August 13, 2006

Project Audi S4 (UrS4): Protecting the Project
Text and Photos by: lskolnick

As we heard in the first installment of Project UrS4, the car is a bit of a fixer-upper. One of the required maintenance items outstanding on the car was a timing belt job. There was no sense in bolting on a bunch of modifications just the have the timing belt snap. Bent valves are not happy valves and holes in the pistons may cause a drop in the compression ratio, but not the kind we were looking for.

The timing belt job on the UrS4 involves removing the bumper, top cross-member and swinging the radiator out of the way. The parts replaced were of course the timing belt, timing belt tensioner roller, water pump, serpentine belt and serpetine belt tensioner roller. All parts used were German made except for the FAG timing belt tensioner roller bearing which was made in Hungary.

Getting ready for serious mods

Another good first step in any modding project is to start with a car that is just plain running well. Project UrS4 at this stage in its life simply needed a tune-up. The valve cover gasket was leaking and spilling oil in to the spark plug wells. The valve cover gasket along with the spark plugs (and for good measure the airfilter) were therefore replaced. The C4 S4 like the B5 S4 requires Bosch Platin F5DPOR spark plugs and seems to run poorly on most everything else. The valve cover gasket and air filter were OEM replacements.

The bypass valve was replaced as a preventative measure. The original unit was replaced with a 710N bypass valve from the 1.8T TT quattro.

With the timing belt replaced, the car tuned up and the bypass valve replaced project UrS4 is ready for some serious mods. That will have to start in the next installment. The owner did take the opportunity to install a set of clear corners while the front end was apart, however.

Resources:

  • Project UrS4 Photo Gallery
  • Original 'S' Cars Discussion Forum