'96 VW Golf GL with 2.0 motor. Cold start knock

As long as it goes away within a few seconds don't worry about it. If it was a bearing problem it would knock every time it was started cold, not just now and then.

I'd replace the crank speed sensor .. you can get them on fleebay for 20$.. kind of a PITA to see but it's right under the oil filter. I have a 96 golf gl and have fixed just about every GD thing on the car, but i love it so i will keep fixing it.. This took care of the problem for me

- Joe

at the airbox and not on the intake like the 1997 and later (late 96 as well in south africa)

Check knock sensor bro..

Personally, if it's only a second or 2 when cold, I wouldn't worry about it, other than be sure not to rev it when first started. I've heard many engine do the same, and last a long time. If manual says 10w30, then that's what I'd run in it. What you have to think about, is when you go from 10w, to 20w oil, it's thicker and will take a little longer to get to those critical areas when cold. It may protect a little better when warm or hot, but start-up cold, is more important, as you want the oil to be able to flow fast when cold. If manual recommends 10w30, go with that. I usually will use 10w30, in winter, then 10w40 in summer. Gives you added protection on hotter days, but does not take away from cold start protection.

Remove dash and make sure main electrical plug is snapped in place .Also look for a lose ground wire.

Change your fuel filter.

check the air filter
fuel filter *
test the alternator

I am going through the exact same problem with my 1997 golf 2.0 I-4.   I am making the assumption that this noise is loudest at about 1200-1500 rpm, or atleast most noticeable.   It could be attributed to a faulty catalytic converter which is a necesarry fix (in order to smog), and being that your O2 sensor is hooked into that whole system, you could be potentially giving away a few mpg.  This a relatively easy issue to deal with, and noise should go away when the converter is replaced.

Most likely the noise is the accessory drive belt or the timing belt.