1.6 td whooshing roaring + black smoke

[ridealghp]

When running under high load (e.g uphill or over 60mph) I can sometimes hear a whooshing roaring sound, when this happens there's thick black smoke coming out the exhaust. What do I need to do eliminate the smoke (with nothing in the back, when I hear the sound, I back off a bit, with it loaded I can't hear the sound and spend my entire time on the motorway watching the exhaust via the door mirror)?

1. I'm guessing that the sound is from what looks like a valve on the inlet manifold dumping air pressure?
2. I can see a small hose from the inlt manifold going to a diaphragm operating a lever on the injection pump, could there be something seized/wrong here - how would I check?

Best regards,
Paul

[caveman]

The noise and black smoke indicate to me that you may have a torn inlet hose between the turbo and intake manifold. You are hearing the turbo spool up and the black smoke is because the injection pump is providing fuel for the air that is now missing because of the air leak. Check all the inlet hoses and also make sure you air filter is clean and not blocked.

[ridealghp]

Thanks, I've checked round the hoses and can't detect any leakage. The sound (and smoke) suddenly start and stop rather than gradually intensifying. I've recently replaced the head gasket and did find an inlet manifold leak at the time, however the whooshing roaring sound and smoke are unchanged before and after. Fortunately the head gasket replacement's cured it from throwing all the coolant out. Previously I'd thought the sound could have been the water pump cavitating trying to push water through blocked passages; now my best guess is it's a dump valve dumping turbo compressed air, hence too much fuel for the air available, hence the sound and black smoke always switching in (and out) simultaneously.