My 55 plate Focus 1.8 diesel is sick and I'd be really grateful for any direction on how to resolve the proble, preferably DIY. I was out for a run and I heard a bang and hiss coming from the engine bay. Initially I though I'd had a puncture, such was the sound. The car wouldn't perform, so I limped home with smoke coming from the exhaust. I was even flashed, so it must have been bad. Having researched the problem it pointed to the turbo charger so I removed it for inspection. It seemed fine, with no play or apparent damage so I painstakingly put it back. Now, with the engine on idle, it sound good but when I rev a bit there is a high pitched whine which seems to be coming from the turbo area. If I rev the engine more the whine gets worse and something is smoking near the turbo, though not a lot. I would really appreciate any information that helps me identify the problem and what I should be looking for in a knackered turbo, and that's if it is the turbo. I don't know if it helps, but the A/C has packed in, though the noise doesn't appear to be coming from the area. I daren't run the car just yet to see how it performs seeing as there's smoke when I rev the car when static. I know I could take the car to a garage, but frankiy it may no longer be cost effective and I like to dabble myself.

Sounds like a blown boost hose.  The solid metal one is common to break on the 1.8TDCi so that would be the first one to check.