Technical Boost leak

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Technical Boost leak

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My Uno Turbo has a WOF at last - and being all back together (all trim and seats, seatbelts, headlining, extra sound-deadening etc.) it rewarded me by springing a boost leak straight away... not something I've ever had in the three years I've had the car...

I've fitted the sound-deadening blanket under the bonnet so at first I thought it had to be related to this.

The bonnet closes onto two small vacuum pipes tapped into the larger hose to the brake servo. I noticed one of these fittings was free to swivel in the (very hard) hose, so today I replaced it with new servo brake hose. The new hose is the wrong size (too small) and as I was trying to force it on, one of the plastic T-fittings snapped off :( so I used the other metal T that was for the air-conditioning fast idle (not in use at the moment).

Anyway the result of all this is no change at all - I still have this major leak when the boost starts. It's a loud Whooosh which disappears with a cool chattering-sound during gearchanges. I suppose that means it's pre-throttle, so I've checked and tightened all the large hose clips. It doesn't seem to affect the engine when idling or driven off-boost. It appeared suddenly (thought something had fallen off, but everything's there), so probably something has a split. Sounds as though it's on the driver's side. I can't see anything amiss though - so it's proving to be a challenge! Can't believe the intercooler has suddenly failed, would have thought it would be more gradual...

I wonder if there's any way to pressurise the system to listen for the leak. So far I've tried removing the small pipe from the Microplex and putting in about 15psi, but that just gave a general hissing of air going in, and I guess being after the throttle, it's not much use.

Anyway enough of my ramblings I guess.
-Alex
 
The most common boost leak is the small joiner hose off the turbo to the pipe.

If you like, rev the motor up as much as possible and it should generate some boost, check where the leak is. Remove a plug lead or 2 (earth them with a plug) and it will build more boost.

Check the BOV too
 
Thanks Steve!

Do you still have any spare hoses or are they all sold now? Wish I'd bought some spares :bang:

I have no idea why missing sparks would cause more boost, that's a puzzle to me! :)

Not sure how the neighbours will take to that fault diagnosis method either - might have to do it tomorrow afternoon before everyone gets home...

-Alex
 
The other way is to put the car on a hoist, or lift the wheels off the ground. Drive the car in gear and load it up on the foor brake. I found a leak on my car in the main boost hose (off the throttle body) today.
 
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