I found out about this sorry state of affairs about 6 months ago. My first A4 saloon was 2002 1.9TDI and provided me with confidence to trade in for 2005 B7 Sline saloon - Yes, with BLB engine and chain-drive oil pump. I had never noticed any change in the sound of the engine during my 16 months ownership of the BLB, but decided to take it to an INDY 9at 60k). They reported that they are doing between 1 and 2 conversions a week. I also had the lumpy idle - they suggested that was most likely the tandem pump problem. Oh, and while the work required to rectify it was being done then I may as well get the injectors cleaned too. They guy says that it sounded like I was looking at best part of £2200 for design faults.
The tech did have a good listen and reckoned that on a scale of 1-10, mine was at 2. He said he wouldn't worry about it at that stage if it was his car, and that when the problem got worse I would know the sound!
I phoned two head-Audi techs and finally got them to admit that 1 conversion a week 'sounds about right', having previously said they knew nothing of the oil pump issue. When I asked their advice on what I should move on to next, I was told categorically to stay away from the 2.0TDIs, even the newer ones - apparently even the gear-driven pumps are also prone to failure and even 09/10 plates have the tandem pumps sending engine oil through the fuel system. They wouldn't touch the 2.0TDI with a bargepole. I was advised to go back to the 1.9TDI engine. So, it sounded like a good time to get rid of it - a car that I had grown to really like. I was not in a position to pay out any more on monthly payments for my car so I took that advice and found a garage that was prepared to do a straight swap for a 54 plate Dolphin Grey Sport Avant, which I have always admired. The engine sounds much quieter than the 2005 BLB. The garage also changed the timing belt and alternator pulley as requested during my look at the car and I'm so glad with it now.
The Audi techs say that the 1.9 (both old and new by the way) are pretty much bulletproof of any major issues like the one going on in this thread and that they are rarely in the Audi garage for big issues.
I'm glad I did the swap but I'm genuinely gutted for people who have been caught out by this. At one stage AutoTrader was awash with 2005 2.0TDIs, a point which others may have noticed. In the future? I don't know. I'm now pretty familiar with the cars and bring the paintwork back to new as a matter of course and do my own brakes and servicing, so I thin I'll stick with Audi, but may look at the 2.7TDI in three years. Then again, the 1.9TDI may prove to be irresistable and trustworthy.