Vac Leak Tip, Tricks & Hints

[Manuel Kasko]

Hey guys,

So I have been searching the interwebz about all the tricks to find Vac Leaks.

I also searched SAU and found a few threads with mixed ideas and some of the exact same info.

So most people they say spray it with carby cleaner or start ya bast.

This I guess is a good/bad idea for larger leaks which can be pin pointed by spraying it around and listening for a change in revs.

I have tried this method on my vac leak but still come up with nothing.

Now in my searches people have also used smoke machines to find leaks and there are 2 types you can get either the party ones or the expensive ones made for cars.

Others on youtube have even just used a cigar and a long pipe!

Anyone have any experiences with Vac leaks.

Have you found it?

How did you find it?

Did you use a party smoke machine?

Did you take it to someone for them to find it.

I am considering going down to the party shop and buying myself a smoke machine but then the glycerin worries me having it inside my vac lines etc.

[Hanaldo]

Easy and cheap way man. What size is your intake pipe, 3"? Assuming it is; buy a 3" straight joiner, a 3" cap that fits snugly inside the joiner (I bought mine from Bunnings), and head to your local bicycle store and buy a valve stem for a tyre. Then what I did is used a soldering iron (if it's not an old one, make sure you clean it up afterwards) to melt a hole in the plastic cap and pushed the valve stem into it.

Remove your AFM from your intake pipe and clamp your newly made device on in it's place. Then if you don't have a compressor you can buy one of those $11 portable ones from Supacheap, attach that to the valve stem and pump away listening/feeling for leaks. Make sure you're not pumping 250psi through it, but it should struggle to make even 2psi.

That whole setup cost me about $20, but I already had a compressor. Hasn't failed me yet

[Manuel Kasko]

Might check out a regulator so I can make sure it only pumps around around 2psi.

So this way should make it the whole way to the intake plenum?

Sounds like a good idea because there is no need for smoke or anything.

More then happy to try this tonight.

Anyone else have any ideas.

Just want to get as much info to help other SAU people out if they end up searching this.

[zebra]

Also if you do that, invest in some soapy water in a spray bottle, spray it on suspect areas and it will bubble if there is a leak

[Manuel Kasko]

Hanaldo is this what you did when you had the issue with your intake

[Manuel Kasko]

Also if you do that, invest in some soapy water in a spray bottle, spray it on suspect areas and it will bubble if there is a leak

Guessing do this while the car is dead cold Zebdrew

[scotty nm35]

Sometimes the joiners only leak when hot, once they soften up. It's a good idea to go over every clamp while its hot on the dyno or after a drive as you can get more turns on the worm drive.

I ran mine and a mates STI liberty up to 40psi with the alloy 3 inch bung I made, there were all manner of leaks. lol.

[Hanaldo]

Hanaldo is this what you did when you had the issue with your intake

Nah man, didn't end up needing it. I've used it a few times before though, it's very handy.

You shouldn't need a regulator as the compressor should have one, just keep an eye on the gauge to make sure

[Manuel Kasko]

I went over all the clamps

Even spent the past 4 days putting a new intake manifold gasket on and that still didnt fix it.

Cant wait to knock off work and go put this together.

All else fails im going to buy a cigar and blow that f**ker like a $2 hooker

[urtwhistle]

Pretty much what I did too Hanaldo. the best part about this method is that the engine aint running and you can actually hear, see and feel where there leaking from.

I used an old shiny cricket ball jammed in a joiner just before the throttle body and pvc fitting with a hole drilled into in the intake before the turbo . (PS make sure you clamp it though. 25psi behind a cricket ball with a nice big intercooler fires a cricket ball out damn fast!!!)

[Manuel Kasko]

Pretty much what I did too Hanaldo. the best part about this method is that the engine aint running and you can actually hear, see and feel where there leaking from.

I used an old shiny cricket ball jammed in a joiner just before the throttle body and pvc fitting with a hole drilled into in the intake before the turbo . (PS make sure you clamp it though. 25psi behind a cricket ball with a nice big intercooler fires a cricket ball out damn fast!!!)

So I guess you must have thought the leak was before the intake then.

Why didnt you just let it go all the way into the intake

[Hanaldo]

So I guess you must have thought the leak was before the intake then.

Why didnt you just let it go all the way into the intake

Well the engine is an air leak itself, which is why I said you will struggle to make it hold a lot of pressure. But you should still be able to find where it is coming from.

If you don't find anything with it going through the intake, try the method urtwhistle used, might help.

[LANDSCRIBBLE]

I found without blocking off the joiner to the throttlebody, it wouldnt hold over 40-50kpa. dont forget to block off the vac line to the carbon cannister and the fat hose going from near the bov to the aac valve.

[Manuel Kasko]

Well the big problem is that I think the air leak is after the throttle body because that's where the noise seems to come from.

But I'll try blocking that off the cooler first and I guess that will rule that out

[AngryRB]

i have had a leak in the intake manifold, i found it by spraying all the gaskets with wd40, if its not leaking it just drips, if its leaking it sucks it in while idling, when its on boost, you'd need a dyno and that is when it will spray outwards ..... this is for the intake im talking.. and this info was given to me by DVS JEZ and im so greatful for his input cause i was confused bout it for months... again thanks mate...

[Manuel Kasko]

Well I had oil sprayed on my strut tower which was directly opposite the intake manifold.

So I cleaned it and went out for a boost and it was there again.

But at idle and spray with start ya bast it didn't get sucked in at all just dripped.

I replaced the gasket now the oil has stopped but the squeal on boost is still there and there is a whistle when sitting on -45 vac

That's why I was thinking of doing the pressure test rather then spraying stuff over and over

[AngryRB]

well i had the noise on boost, and the spray sucked in on idle, hmm it will only get sucked in on a vacumn

the whistle is normal with turbo's i think depending on the turbo, but maybe you have a leak on the exhaust side as well? do you have the tags on the 4bolts that connect the turbo to the manifold?

does the car idle smoothly? cause mine was a pig and wont start now , so im doing the gasket and im about to check if the manifold is warped a bit too..

[Manuel Kasko]

I can't get the idle correct no matter how much I play with it. So that's why I'm down to it being a leak.

The whistle only happens around -45 vac on my greddy profec. You can hear the turbos spool but it's a totally different sound and is only recent.

And the high pitch squeel comes around 15psi and wide open throttle

The tabs should still be there because we did them when replacing the turbo but I'll try to suss that out as well.

[Manuel Kasko]

Whipped out the old hose and funnel but couldn't find anything. Actually only thing I could hear was the injector spraying sounds like a hiss well I think it's the injectors.

Is it not normal to smell exhaust fumes under the bonnet?

[battery]

Made this up a while back....

Works great with some soapy water... you discover pretty quickly how rubbish those fat T-bolt clamps are..