Audi Audi S8 2019-present Fuel System Bolt Torque Specifications

Using the correct torque ensures a proper seal, preventing fuel leaks which can be dangerous and cause engine damage. Under-torquing can lead to leaks, while over-torquing can damage the bolt, threads, or the fuel component itself, potentially leading to premature failure and fuel leaks. For example, if a fuel rail banjo bolt is overtightened, it can crush the sealing washers leading to a leak; undertightening could mean the rail will come loose and leak.

The most reliable source for torque specifications is the official Audi repair manual for your specific vehicle year and model. These can be accessed through official Audi service resources, professional automotive databases (like Alldata or Mitchell), or from a licensed Audi technician. Never rely on unofficial sources like online forums for critical torque specs.

It's generally recommended to replace single-use bolts, especially those in the fuel system. These are often torque-to-yield (TTY) bolts which stretch when torqued and therefore cannot provide consistent clamping force a second time. Reusing these can cause leaks, and may lead to fuel system component failure, creating a safety risk and potential for expensive repairs.

Always use a calibrated, high-quality torque wrench with the correct torque range for the job. Digital torque wrenches are preferred for accuracy, but click-style torque wrenches are acceptable if used properly. Ensure your torque wrench is calibrated regularly for accuracy (usually annually) since improper calibration can lead to incorrect torque readings.