That's part of the EGR valve pipe-work isn't it? That means air will be getting in and you'll be running lean, so the clever computer engine management will be trying to make it run richer, is the way I see it, and it won't be able to cope. Needs a bit of stick-tape over it!

In that case, I'm quite wrong and we'll have to wait for a more knowlegable contributor! The only other bit on a diesel that I can think of is the turbo, which needs a blast of exhaust gasses up it.. or if it's the output of the turbo, then it will force air into the inlet manifold... but I can't see, from the picture, that it goes to the turbo. Or... Is the pipe split because there's air pressuring it when there shouldn't be pressure in there? Unfortunately, I don't know anyone who's got one of these, or I'd be looking under the bonnet! I still like a challenge, now and then.

Edited by MrEckerslikefromRamsbottom on 10/09/2014 at 18:08

That looks like the charge air hose (turbo boost hose) from the intercooler to the inlet manifold. It'll need a new hose as sticky tape just won't do it.

The air being blown out of it is the pressurised air from the turbo that should be going through the intercooler then into the inlet. Any loss of pressure from splits in the charge air system will cause the car to struggle to achieve the correct boost pressure hence the lack of performance / limp mode.

The oil mist is quite normal and shouldn't be a concern as all turbo diesel engines have a small amount of oil mist in the intake / intercooler. Fit a new or good second hand hose and you should be OK.