I just rebuilt the head of my 2003 1.8t a4 quattro and did the timing belt replacement because the water pump froze, killed the timimg belt and bent all the valves. Started up fine, but after 1 minute of idle the tubo started smoking, smelled a little like rubber, so i cut it off, cleared all of cel codes from the rebuild, and restarted. Heard some clanking from the turbo/engine, while just idling the trbo starts whining and the engine speeds up a little, then the turbo whine dies down and the engine almost stalls, then the turbo whines again etc. for a few cycles. The turbo started smoking again so I cut it off...checked and no cel codes. The turbo was replaced by the stealership ($2,500) about 18 months ago, so its a new turbo. I did not cover the turbo intake where the exhaust manifold attaches while I was working on the engine, so maybe a wire from the wire brush or a piece of dirt dropped in there? Or maybe there is another issue with oil supply or coolant supply to the turbo that is causing it to fail. What's going on with the turbo reving up and down at idle (vac leak?), and if its smking is it 100% sure that I need to replace? I hate to spend another $600 on a new DIY turbo job if not needed when the one I have is only 18 months old. Ideas? Thoughts? Thanks in advance for any response!!

 

update with today' findings...found a leak in the vac hose at the rear of the engine behind the intake manifold. There is a plastic y-shaped connector that the plastic had broken, allowing the link. Replaced the y connector and the turbo now is bahaving. Took for a test drive (first since the head rebuild) and it runs with lots of power. So apparently the vac leak can cause the wastegate or something to not work right and was causing the turbo to do odd things. The smoke seems to have burned off, so I am no longer concerned that turbo is failing. However, there is a coolant leak that looks like it is coming from the rear flange on the back of the head. I replaced that flange when I rebuilt the head, but there must be a leak. Crap...its a pain to get back there and I got to take lots of crap off to get to it, but at least I think my turbo is ok. Thanks