Boost leak testing - problem or spastic mechanic?

[iDub]

The mechanic in question being me...

I attempted a boost leak test yesterday. Plugged the big bung into the MAF->Turbo hose, the mid-size bung into the IC->Inlet hose, and the small bung into the DV(?)->Inlet hose (the small one on the back of the inlet. I plugged the hose side not the inlet side). Started to pressurize the system and I could see the MAF hose expanding, but I could also hear a whooshing noise underneath it. Sounded like it came from the DV area. I couldn't get any pressure to register on the gauge. Unfortunately I wasn't able to investigate further.

Does this sound like there's a problem, or have I cocked up the fitting of the bungs?

The car normally peaks at 1 bar on WOT then backs off to 0.6. I never get more than 0.6 bar unless on WOT. I know this isn't right, hence the test.

Given that I couldn't get any pressure on the test, but it does hold pressure (albeit lower) on the road, does it sound like I cocked up the leak test? I couldn't see anywhere else to put the small bung!

Matt

[Rusty]

Should plug the breather, not the DV

[iDub]

Where's the breather? I couldn't see it in any of the guides! I take it's futher down in the MAF->Turbo hose?

[s2_bo]

Its on the maf hose just after the maf, connects to the camcover on an ABY and to a pipe that runs outside the head next to the exhaust cam on a 3b.

THis has to be blocked incase there are any holes in the breather system.

The DV doesnt not need blocking off or disconnecting.

He can also do a test by just forcing air in to the maf hose at the maf connection with the breather blocked off. But leave the IC > Inlet connected. This will also test your inlet manifold and all the vacuum hoses.
You wont get a completely leak free test this way as the valves tend to leak a little but it should be guite tight.

[iDub]

Right, excuse the photos - it's dark!

So is this the breather? Didn't expect a valve to be attached to it.



This is where I put the bung yesterday.

[lind4hl]

No, that is the WGFV( wastegate frequency valve

[iDub]

Oh, and my pressure valve is on the medium size bung the goes in the ic->inlet pipe so am I right in thinking there's no way of pressure testing the whole system with this kit?

[iDub]

No, that is the WGFV( wastegate frequency valve

Thought as much. I can't seem to find the breather then! Does anyone have pics of a std hose and the breather location?

[Rusty]

Breather is the pic you have taken, with the alloy pipe sticking out of it.

[s2_bo]

Yeah you can see it in the pic, once end attaches to the cam cover connection and the other connects further down on the maf hose.
You can see both hose clips in the picture too.

Good luck

[iDub]

Ok, then I did block the right one! Just explained it badly. It looked like it came from the dv. Dunno why I said inlet earlier either. I unplugged the hose from the cam cover and put the bung in it.

Back to my earlier post then, the wooshing noise - bad then? If it was a big leak then surely it wouldn't boost at all.

[s2_bo]

Even with a big leak you will get some boost. But your turbo will be working hard to make it.
I would check over all the pipework and try to track the leak, you can use soapy water to show up any holes.

[iDub]

Cheers for your help Bo (and others as well). Given that it sounds like the leak is underneath the headlight it's going to be a right b'stard to get to. I'll wait till I get a dry day and start taking the damn thing apart to track down the leaks. Good call on the soapy water. I'll dig out the little spray bottle!

[lind4hl]

i would guess turbo->ic hose then

[s2_bo]

You can get to it from underneath if you take off the undertray and put the car on axel stands.
If you adjust or remove any hose clips then its always good practice to replace them with new ones as they tend to start spinning when you tighten them up.