Audi Repair: Car will turn over, but will not start, compression tester, compression test

Question
QUESTION: Our 2000 Audi A4 1.8T shut off while driving and would turn over but not start (there was no check engine light). Upon inspection (after being towed home) we found the timing belt was bad.  We have replaced all four belts in the front, replaced the fuel filter and spark plugs.  After all of that it will turn over, but  still will not start.  The fuel pump is working, we have spark on all four plugs, the starter and battery are working fine, and we have fuel.  If you have any idea why it still will not start please help.

ANSWER: Well I hate to say it, but I think you need to do a compression test.  When the timing belt breaks, typically you bend some valves.  Do a compression test and let me know what the readings are.  Does the engine sound the same when turning over?  Let me know,  Jan

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QUESTION: We had the test done per your advice with a compression of 0 psi on each of the four valves.  A proper working threaded compression tester was used and the test was performed properly.  As far as the engine sounding the same, we were not sure if you meant before it broke down (which it does not) or doing the test (which all four did sound the same).  Hope this helps and we are very grateful for your help, Thank You :)

Answer
You have no compression.  Who replaced the timing belt?  The timing belt has to be put in exactly the right place, with both the camshaft and the crankshaft at their marked positions.  When the timing belt breaks, the crankshaft keeps turning but the camshaft stops, this means that some valves stay open, and unfortunately with modern engines, the valves, when open, 'overlap' the position of the pistons.  This means, when the valves stop open, the piston will hit them causing them to bend.  This is more than likely what happened, but to be sure, and to establish how many cylinders are affected, the timing belt needs to be put on with all the timing marks aligned, and a compression test re-done.  If you are unlucky, most valves are bent.  I just finished an engine for a lucky guy, only 2 out of 20 valves were bent.  Good luck,  Jan