How to tighten the alternator belt

How to tighten the alternator belt

Got that annoying squealing noise coming from under the bonnet? It's probably a loose alternator belt. Luckily, it's pretty easy to fix.

You tighten/loosen the belt by actually moving the alternator towards the engine (to tighten) or away from the engine (to loosen).

Tighten or loosen the alternator belt

Note that the alternator belt is also the water pump belt.

Step 1 - Remove the timing belt cover to access the lower alternator bolt and loosen it off.

We're not touching the timing belt, just getting this cover out of the way to make it easier to reach the lower bolt on the alternator. You will see a hole in the plastic shrouding where the bolt is located. Its a 7mm hex/Allen head. Loosen this off but do not remove it.

Hex bolt to loosen Mk1 Golf Alternator

Step 2 - Loosen the top alternator bolt

You'll see a bolt connecting the top of alternator to a bracket protruding from the side of the engine. You'll also notice this bolt is connected to a nut with teeth cut in it - ignore that for now. Loosen the bolt, but again do not remove it.

Step 3 - Tighten the belt by pushing the alternator towards the engine

With both bolts loose the alternator should 'swing' back and forth freely. Pull (or push) the alternator towards the engine to tighten the belt. Now, here's where that 'toothed' nut comes in handy - with the belt reasonably tight you can use a spanner on the toothed nut to ratchet the alternator back a few more millimetres.

Once you're happy with the tension (a good trick is taking a section of belt between the two pulleys and seeing if the belt can twist about 90 degrees) tighten the top bolt. Then, tighten the lower bolt and replace the timing belt cover.

Turn the car on and inspect the belt to insure nothing is getting in its way.

Toothed nut

 

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