Going to look at a 2001 A4 today. It has 107000 miles. What should I look for? Open oil cap and look for sludge? New timing belt...can I see if it has been replaced visually? What else should I watch out for?

 

You should look for one of the thousands of threads on this topic.

 

Oil cap, yes, the timing belt has its own cover so you couldn't tell visually.
Having just recently bought an A4 I wish I would've looked for a few things:

Remove the black engine cover (has the audi emblem, made of plastic, has 4 clips that can pop right out, no problem), check breather hoses, vacuum lines, even if you don't know what it is make sure you don't see cracks or rips. Some of these are costly lines. One hose that I need to replace is $75 for the part alone.

You'll get a bit dirty but check out the control arms and cv boots. Turn the wheel all the way right, check behind/inside your front left wheel for any cracked/ripped/deteriorating rubber. Do the same for the right side. I'm about to DIY my own control arms (http://i45.photobucket.com/albums/f9...n/DSC01225.jpg) and boots but replacing these things can be costly and its better to know ahead of time.

Hope that helps a bit

 

^^^this. Also the stick post right at the top of the forum called FAQ. there just might be one or two things in there that are Frequently Asked...

 

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