Am I going re-checking my work (won't run) on changing the timing belt, I lined up the TDC mark on the crank pulley, checked that both TDC marks are aligned on the cam sprockets. All these marks line up fine. The problem is, when the crank TDC mark is lined up, the piston in #1 cylinder (passenger side front as per service manual) is at BDT? Is TDC not TDC?

90GT - Maui


Uh oh Dan,
The proper procedure for all 32V motors is:
Turn the engine (clockwise direction only) until the top dead center mark on the crank pulley is aligned with the pointer, and the notches on the back of the cam sprockets are aligned with the dimples in the backing plates at the 45-degree position, not the TDC. Then, turn the crank (again, clockwise direction only) approx. 1 7/8 turns to align the 45-degree mark with the pointer. Next, add 45^ marks to each cam sprockets so the belt can be installed in the 45^ position. This is the only position that allows camshaft movement (which, when you're installing the belt is likely) without the possibility of valve to piston contact I sincerely hope you haven't bent any valves. Do you have a set of workshop manuals ??

Best regards,

Hopefully Jim has the answer with a backwards balancer. The numbers will be right side up if you are standing in front of the car.... I just wanted to point out it's important to pull the engine *two* revolutions when doing the t-belt job. Two rotations of the crank equals one rotation of the cam, part of being a 4-cycle engine. Of course if you don't pull two revs then the marks won't align....

Anyway, on the S4, cylinder 1 is at TDC when both rotors are pointed to the left (driver side). In fact, the right belt cover has an arrow on it - when the rotor is lined up with the arrow you have Cyl 1 TDC.

I'm sure you've checked electrical connections. Be sure to check the Temp Sensor II connection.

Let us know! Hope this is helpful.
John Pirtle



Found some conflicting information on aligning up the timing marks for a belt replacement.

One site indicates go to 0 ATDC then rotate crank to 45 degree mark

Another site says go to 0 ATDC then rotate crank one full turn then to stop on the 45 degree mark.

Which procedure should I do?




90 S4


The crankshaft has only one Top Dead Center mark for #1 cylinder.

There are two TDCs, however,  TDC-Firing (or Compression) and TDC-Exhaust.  The crank is in exactly the same position for these two, but the camshafts are in different positions. The only easy way to tell which you are on is to look at the "distributor rotor" direction. You will have the right belt cover off to check the belt anyway. Remember that all directions on a vehicle are with respect to the driver's position. To put it another way, the right headlight is always the right headlight, even if it is on your left as you stand in front of the car. The same thing applies to the cams, belt covers, plugs, heads, etc.

So - with the right belt cover off, turn the crank as if you were tightening the crank bolt until the rotor is pointing at the left fender and the crank damper marking has the "0" at the pointer. This is TDC-Firing. Continue turning the crank one full turn. This brings you to TDC-Exhaust. Continue carefully turning the crank about 3/4 of a turn, watching carefully for the 45 deg mark to appear. Stop with the 45 deg mark at the pointer. This puts the crank at 45 degrees before TDC-Firing.

At this point, all of the pistons are down in their bores enough that none of the valves will hit a piston even if you rotate the camshaft.

Install the flywheel lock. Make a precise mark on the camshaft gears, lining up with the pointer on the plates behind the gears. These are the alignment marks where you install the new belt.

Wally Plumley
928 Specialists


Indicator on Right-Side cam showing TDC firing position on the cover if crank aligned to TDC.

If rotor was pointing in the other direction the cam is on the TDC exhaust position.