How necessary is timing belt cover?

[urq]

... let me pass along my personal experience on the subject.  

Many, many years ago I replaced the timing belt on my '88 5kSCQA.  I 
followed proper procedures and closed everything up when I was done.  No more 
than a month later I was taking the car to meet up with the local Audi fans when 
all of a sudden the dash lit up and the engine died.  It didn't take long to 
realize that the cam was no longer spinning with the crank.  I had the car towed 
home.

When I opened the timing cover I found that the timing belt had a 1/2" wide 
slice stripped off one end, which then caught on something and tore the belt 
apart.  What I found was that when I did the TB service a very small piece of 
sharp paving material had gotten inside the timing belt area.  The clearance 
between the belt and the oil pump casting is deliberately small to minimize the 
chance that the belt will jump a tooth on the crank pulley.  That tiny sharp 
triangular piece of grit nestled between the oil pump housing and the belt and 
wore a groove into it until the belt failed.  


If it weren't for that close tolerance situation there would be less need for a 
cover ... V-belts and serpentine belts don't need them ... but since we're 
likely talking about an interference engine where serious problems can result 
from a belt breaking it is wise to keep the cover in place.  


Steve Buchholz

P.S. - The saddest part of the story is that the car has lived in my garage 
since that day.  There is a replacement MC engine on a stand sitting in the next 
bay ... and I'm finally working to get the engine and new transaxle installed 
... 




________________________________
From: Christopher Gharibo
Sent: Fri, June 14, 2013 4:04:19 AM
Subject: How necessary is timing belt cover?

I have a '91 100q and CQ and have thought about removing the upper timing belt 
cover on one or both cars. 


Will my cars suffer any adverse consequences if I permanently remove the upper 
timing belt cover?  


Thank you.  
_______________________________________________