On the Quattro version of the A4, the gas tank is not flat. It is shaped and mounted in the A4 like an upside down U. This allows room for the drive shaft to meet the rear differential. The fuel pump is only on one side of the tank. So, how does the fuel get from one side of the tank to the side that has the fuel pump?
According to Shumburg Audi, there is an injector that picks up the fuel and sends it over to the other side of the tank (where the fuel pump is).
Shumburg stated that the injector (not to be confused with a pump according to Shumburg) is probable making this sound and if the car starts and runs fine, do not worry about it.
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Audi Additional Troubleshooting: When inspecting brakes, check calipers, wheel cylinders, hoses and fittings for any hydraulic fluid leakage.
Inspect the master cylinder, reservoir and proportioning valve assemblies as well. Replace or rebuild as required.
A "spongy" brake pedal or one that's gotten lower underfoot also needs looking into. It could be caused by sticking calipers, worn pads, low fluid or hydraulic system problems.
If you can't "pump them up", then you definitely have hydraulic problems that need work. If you always have to pump them up, at the very least your hydraulic fluid needs replacement.
To check brakes by sound, know how your brakes should sound and listen for out-of-the-ordinary noises.
Most cars have a slight brushing sound from the pads lightly touching the rotors. This is perfectly normal. Sounds to beware of include:
Squeaking may be caused by dust or dirt on the brakes, loose pads vibrating when applied or worn pads.
Rhythmic noise might mean you have a warped rotor. Instead of a solid squeaking noise, it pulsates. In extreme cases, the brake pedal will also pulsate underfoot.
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Replace coolant at or before factory recommended intervals with the proper type, mixture and volume of coolant. Always allow the coolant system to rid itself of air before installing the radiator cap.
Replace the thermostat with the original temperature setting equivalent. The electronics in your vehicle may use that setting for other controls. Do not substitute under any circumstances.
Adjust or replace the water pump drive belt (external) at recommended intervals or more frequently, if required. Check belts whenever you're working on any coolant system components.
Replace the fan clutch and/or fan blade as needed (if applicable). Your Volkswagen's temperature gauge is often your best guide as to when your fan clutch needs attention.
Keep your entire vehicle properly maintained because of the effect timing, idle speed, exhaust and other systems have on your engine's temperature. Your Volkswagen's cooling system is designed to function with all other systems operating properly. It cannot make up for a poorly operating or overheating engine condition.
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Keep your engine and engine compartment, as well as your radiator fins and grill, as clean as possible. A clean engine runs much cooler - and it's much easier to work on.
Replace all cooling system hoses - upper and lower radiator hoses, bypass hoses, heater hoses, manifold coolant hoses and any other hoses on your vehicle - whenever you even suspect there may be a problem.
Replace the radiator/expansion tank cap with the original pressure setting and OE-type equivalent. Some aftermarket substitutions do not seal and hold pressure properly on foreign-manufactured cars. Again, don't substitute.
Replace your water pump with an OEM/OES pump at the first signs of trouble or when your timing belt and tensioner are replaced.
Replace temperature sensors as required by diagnosis. Leave troubleshooting of your sensors to Volkswagen experts who have the proper equipment and diagrams.
For Best Quality Car Service, Speed Towing and Excellent Body Shop Maintenance at Low Cost, visit http://www.RamseyService.com