Doing a vac leak smoke test, should the brake booster vacuum pump be blowing smoke out?

[jeffmills69]

Trying the smoke test again to find a vac leak but this time did it from the brake booster hose and noticed smoke billowing out from the vacuum pump and figured it may only be a one-way air flow where there is some sort of valve stopping air from going out.. is that correct?


If this isn't it the next thing is a compression test

 

[Fu Manchu]

My guess is you should not be seeing smoke from there.

 

[shane_3800]

PCV valve must have a leak.

 

[jeffmills69]

PCV valve must have a leak.

It's an LFW, is the PCV valve just the silver thing with 2 holes in the valve cover side and 1 hole that goes into the PCV hose? What makes you think that anyways?

 

[shane_3800]

It's an LFW, is the PCV valve just the silver thing with 2 holes in the valve cover side and 1 hole that goes into the PCV hose? What makes you think that anyways?

Pressure should not make it back past the PCV on the booster. Smoke tests usually use about 2psi.

 

[Fu Manchu]

PCV is a Tesla valve design and has no one way check valve like the older V6 etc.
The booster has its check valve on the booster, so should be an unhindered flow into the vacuum system if OP disconnected the booster hose to leave the check valve in.

 

[jeffmills69]

Pressure should not make it back past the PCV on the booster. Smoke tests usually use about 2psi.

Is there a valve in the hoses in this pic?
BB = Brake Booster VBB = Vacuum Brake Booster IM = Intake manifold

I was blowing in through BB which splits off with a T piece to the IM one way and the VBB the other way

Now that I think about it would smoke even make its way into the valve covers like this? Might actually try blowing into each side and see if theres a leak either side..

 

[Fu Manchu]

Yes it will make it into the valve covers via the PCV, which does not have a check valve.

 

[shane_3800]

Yes it will make it into the valve covers via the PCV, which does not have a check valve.

The PCV is a check valve.

 

[shane_3800]

You're meant to pressurise the into then intake pipe that connects to the throttle body.

We have a smoke pro at work and it has a big rubber cone for this purpose.