View single post by Judson Manning
 Posted: 05-15-2006 12:12 pm
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Judson Manning

Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406
To be honest Brett, it's somewhat of an art based on the unfortunate experience of losing 3 engines to skipped timing belts.

Some rules of thumb:

1.  Start with the engine cold and using a 3/4" wrench, turn then engine by hand so the belt tension on the crank-to-exhaust sprocket section is at its maximum.

2. When the crank-to-sprocket section is at its tightest, the accessory-to-intake sprocket section should be at its most flexible.  Using your thumb and index finger wiggle the belt up and down.  It should flex roughly 3/8" to 1/2" in either direction with moderate effort. 

At the same time, you should be able to twist the crank-to-exhaust sprocket section of the belt 45deg, again with little to moderate effort.

3.  When you think you've got it right, start the engine.  While the engine is heating up, observe the belt and see if it oscillates up and down (accessory-to-intake section).  If any, it should be minor (1/4").  If the belt is too loose it will oscillate far enough to jump teeth on the intake sprocket and trash the engine.

4.  Repeat the above procedure when the engine is HOT (not just water temp).  Now there should be a significant difference in the accessory-to-intake section tension.  Wiggling it this time should only produce 1/2 as much movement.

5.  With a new belt, if its too tight, the lettering will wear off quickly if the belt is too tight.

6.  It's always a good idea to check/adjust the belt every 3 months and/or 3000miles.  The belt itself can last a life-time, but without close attention it can wear, get loose and trash your engine.