Boost Leak Test - Can hear air coming out of air under intake manifold - 3sgte

[trd_st184]

Hey all,
I did a boost leak test the other day and can hear air coming from somewhere under the intake manifold. I have checked all vacuum lines that I can see, but i'm sure there is one coming from that location. Unfortunately I cannot isolate it. Normally i use water with dishwashing liquid to try find the location on silicone hoses etc.

The motor is a gen 4 3sgte.

[stidnam]

There is a vacuum canister mounted under the bottom of the intake manifold. It may be that?

[Cuts]

I made an ingenious contraption to find issues like this. Basically it's a piece of 3" pipe welded shut one end with a fitting to go to a valve then to a compressor air line, and also a pressure gauge (see bloody terrific and precise engineering diagram below). You can probably see how it works, put it on the front of the turbo, use the compressor to put 5psi or so into the intake system then you can hear for leaks in silence.

[trd_st184]

Forgot to mention I did something similar, using a piece of PVC pipe and used a tyre pressure gauge and the compressor to pressurize the system but its quite hidden away (the spot)

I am pressurising the system from further up the air intake pipe and I have a feeling it may be pressurizing the oil ventilation as well (some of the lines that run off near the air filter actually go to the head.

There is a vacuum canister mounted under the bottom of the intake manifold. It may be that?

Good point mate, I will definitely have a look. Its quite tricky to get to unfortunately. Will have to grab a piece of paper or something and drape it down hoping it may flutter as the air comes out haha.

[jonathan yee]

If you puttng pressure into the inlet manifold air will obv get pushed into which ever cylinders the valves are open on, and then passed the rings into the crank case then back up the oil drain hole out the pcvs.

[mic*]

True jonathan but wouldn't that be plumbed back into the intake system?
I could be wrong but isn't there a boost control solenoid mounted somewhere down under there? Like side of the block or sort of, under the intake manifold. You get to it from under the car to inspect... just a thought.

[trd_st184]

Thanks for all the feedback. I have a bleed valve on the car at the moment, so no doubt doing a boost leak test I would need to remove it.

[wagonist]

When I wrecked the engine in mine, I had a leak from the inlet manifold.
Middle bolt (between 2&3) wasn't tightened properly.

Might not be the issue for yours, but always pays to check the simple stuff