V6 belt tensioner

[AlfaNeely@domain.elided]

In a message dated 09/19/2002 6:18:00 AM Central Daylight Time, 
owner-alfa-digest@domain.elided writes:


> 
> Date: Wed, 18 Sep 2002 22:39:47 -0400
> From: Joe Elliott <jee@domain.elided>
> Subject: V6 belt tensioner
> 
> What is it about the mechanical detensioner that makes it slack off 
> if you turn the engine backwards?
> 
> 

       Follow the route of the timing belt from the crankshaft to the driver 
side camshaft to the passenger side to the distributor drive.  All that has 
the timing belt in tension when the engine is running and the crankshaft is 
pulling the valve train.
       Where is the detensioner?  It is in the slack area between the 
crankshaft and the distributor drive.  At that point, there is no tension in 
the belt and a small spring can remove slack from the timing belt.
       Now imagine turning the engine backwards.  The crankshaft will pull on 
the belt putting tension immediately on the detensioner.  With that pressure, 
the detensioner will do just that - it will detension.
       The same thing will happen on the four cylinder timing chain.  
However, the tensioner on the four is locked in place with a bolt.  Loosen 
that bolt and turning the engine backwards will push the tensioner back into 
the block.
       On my first Alfa rebuild years ago, I failed to get the wedge properly 
into the tensioner.  The bolt bottomed on the spring, which eventually let 
go.  When the throttle was lifted at about 5000 rpm, slop was let into the 
chain and all the intake valves became bent.

Ciao,
Russ Neely
Oklahoma City
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