ensure that they are greased, if required. Some models require manual adjustment of the handbrake to reduce lever travel, which can be done by raising both sides of the car and turning an adjuster (pictured) until the wheels lock, then back-off until the wheel(s) spin freely. Some cars require that the cable is adjusted, so check what is appropriate for your model. Diesel engines need to have their fuel filter housings drained annually, which removes any water that could damage the high-pressure circuit. On this car, a pipe is connected to the drain outlet (see inset pic), which is unscrewed to allow the fuel to flow into a receptacle. The top vent screw is opened too (as shown) to aid the flow. Fuel injection specialists recommend that diesel fuel filters are replaced annually. Start by draining the filter housing (see Step 48) and removing the top cover; this can be held in place with screws, or else the top might unwind. Disconnect the fuel pipes and plug, or cover them to ensure no contaminants can enter the high-pressure system. Detach any electrical connectors, too. With the filter canister removed, ensure that the housing is clean, with no metal contamination inside (see inset pic), then follow Steps 48 & 49. Renew the filter and fit a new seal, but lubricate it with clean diesel (not engine oil), prior to refitting the cap and reconnecting the fuel lines and electrical connections. You will need to prime the diesel system so the engine will start; some models do this automatically. Correct bleeding is critical – certain cars (such as Volvo’s five-cylinder units) suffer from damaged pumps if not bled properly – and check if diagnostic equipment is needed. Here, the pipe is connected to the top screw and the bottom drain is tightened, then the primer bulb is squeezed to refill the chamber. Pumping stops when air bubbles cease to be drawn into the tube. Run the engine at a fast idle after bleeding to purge the system of any remaining air. Petrol engines tend to have different requirements; most filters are situated beneath the car, as pictured. Consult your workshop manual on how to depressurise the fuel system. This petrol car has a bleed screw fitted to its fuel rail (see inset pic), but unscrewing it will pour fuel over the hot engine and create a fire risk.
If petrol filter replacement has been neglected, the unions may be stubborn to undo. Be prepared for some fuel to drain from the filter and pipes as the unit is withdrawn. When fitting a replacement, make sure that the arrow on the body points in the direction of fuel flow, which tends to be from the tank to the engine (see inset pic).
Hydraulic clutch systems usually utilise the brake fluid from the main reservoir and compensate automatically for clutch disc wear. Some cable-operated clutches incorporate auto-adjusters, but should adjustment nuts be fitted to your car (see inset pic), follow the workshop manual instructions to either reduce the clutch pedal height and increase free play, or negate clutch slip.