Timing Belt Dilemma – teeth stripped

AlfaAudiRob

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Greetings. Prior to posting this I searched the forums and read a number of threads but didn’t find specific enough info to decide what to do going forward.

I have a 2005 A4 Cabriolet 1.8T that experienced a timing belt failure. The history is my brother bought this as a project car with some electrical (top sensor, windows, etc.) problems but it was running and driving fine. He got tired of working on it and handed it off to me. He had replaced the timing belt, tensioner, water pump and roller and put about 150 miles on it with no problem. On my way home it died after 30 miles. No smoke, no noises or anything else that would indicate a catastrophic failure. I tried starting it several times and it spun but sounded like it wasn’t getting compression. I pulled the timing top cover section off and the belt was loose and wouldn’t turn so I did the following:

  • Pulled the plugs and stuck a camera down to see if there was any piston damage. Everything looked OK. I could see the pistons moving up and down fine with a camera when it was cranking.
  • Tested compression and zero compression on all 4 cylinders.
  • Pulled the front forward (per some good Youtube videos) and got the lower timing cover section off and the teeth had been stripped from a section of the timing belt. I think it was near the intake sprocket or the water pump pulley. Stupid me didn’t make note and write it down.
  • The crank turns fine so I thought it might be one of the cams or the timing chain or tensioner.
  • I turned the exhaust cam with a wrench but it seemed to have too much resistance after about 10-15 degrees. I think I just didn’t realize it takes a bit more torque on the wrench to mover over the lobe and pop to the next lobe.
  • Pulled cams, chain and tensioner. Cams look perfect. Cam journals and caps look perfect. Chain looks perfect. Tensioner compresses top and bottom guides when I but some weight on it. I don’t know how strong the resistance should be but it seems to compress reasonably.
  • I put the tensioner, chain and end caps back on and could crank the cams with a bit of force and they’d pop to the next cam.
  • The roller spins easily. The tensioner spins with some resistance but not excessive. The water pump pulley spins by hand with a little resistance, which I would expect since it is moving coolant through the system.


I’m thinking about just putting a new timing belt on, setting the timing, reassembling and saying a prayer but before I do that I wanted to see if any of you experienced Audi guys, of which I am not, had any ideas of why the teeth would strip off the timing belt like it has. I’d hate to put it all back together and have it happen again in another 100 miles.

Any advice or any pointing out if I’ve done something dumb in the list above would be greatly appreciated. I’ve included some pictures of the belt and can add pictures of other components if needed. Thanks in advance for any feedback.

Since I’m new to these forums I’ll be posting on several different forum sites but only one forum per site.
IMG 4359
IMG 4360
IMG 4361
 
The engine has no compression because all the inlet valves are likely to be bent. If the engine has been turning and the cams not in time then the valves hit the piston. It's quite common for the cams to partially seize if there are oil pressure issues with the engine. The chain tensioner end of the head seems to fare the worst.
 
The engine has no compression because all the inlet valves are likely to be bent. If the engine has been turning and the cams not in time then the valves hit the piston. It's quite common for the cams to partially seize if there are oil pressure issues with the engine. The chain tensioner end of the head seems to fare the worst.
Thanks for the quick reply. I was afraid if that. Guess I’ll pull the head tomorrow.
 
Hi if a mod see's this can my reply be deleted, this was an accident,
 
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