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    Thread: DIY - Pressure testing your intake - Find Vacuum Leaks

    1. 09-24-2004 05:10 PM #1
      I could have sworn someone posted pics at least of how to make one of these a while back but after I posted that I used my pressure tester to make the mbar/voltage chart I've gotten a few IMs about what exactly you do. So since I needed to test mine today after my IC install I figured I"d take some pics and do a little write up.

      There are a few notes I'd like to make.. This is somewhat dangerous.. You are using high pressure to test hoses that are only held on with hose clamps.. your face will be near some of these hoses and they can and will possibly blow off in your face... scaring the crap out of you. Also if not done correctly you are looking to have a huge oily mess in your intercooler pipes which will give you the nice spy hunter smoke effect for a few days so follow the steps to help prevent that carefully.


      We'll start with the oil preventitive stuff:

      1: Remove the oil cap. This will relieve any extra pressure that makes it to the crank case and will prevent oil being forced up into the PCV hoses:

      2: Clamp off the PCV line from the block/valve cover to the intake boot.. This is very important for two reasons... 1 it will again prevent the oil from being forced into the intake causing the smoking when your done. 2 it if not clamped lots of air will be circulating through the hoses and the noises will distract you from actual leaks. You can see that I used a pair of plastic radiator hose clamps. Pep boys and autozone now sell these for a few bucks and are very handy. If you dont' feel like buying them or cant' find them then a long pair of needle nose vice grips will work. But be very careful.. pinch the hose to hard and you can tear it.. not hard enough and it wont' work... To prevent tearing them I usually put a piece of cardboard between the teeth and the hose on either side.

      note when doing this you may actually find a few leaks in the PCV system under the intake manifold. On the car I did the testing of the pressure sensor on I found a huge tear in one of his hoses.. to finish the testing I had to pinch this off with a small version of the clamps above.. it was leaking at only 1psi of pressure in the system.


      Next you will need a means of sealing off the intake and this will alos serve as the connection for the pressure source.. The simplest way to do this is with a PVC (yes PVC this time not PCV) cap from home depot/lowes. For a stock TIP or the samco TIP you can use a 2" PCV cap it will have a OD of about 2.25 and work great. Drill a hole in the middle of it, tap it and insert a air line hose fitting (the male side).. mine for example used 1/4 npt.. check the tap for the drill bit size I forget.. the best part is its plastic so if you have to go a hair smaller it will still tap just fine and the fitting will seal itself.



      For those with larger TIPs like people who made 3" ones for big turbo setups its a little more complicated.. you can either get a 3 to 2.25 silicon reducer and use the one above.. Or you can use the smaller one and put pieces of silicon hose in larger and larger sizes on it till it fits... or you can make something similar to what I did.

      The problem I ran into was that there is no cap that fits inside a piece of 3" silicon.. So I found some odd thing that was a hair larger then what I needed but very thick walled.. I then slowly ground it down on my bench grinder (if you have a lathe it would be much easier and cleaner I was covered in PVC dust) till it fit inside the silicon.. the best part about this is its not rough and bites real well. But ths one had a hole in the center so I had bought a cap for like a 1" pipe that I pressed into the center then seald with PVC cement... I then drilled and tapped the cap.

      This is the one for 3" inlets:


      ground down part:


      Once you have your fitting all made up you can attach it to a 3" hard piece with a piece of silicon.. or if you have the stock tip or samco tip just clamp it in like a map sensor.. just make sure its in good or it will blow out and possibly hit you in the face.

      Another note: Antying from this tester to the actual inlet of the turbo is not normally under boost.. so if you have any leaks in this area you do not need to worry persay.. if they are leaks that you notice at about 1psi of pressure I'd worry because they are at risk to be vacum leaks under heavy or part throttle.. this will mean that unmetered air is being taken into the car.. That annoying positive deviation code is usually caused by a small leak here.. so try and seal it up if you can... If it doesnt' leak it past like 5psi I wouldnt' worry to much about it.

      Now you will also need some sort of pressure regulator to control the amount of air in the sytem.. I happen to have gauge installed on mine which I would recommend but its only optional.. but it makes it much easier.. you can always run back and fourth and check the pressure on your boost guage. On the regulator you'll want to have a female fitting on oneside to connect to the adapter you made and a male fitting on the other to fit the airline. Some people have thought that maybe you can do this with a bike pump... wel what you need to realize is that its not all sealed up.. air is still getting passed the TB and there is gonna be at least one intake or exhaust valve open.. so the system is not entirely sealed. So you do need a good air compressor to do this.

      This is what it looks like setup:

      and apart so you can see the connections:


      Now to do the actual test.. make sure the regulator is turned all the way down not allowing any air into the system... Start by turning it till it allows a little air in but not really pressure.. you will see your stock inlet hose start to ballon up and get hard and eventually the gauge should read a lbs or two of pressure... This is where you want to search for obvious leaks while its relatively safe and not under to much pressure... Those pesky pcv leaks you;ve been looking for and cracked vacum lines will show up now.. fix those before you go any further or you will be killing yourself trying to find the real leaks because of the hissing and airflow sounds the small leaks make.

      Once you have checked all that out and fixed any leaks.. now is the time you can start turning up the pressure.. Whatever you do don't start with lots of pressure and just slap the line on the adapter or crank the pressure up real fast.. this is when the clamps fail on tht adapter and it comes flying off at your face. And remember its near your fender so if your worried about your pretty pain job put a towel on it or something.. the PVC shouldnt' damage it but the metal on the airline may. So your slowly turning up the pressure.. I like to go a few turns and then look for leaks.. go a little more check again.. There is no need to put any more pressure in it then you need.... If your having trouble holding boost because of a leak its not usually gonna suddenly go at 20psi.. its gonna be a small leak at 5psi.. little bigger at 10psi etc etc... so go slowly... If you see the adapter start to slip off the end turn down the pressure or run quickly away from the car. Try and secure the lines better.. I've found that while rolled edge clamps are better and safer for our silicon hoses for doing pressure like this you may want to pick up a beefy slotted hose clamp from the depot in the same section you got the PVC stuff from... they will allow you to clamp down much harder then the good rolled edge clamps and should help prevent it flying off.

      If you get it up to 15psi or so you are probably good.. yeah you may run more boost but like I said those leaks will probably show small signs at much lower pressures and you will find them that way.

      If you find a leak at a hose connection.. dont' just clamp down the hose where it is right then.. turn off the air pressure let it all bleed out of the system.. then loosen that clamp and make sure the silcon and the clamp are seated correctly.. there is no sense in cranking the crap out of the clamp and possibly damaging it and the silicon if its just sitting crooked.. a busted clamp or hole in the house will be a much worse leak then what you had before...


      One last reminder BE CAREFUL I am not responsible of one of you busts up your teeth or takes an eye out... and neither if vwvortex.


      edit put hardboard instead of cardboard.. that would have caused mass confusion...


      Modified by chris86vw at 1:17 PM 9-24-2004


    2. Member nebulight's Avatar
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      09-24-2004 05:13 PM #2
      AWESOME WRITE-UP

    3. 09-24-2004 05:35 PM #3
      this is a great thread

    4. 09-24-2004 05:48 PM #4
      Cool stuff, shoe me the voltage chart.

    5. 09-24-2004 05:53 PM #5
      Quote, originally posted by MRP2001GTi »
      Cool stuff, shoe me the voltage chart.

      Just search for threads I created recently.. it was only last week that I did it.


    6. Member DarkSideGTI's Avatar
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      09-24-2004 06:02 PM #6
      nice. there is a similar writeup on our local street racing board.

    7. 09-24-2004 06:07 PM #7
      Quote, originally posted by chris86vw »

      Just search for threads I created recently.. it was only last week that I did it.

      Thanks I will look, I totally missed it.


    8. 09-25-2004 11:16 PM #8
      bump so I can find it later

    9. 09-25-2004 11:30 PM #9
      this is what I am looking for, thanks

    10. Banned tim18t's Avatar
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      09-25-2004 11:39 PM #10
      got's me another project

    11. 09-26-2004 01:13 AM #11
      Quote, originally posted by tim18t »
      got's me another project

    12. 09-26-2004 12:38 PM #12
      Great write up! I've been meaning to do this for a while.

      Quick question- would the dealership have the means to do this?


    13. Banned tim18t's Avatar
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      09-26-2004 12:40 PM #13
      Quote, originally posted by SlvrBllt »
      Great write up! I've been meaning to do this for a while.

      Quick question- would the dealership have the means to do this?

      they do it virtually the same way


    14. 09-26-2004 12:42 PM #14
      Quote, originally posted by tim18t »

      they do it virtually the same way

      Cool. So now I know where to borrow the adapter since I dont have a tap set.


    15. Member IN-FLT's Avatar
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      12-07-2005 07:34 AM #15
      where the hose is resting in your intake pipe...

      get a long tie strap and put it around it and the incoming hose, that way if it decides to fly off it will limit the travel


    16. Member Mikes72sb's Avatar
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      12-07-2005 09:10 AM #16
      Great write-up I actually have all the parts in my garage, but havn't done it yet. I plan to when the weather gets warmer or I get up the guts to do this in the cold (probably the latter, I've done worse in the cold)

      ///BrooklynAutoRennen

      2014 VW GLI Autobahn/Nav/DSG - Two clutches. Two pedals. Four doors. No apologies.

    17. 12-07-2005 10:20 AM #17
      Awesome write up Chris

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      12-07-2005 10:36 AM #18
      I've personally used this method to test my intake for leaks and it proved to be extremely helpful. I found leaks that I would have never been able to find by visual inspection alone (cracked intercooler welds, leaky check valves, injector seats, throttle body gasket). The materials and tools used in this write-up should be in the tool box of every owner of a turbocharged vehicle.
      07 United Gray GTI
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      ...I am very meticulous in my inspections (vw master certified, finalist in the world service qualification championships last year).
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      walt - what are the torque specs on a vr6 head?
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      1/2" impact gun on the 3rd setting.

    19. Member Hybrid VW's Avatar
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      12-07-2005 12:07 PM #19
      Not sure exactly how well it would work for this application, but you can use some Formula 409 cleaner to help check for leaks by spraying it on a suspected leak. If there's a leak, it will create bubbles in the 409.

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      12-08-2005 12:00 AM #20
      good write up, perhaps i should give this a try

    21. 12-08-2005 03:27 AM #21
      i was wondering, what diverter valve are you using?

    22. Member autobahn1.8t's Avatar
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      12-08-2005 04:31 AM #22
      im doing this tomorrow

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      12-08-2005 12:56 PM #23
      bump for a great thread!

    24. 07-25-2007 05:00 PM #24
      Another great DIY thread with missing pictures. . Can they be fixed please? Photobucket is a pretty good place to host images.
      08 IS-F Ultrasonic Blue 11.9@120mph
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    25. 08-18-2007 06:58 PM #25
      I'd really like to see these pictures back up as well!

    26. Member 1pt8t's Avatar
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      12-11-2007 06:12 PM #26
      Do these pics still exist somewhere?

      Need VAG-COM / VCDS near So-Cal / Redondo Beach? Hit me up!
      Also have boost leak tester with PRV for 2.75-3" TIP!

    27. 03-04-2009 10:23 PM #27
      Picture's still around?

    28. Member dckeener's Avatar
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      04-27-2009 06:02 PM #28
      This seems to be happening alot now, I find a perfect diy but no pics so it's pretty much worthless.

    29. Member l88m22vette's Avatar
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      04-27-2009 06:26 PM #29
      Broken links = fail
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      07-19-2009 10:23 PM #30
      Quote, originally posted by l88m22vette »
      Broken links = fail

      x2

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      08-01-2009 02:03 PM #31
      qq this still works fine w/out pics.
      .:R32 : flickr : vimeo
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      09-14-2009 01:28 AM #32
      Hope this helps the noobs wanting pics. I can work on getting more pics when I have some time to test everything.

      You need a...

      2'' ABS Plug

      2'' ABS Female Adapter

      I needed a 1/4 pneumatic plug (what ever size or style you need, make sure you get one with a male fitting so you can tap it into the ABS plug).

      This is what everything looks like what you will have to buy. You will find all the ABS stuff in the plumbing section.




      Modified by DowNnOuTDubin at 9:31 PM 9-13-2009


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      07-20-2011 10:42 PM #33
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    34. 08-18-2011 02:47 PM #34
      Another entry in the FAQ on this topic still has pics...
      http://forums.vwvortex.com/showthread.php?2692757

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      08-31-2011 08:49 PM #35
      Did this for the first time ever tonight. Ended up finding two leaks that were making my car idle like ****: bumpy idle, engine shaking, all as the ECU/TB hunted for the optimum amount of air.

      Things to note:

      - A B&M's Baked Beans cans works great. It takes a little squeezing, but it fits perfectly in a Forge TIP... no need for a clamp.
      - If you have a big compressor, like a standup 25 gal or something, without an accurate regulator, just give it enough air until you hear the tubing pressurize. Give it slightlyyy more if you don't hear anything, but not much more. You'll blow off your tester.
      - Make sure you clamp the hose coming from the PCV port/hockey puck so you don't pressurize the crank case. If you already have done the SAI/EVAP/PCV delete, folding your catch-can-to-hockey-puck hose in half and using a pair of vice grips works great.

      I ended up having a ripped vacuum cap on one of the nipples on the underside of the intake manifold: tightened the worm clamp too much. I just put a cap that fit veryyy snug and omitted the worm clamp. We'll see how it holds up. I also had a small leak from one of the vacuum lines that goes to the bottom of the TIP near the turbo inlet. I used a screw and clamp at the open end and the screw was too small so it was leaking out. Got a bigger bolt, screwed it in and snugged the clamp down tight... voila, no more leaks!
      Last edited by erevlydeux; 09-08-2011 at 02:15 PM.

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