# How to properly find a boost leak



## syntrix (Aug 20, 2000)

By pressurizing the intake tract post turbo, you can listen for hissing or use a soapy water solution to look for bubbles.
You could use a coupler and attach to the turbo inlet with say a paint can cap and a fitting. But the problem here is the rear pcv will allow pressure (where there should have never been pressure to begin with) to get into the crankcase. If you pressurize the crankcase, bad things could happen if you don't block the port, which is a pita to get to.
The factory service manual calls for using a vw pressure tester (expensive), but also lists a separate part for fitting post turbo, between the hard pipe and the intercooler. The factory manual also says to not pressurize more than .5 bar. Let's see what is needed.
VAG 1687/5
Various fittings
Regulator
Pressure gauge
This is just a mockup that I will be using on a friend's car. It is ONLY the adapter on the VAG part number, and you have to figure out all the fittings. 

















This is probably the most proper way to check for boost leaks. Just be sure that you use a regulator that you are familiar with, as we would hate to see you hit your air compressor psi of say 120 psi :shock:
A safer and probably easier way would be to maybe use a 12v tire pump and figure out the fittings to go to the adapter. Of course, you should always consult the factory manual and throw in two bits of common sense.


_Modified by syntrix at 6:06 PM 5-8-2008_


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## staulkor (May 21, 2007)

Whenever I do a pressure test, I just take off my intake filter and attach a 2" pcv end cap with a compressor quick connect and gauge on it and *open the oil cap* and pressurize to 7psi. It will slowly leak out of the rear pcv and throttle pipe, but slower than you think and it gives you enough time to test connections with soapy water.


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## 2pt0tee (Apr 28, 2008)

*Re: (staulkor)*

Good tips http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


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## [email protected] (Sep 4, 2007)

It's nice to have a manual pump IMO. You can easily be sure not to over pressurize the system and there's essentially no background noise that could prevent you from hearing a leak.


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## magilson (Apr 18, 2005)

*Re: ([email protected])*


_Quote, originally posted by *[email protected]* »_...and there's essentially no background noise that could prevent you from hearing a leak.

http://****************.com/smile/emthup.gif


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## [email protected] USA (May 17, 2007)

*Re: How to properly find a boost leak (syntrix)*

There is no way to 100% seal the system so an air compressor of some sort is needed. You'd be pumping for days to fill that volume thats constantly leaking in a normal manner.
The best way i've found and have been doing for years can be done for about 30 bucks at home depot.
you'll need a PVC piping cap with an OD close to the size of your inlet 5 bucks
Silicon coupler with clamps, usually the ones from your aftermarket intake are fine. free-5 bucks
Airline regulator with gauge 20 bucks
2 male and 1 female air line connectors

Drill and tap center of pvc cap and install male airline fitting. I'd suggest teflon tape but really it probably won't leak much at all since its a pipe thread into plastic.
Install male airline connector into inlet side of regulator and female into outlet side of regulator.
Setup will go airline into regulator, regulator into pvc fitting installed into inlet.
you really need to crank away to get pressure to even start flowing so start turning slowly and once you have a few psi in it let it stabilize, get to 5psi or so check.. 10 check.. etc etc. I wouldn't go over 20psi since most cars aren't running that high.

I would block off the intake manifold to pcv connection, just pinch with needle nose vice grips if testing a car with say the eurojet pcv fix. If you don't have that a small piece of silicone and a small PVC cap will do the trick.
Also the pcv connection at the turbo will fill the crank case with air which is no good. Take off the metal pipe where it meets the turbo and slide the gasket out. Trace the gasket on a thin piece of aluminum, can get like 3 ft (way to much) of 2" wide 1/8" thick for a few bucks at home depot. Cut that out and bolt in place of the gasket.
The VW part i great since its not tappered and its knurled so it holds in really well at higher pressures . If you do the PVC method just rough it up with some sandpaper and don't put your face near where you clamped it in place I suggest putting something with some weight like big channel locks over the airline near the regulator so that if it does pop out it limits it movement. Usually doesn't go far but you may want to check your boxers


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## syntrix (Aug 20, 2000)

*Re: How to properly find a boost leak ([email protected])*

Plus the cost of the vw part, but it makes it a LOT easier than tapping off the rear PCV.
Good note on pressurizing (don't do it) the crankcase through the rear pcv Chris http://****************.com/smile/emthup.gif


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## [email protected] USA (May 17, 2007)

*Re: How to properly find a boost leak (syntrix)*

Where does the VW part connect that you wouldn't have deal with the rear pcv?


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## syntrix (Aug 20, 2000)

*Re: How to properly find a boost leak ([email protected])*

Rear most end of the intercooler inlet pipe. So it excludes the hardpipe off the turbo.
edit:
turbo outlet -> lower hardpipe -> XXX -> rubber hose coupler with special fittings -> intercooler
Or it goes at XXX http://****************.com/smile/star.gif


_Modified by syntrix at 6:20 PM 5-30-2008_


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## rastta (Feb 22, 1999)

*Re: How to properly find a boost leak (syntrix)*

I have one of these - since I was too lazy to build it myself. Works great.









http://www.modshack.info/Pressure.htm


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