[Vwdiesel] Timing belt life

[Val Christian]

I haven't advertized it (blush) but I have one belt which made it from
the factory to 275 Kmiles prior to change.  When I did change it, 
I discovered that I had never changed it before.  The belt seemed
fine.  

On 1.5 and 1.6 cars I replace the cog belt about every 150 kmiles, unless
something looks funny or it has side wear.  When the diesels first came 
out, I was advised to replace the belt every 60 kmiles.  I did that once.

Thus far, the only catastrophic timing failure I've had is when a 
cog pulley on the camshaft slipped, causing destructive interference 
with the valves and the pistons.  It caused a couple of valves to 
break and pound into the cylinder head and pistons.  The head was 
fixed, and I smoothed out the piston artwork with a wood gouge.
Oh, the factory yellow paint was on the cam pulley bolt.

While the cam pulley bolt is a fine thread, I've since decided to 
torque to a higher limit.  I've considered, but never done, putting
locktite on the mating surface of the camshaft and the pulley.

The biggest "problem" on the cog belt system is getting the tension
right, and keeping it right.  Although there's little change, I will 
usually go back in after several thousand miles, and retension the
cog belt.  I don't like them loose (the cogs and the sprockets wear
faster when they are loose) and I know of a injection pump that 
prematurely failed with a tight belt (you could hear the belt whineing
as they pulled into the driveway).


Val