Plumes of black smoke and hissing from under bonnet - ANY IDEAS??????

[PhilUK]

Hi chaps,

My X developed a problem recently, suddenly noticed loads of smoke from the rear and lots of air escaping under the bonnet.

The car is now with my local indy who has confirmed that there is an air leak somewhere on/after the turbo but he cant locate it.  >:(

Can anyone offer any advice on where to tell them to look? Anyone had the same problem?

This is a daily driver so is being greatly missed! 

All advice very welcome.

Thanks in advance.

[Steamyrotter]

Intercooler, MAF or intervening pipe work.

Poss inlet mnifold but not heard of one failing like that, but there is always a first time??

[PhilUK]

Thanks for the reply steamyrotter.

Is there a best way to determine where the leak is coming from? The indy has advised that it doesnt leak unless there is a load on it and you obviously cant have your head under the bonnet whilst the car is moving.  )

[X5Sport]

An Indy ought to be able to move the plumbing about!  Or even move the engine on its mounts on a ramp!!  Pipework is all on the left side of the engine looking from the front.  Inter cooler is below the main rad. Turbo is front left with the inlet on the forward side.

Diagram of pipes here on Realoem.  Assumed you have a facelift like I did...

The air is fed to the manifold (black plastic 6 armed moulding on top) via the EGR system on the front right of the head.  See piccie below with engine cover removed.  The air filter is under the black cover on the left side of the engine.

[PhilUK]

Many thanks for the info X5Sport.

So an I right in thinking the best way to locate the leak is to manhandle the pipework until you hear air escaping?

Would this still happen without the car moving?

[X5Sport]

You ought to have the car up on ramps and the engine covers off top and bottom so everything can be seen and then start manhandling things.

All that happens in the engine bay when you are moving is that the engine moves a little as it is under load.  It ought to be possible to replicate that whilst on a ramp - might need a lever to force things a bit.

You could also try a long screwdriver or bar and place your ear on the other end to see what you can hear as you move the driver/bar.  Another choice is a bit of tissue on a stick and move it around the pipes, or even the fairly liquid in water trick - spray with a garden mister and look for bubbles..

It could just be a vacuum hose off or split.  If it affects the turbo and stops it spinning up properly then you'll get smoke and lack of power.

[Steamyrotter]

Not advised for long periods you can hold the car on the brakes and rev to 1500/2000 rpm in gear.
That will load the car and get the turbo up to pressure.
However it will heat the trans fluid quickly and could stress the torque convertor.
As i said very short duration should be ok.

Having typed that check everything around the turbo.  a sensor pipe may have popped off??

[strummer]

could just be a split hose

[Osprey]

Same problem on my Passat a few years back..... indy changed the intercooler, cat and ordered a recon turbo when a proper mechanic squeezed a hose and said it's split! £70 plus fitting good as new.

Go for the cheap and easy first and work your way up....don't always think it's something big and expensive