A friend of mine has this car with the six cylinder. He hired a guy to replace the water pump for $175. But now the guy wants $400 more to time it, which includes a part, which part I do not know.

Does this car need re-timing when the water pump is replaced? What part could be involved? What the hey?

 

For Audi 100 2.8 V6 - yes, you need a special tool to align camshafts on both heads.

I would consider:

1. renting one from a shop
2. making this actually a simple ruler with 4 pins by yourself (google for this)

 

The guy that took on the job of replacing the WP does not know Audis.

It is common practice to replace the Timing belt, water pump, tensioners, and front seals all at the same time. And it takes a special alignment tool to get the cams timing correct. Go to the A6 forum and do a search on timing belt or water pump and you'll se what I'm talking about.

Your friend either needs to do it himself or find a "real Audi guy" Check Blauparts for TB lits and instructions

PS the tool can be ordered on-line thru Ebay with the crank locking pin for around $125. A complete timing belt -WP etc job can run between $1,200 and $2,000 depending upon who does it.