fusilier

Remember my friend's S4 that died away from home?
Well we trailered it back to Austin and worked on it this weekend. The owner pulled codes and the car reported a cam position sensor and a coolant temp sensor. The genereal concensus on the forum was that the cam position sensor had died.

The car is a 1994 S4 with about 95,000 miles. Yesterday morning, the Austin Audi Club old-school gurus met up to fix this baby. It was a nice 100 degree day in Central Texas. Temps were 95 in the garage. Ken Fluhr, Eric Fluhr, Ed Saenz(owner) and Myself(James B.) were on hand to get things started.

Between the four of us your looking at Two Coupe GTs, Three UrQs, One UrS4, One 5 cyl. 90, One Rally car, as well as a couple new school audis!!

Initial inspection revealed that the serpentine belt and timing belt were in very good condition as the owner reported. But Eric and Ken noted that the car had a very high pitched start noise when cranked. We pulled the front end off and check the timing. The crank was about 5 degrees off. WE thought the thing might have slipped a tooth, but belt was tensioned okay. Then Ken was backing the crankbolt up with a hand socket wrench and was able to turn the crankbolt! It was at this point that we all knew the **** could have hit the fan big time. Okay so the crankbolt was tightened to maybe 30 ft-lbs, whats the worse that could be wrong?? LOL

So we continue disassemble and full off the crankshaft pulley. Here is what we find.
<img src="http://pictureposter.audiworld.com/38899/img_0344.jpg">

Tom Wright(Austin Audi Club lister) shows up about now at the low-tide of the project to see some dejected faces and frowns. We all know he was hoping to see a smooth and well ordered timing belt change.

Looks like the woodruff key on the pulley has sheared off. Notice the fragments of the woodruff key and all the dust which is left or particles. There were only 3 bolts on the pulley assembly and some weird washer inserted in there as a spacer or something. Looked like a major Rig job. It lasted fine for maybe 20K miles.. Anyways. We were finished for the day unless we could fine a new crankpully for a AAN.
Thats not an easy thing in the Audi wasteland of Austin Texas. Eric thinks he has one, but it was actually with Jimmy Pribble. Great, Jimmy's coming over later anyways so we'll have him bring it. An hour or so later here it was.
<img src="http://pictureposter.audiworld.com/38899/img_0348.jpg">

Notice this funky washer which was inserted in the timing belt pully. We think the washer was there to assist in the reuse of the pully with a sheared key? There were only 3 bolts and the two fragments sitting on the old serpentine belt pully. So the old crank couldn't have been balanced. The "new one" on the left is from Jimmy's retired UrS4 of day's gone by. So now Jimmy's there and the count goes up by one UrQ and one Coupe Quattro undergoing a RS2 conversion, and the editor of www.urs4.com!

We're back in business and hoping there was no valve damage. The circumstances described by the owner seem to indicate that the slip occured while the car was on the road at the end of the long road trip and then we speculate the CPS disabled ignition and fuel so that damage did not occur. Its also possible the woodruff key sheared to the point the starter was only turning the crankshaft and not the cams. So perhaps damage in two cylinders only.

We quickly got everything reassembled enough for a test drive. Rob Andrews stopped by for the final crank shaft tightening with his monster torque setup (add one more UrQ). The car fired up and idled perfectly on the first try. No vibrations no apparent valve damage.

Test drive revealed no apparent loss in power. The owner was happy. We didn't change the CPS and will return that part. We did change all the ancillary items except the crank seal.
Actual wrenching time was maybe 4 hours. We had a wait a few hours on the thermostat and the crank pully. Overall pretty smooth with good results. A full cylinder compression test is on order to make sure there is no valve damage. We all think it will do just fine. Very lucky.

UrS4boy

this shouldn't be made part of a normal timing belt change? It would seem that, for whatever reasons, the key is a little weak for the job. I suspect that the valve springs in the S-car engines might be a bit stiffer than the designers thought, i.e. the resistance of the cam depressing the valve springs translates into a larger than expected shear force at the woodruff key. And/or the key material is a little softer than it should be. I wonder if there have been updates in the design/manufacture of these keys between the early 90's and 97.

Dave F.

lskolnick

Wow! Awesome work! I wish you guys would work on my car!

4Driver4

I replace these on my cars as part of the timing belt change.

Rich L.

My buddy was doing a timing belt on a Canadian spec car and the woodruf was broken. They'd done a similar hack to get it running.

Rich

squidix9

Except mine was on the cam pully.

Your stomach drops when you first realize what you've found.