How do i adjust the tensioner on the alternator belt of my 1997 vw jetta trek 4cyl.

Ask the guys at a VW wrecking yard, they know about interchangability. The rest of the world just fixes what they have.

as the alternator IS the adjuster for the tension of the belt,it is a simple task of undoing the alternator bolts/nuts and pushing it inwards to fit belt,then pull it outward to tension belt to correct tension...

Timing Belt Spanner Wrench
AST tool# H 2587-1

- Used for the Adjustment of the Timing Belt
- Applicable to 2004-2005 VW Golf, Jetta Pump Duse and 2002-2005 Audi 3.0 V6

Used for the adjustment of the timing belt.

2009 Suggested user price: $52.67

Assenmacher Specialty Tools
1 800 525 2943
Timing Belt Spanner Wrench
AST tool# H 2587-2

- Used for Adjusting the Timing Belt Tension

• Applicable to 1999 and later VW Golf and Jetta, Passat and 1999-2003 VW Beetle with 2.0L Gas Engine and 1.9L T.D.I. Diesel Engine

Used for adjusting the timing belt tension and is comparable to VW tool# T10020. Applicable to 1999 and later VW Golf and Jetta, and 1999-2003 VW Beetle with 2.0L gas engine and 1.9L T.D.I. diesel engine.

2009 Suggested user price: $52.67

Assenmacher Specialty Tools
1 800 525 2943

thats because there is a tensioner pulley

it is likely sprung loaded to tension the belt
at times they fall off
folow the belt placenment make sure the belt has all conections
some vw also have a sensioner that is under motor or at least a pain to get at

theres 2 bolts! one has a slack adjuster made into it and a bolt that you losen on the front of the alternator then take a rachet and 13 mm socket and ext and crack the top slack adj bolt clockwise and feel the belt !! when you have less than a 1/4 inch up and down play! stop!! and tighten the mount bolts back up

the v belt tensioner is spring loaded therefore it self adjusts the belt.i susjest a new tensioner and belt.good luck with repair.

Alternator belt routing — all except VR6, with power steering, no A/C

1. Disconnect the negative battery cable.
2. Disconnect the wiring from the alternator. If necessary, mark the wires with tape or other means to ensure they are connected properly upon installation.
3. Loosen the belt tension, and remove the drive belt from the alternator. On VR6 (AAA) engines only, remove the belt tensioner from the cylinder head.
4. Remove the alternator adjustment bolt, followed by the pivot bolts.
5. Carefully lift the alternator from the bracket. To install:
   
6. Hold the alternator in position on the mounting bracket, and install the pivot bolt. On later engines with automatic belt tensioners, install the upper mounting bolt.
7. Install (but do not tighten) the alternator adjustment bolt (earlier models only).
8. Place the alternator drive belt on the pulley.
9. Adjust belt tension and tighten the mounting and adjustment bolts as necessary.
10. Connect the wiring to the alternator. If tape was used to identify the wires, make sure it is removed once the wires are connected.
11. Connect the negative battery cable.

check out www.autopartsdirecttoyou.com they got mostly evreything if its not listed call them up they can probably get it

You need to thread a 10mm diameter bolt into the threaded hole on top of the belt tensioner ... be sure to get one that is long enough .. you should be able to get it at your local auto parts store and/or possibly a home depot, lowes etc

Cars over 10 yrs.. Good Luck!
Try your local Locksmith with proof of ownership mine charges $35. after we had AAA tow the car to his shop, o/w add the cost of a Housecall.