How do I make / buy / use / troubleshoot a boost leak tester? [merged]

[Turbo Monk3y]

All boost leak tester threads are combined here.

i read somewhere maybe the Vfaq about making or buying a boost leak tester of some sort but never found it.... the reason being my acceleration seems slower than normal and all ive done to my stock car so far is take out the air box put on a K&N filter and cut the dump tube i have my boost guage sitting in a box not hooked up yet. and since those 2 mods it when i go wot on the car i can hear the turbo spool up and it sounds nice but i can also hear a sound as my rpm increases the SHHHHHHHHHHHHHHHHHHHHHH sound does too. the sound comes from the same area as the BOV i think maybe i got a #@%#@%#@%#@% stock bov and it cant handle over 11-13 psi??? Then i shift and it makes the nice BOV sound WHOOOOSHHHH... but my car seems to be a little slower.. any ideas before i go check every tube clamp and tube????

 

[IIIISFL]

i just bought the car like 3 weeks ago its weird because it runs fine and idles great
but i do notice that the turbo doesn't generate full PSI and i lag accel from a dead stop

 

[IIIISFL]

the car is all stock besides a k&n air filter i fear a hole in the IC but if it is anything i think it is a bad clamp connection right above the IC

i dont have a MBC but i did pop out the little reducer sleeve as shown in free mod list

 

[IIIISFL]

i do have a large air compressor if i use that to preasureize the system quickly
what should be expected

 

[robs90tsi]

A bike pump should be fine, there should be no need for anything else, and if it were the MBC, he would have heard it right in front of him, not over by the IC. Do you have an aftermarket boost gauge?? Im pretty sure that you have a boost leak, whether it be a worn out upper or lower IC pipe that dry cracked and now has a hole in it, or a hole in the IC, but that could definately explain why your not reaching "full boost", what do you mean by "full boost"?? What RPM do you start to boost at?

 

[Denji]

If you dont have a boost guage, your going to have to rig something up where you can see what psi your pressurizing the i/c pipes, i dont think a tire psi guage is accurate enough at such low pressures, maybe a digital one though.

 

[IIIISFL]

when i go from a dead stop if i dont rev high before letting the clutch out
i accel slowly through about 2k to 3k RPM and then boost takes me from there
i have a stinky little stock Boost Gauge but what i mean by it doesn't boost all the way
is that when i punch it like if i go from stop and hit 2nd gear and puch hard
to redline the boost only goes about 3/4 on the gauge

 

[daren_p]

The stock boost gauge is basically useless. Get a proper aftermarket boost gauge since if you are going to mode the car at all this should be one of the first things you get. If you don't want to buy a boost gauge right now you are still going to have to get some kind of pressure gauge and rig it up to read the intake pressure while you are doing a boost leak test (drill & tap a hole in the boost leak tester cap, etc). Make sure you have a regulator on your compressor and turn it down. You don't want to connect an air hose directly from the compressor with 100+ psi on it. You don't need to test higher then 18 psi as you won't be seeing that much boost. It sounds like you have a fairly major leak so you will more then likely be able to hear it when you start to fill the intake, you will be surprised how many leaks you can find with lose clamps etc. Once you have the major leaks fixed go around with soapy water and spray it on the pipes, it will bubble where there is a small boost leak that you cannot hear.

 

[IIIISFL]

WTF a boost leak! i knew it..!


alright thanks you guys i'm sure this info will help me get this fixed
hopefully i boost better afterwards i almost went to our local track
too but it was closed due to misty rain lucky me

 

[robs90tsi]

That means that you have a crazy leak above your IC, either a hole in the IC or loose stock piping or aftermarket which ever one you have, or a hole in your piping.

Like I said, you have a leak, also known as a boost leak.

 

[IIIISFL]

HA i fixed it i used the boost leak test again and still heard it coming from the top but this time i had a friend help me and used a air compressor he applied preasure while i listened and it was leaking for sure so i took everything apart and pulled the intercooler out i couldn't find any holes by naked eye so i used the leak tester on one side and blocked off the other on the intercooler and filled it with preasure and it was leaking through two pencil lead size holes on the upper front side it almost looked like a metal plate was there or something that was held on with metal pins spot welded or something
so anyway i took out the welder and pluged each hole with a welding rod cause thay fit in the small holes then patch welded the two spots after fixing i tested the intercooler to see if it would hold preasure and it did i tested up to 30PSI i figured thats plunty since if i am going to run anything more then that it wont be on that stock POS
as i go to bolt it back in i find a mount that had broken off that was what broke and left two holes behind it looked like the previous owner could have hit a parking spot stopper
or something to bump the intercooler and break the mount on top the mount was not held on good at all! two small pins and spot welds at most and this is like the main mount


if you have the same problem as i just had be sure to consider this the mount i am talking about if your are facing your car head on the intercooler is below the left headlight the mount is right behind the headlight and just below your intake filter


thanks everybody for fast help couldn't have done it without the info

 

[TurboFever]

ok so I made my own boost leak tester but I dont think its working. Its kind of larger than normal, but when I stuck it in my car and pressed air in I dont hear anything leaking. I used a large air compressor, I was scared it was going to blow something because I cant regulate how much air I put in there so I only left it on for a few seconds but still no air escaping? Now my car runs worse my turbo spools but I dont feel it power. Should I just buy a prefabricated leak tester, and boost gauge?

 

[ChicksDigBoost]

Definitely get boost gauge, it should be the first mod to any turbo dsm. If you have a boost gague you can see what psi your pressurizing the system to.

 

[kenamond]

Look in the classifieds for a leak tester. It may be sealing just fine, but you have a very bad boost leak. Definitely get a boost gauge, though, before you blow your turbo seals by accident.

Did you make your tester from pvc and a rubber coupler with a tire valve in the end cap? If so, get another pvc end cap (without the hole), and clamp the other end onto this other cap. Then you can put some pressure into it and see if it holds. My fist tester didn't seal around the valve, so I designed my own variant which holds great.

What diameter is the coupler? I used 2.5" coupler in my leak tester for my B28 which has a 2.25" compressor inlet (same as stock T25). If you got one much bigger than that, you might have problems clamping it onto the compressor inlet without leaking.

 

[TurboFever]

Look in the classifieds for a leak tester. It may be sealing just fine, but you have a very bad boost leak. Definitely get a boost gauge, though, before you blow your turbo seals by accident.

Did you make your tester from pvc and a rubber coupler with a tire valve in the end cap? If so, get another pvc end cap (without the hole), and clamp the other end onto this other cap. Then you can put some pressure into it and see if it holds. My fist tester didn't seal around the valve, so I designed my own variant which holds great.

What diameter is the coupler? I used 2.5" coupler in my leak tester for my B28 which has a 2.25" compressor inlet (same as stock T25). If you got one much bigger than that, you might have problems clamping it onto the compressor inlet without leaking.

Thanks for the reply. Yes I just ordered a boost guage dont know how long until it arrives. But as far as the tester I had to buy a 3" to 2.5" rubber tube from autozone that is for intakes because there largest hose size was only 2". So my pvc pipe is 2.5" i.d. But it doesnt sound like any air is escaping from there and the clamps were very tight. I did notice some slight oil in my intake pipe.

 

[FORMONTOYA]

I was scared it was going to blow something because I cant regulate how much air I put in there so I only left it on for a few seconds

You also need some way to regulate the air coming out of the compressor. The max UNREGULATED pressure of my compressor is 115psi. If I shot that into my intake track, even for a second, it would more than likely blow every seal and coupling in the system. Don't shoot more than about 5psi or so over the boost pressure you plan on running and you'll be fine.

 

[TurboFever]

You also need some way to regulate the air coming out of the compressor. The max UNREGULATED pressure of my compressor is 115psi. If I shot that into my intake track, even for a second, it would more than likely blow every seal and coupling in the system. Don't shoot more than about 5psi or so over the boost pressure you plan on running and you'll be fine.

My compressor is about the same. How will I know if I blow a seal or coupling system??

 

[FORMONTOYA]

My compressor is about the same. How will I know if I blow a seal or coupling system??

First off get a regulator for your compressor. They can be found just about anywhere that sells compressors, and they range from cheap to expensive, take your pick. Then set your regulator to about 5psi or so higher than your target boost pressure. Hit the intake track with air and start spraying every connection on the intake track with soapy water, if it's leaking, it will bubble up on you. Then just fix the leaks. Most likely the throttle body shaft seals and BISS screw o-ring will be a big leak if they haven't been changed in a while, and also the gasket for the BOV is another common leak point, of course the couplings also. Injector seals, PCV valve, etc.

I usually do my boost leak test from the inlet to the inter cooler as more than likely the turbo seals will leak without oil pressure behind them to help seal even on a brand new turbo.

 

[kenamond]

Those boost leak testers aren't going to flow too much air even at 115psi (tire valves don't flow a huge amount of air), so it'll take a second or two to pressurize it, but you DEFINITELY need a boost gauge to know what you're pressurizing your intake to. You can add spurts of air at a time and have someone monitor your boost and keep you posted (if you can't see your boost gauge from in front of the car). Until you get a regulator, just be EXTREMELY careful. If you have big leaks, you may not be able to get any pressure to hold. A bad PCV will leak very quickly, but it's very easy to diagnose (unscrew it from your valve cover and see if air leaks through it - it shouldn't). TB gaskets, bad PCV, holes in your IC, cracked hoses/vac lines, leaking couplers, injector insulators, BISS, TB shaft seals, BOV, and intake/head gasket are where you'll have leaks. Find as many as you can before you fix them, or you might fix one and have to rip that part off again to fix another you find later and reintroduce a leak in the process.

 

[FORMONTOYA]

Those boost leak testers aren't going to flow too much air even at 115psi (tire valves don't flow a huge amount of air)

I will agree that the tire valve doesn't flow a lot of air, however, the intake track is not very big and it will fill up fast once he starts getting the leaks fixed, and shooting 100psi + into a system that isn't designed to hold anywhere near that pressure is asking for trouble. Who's to say how many seconds it will take to over-pressurize the system to the point that things start flying apart. If someone has ever over-pressurized something to the point that it explodes they will know that shrapnel randomly flying around can create serious personal and property damage. Using higher pressure on any system that isn't designed for it IS hazardous and maybe my statement might be construed as a "scare tactic", however, sometimes that's what needed to help someone work in a safer manner. You should never pinch money when it come to your safety, nor should you run a compressor without some kind of regulator unless you want to ask for trouble at some point.


Get a regulator (even a cheap one) for your compressor and set it for about 5psi or so above what you would run as boost pressure. The safer you work, the better your body will work when the job is done.

 

[FORMONTOYA]

I did see that in your post. I have also seen people during my life that disregarded the safety precautions and decided to be EXTREMELY careful instead that ended up in the hospital. Sometimes sh!t happens beyond your control, no use pushing it.

Everyone has their own opinion as to how to get the job done, I just personally like my appendages attached and not laying around loose on the ground. Not trying to be an a$$, but I am an a$$ when it comes to my own personal/property safety.

 

[TurboFever]

I dont know if I mentioned it before but after my initial boost leak test my car ran worse. And there was also a pop or two as I took it for a test drive. Theres no smoke or anything and it looke fine but rides crappy. I very barely even boost. My car is now really sluggish. I dont feel like waiting for the boost guage to come so I am going to go pick up a regulator and do another boost leak test. But is there a chance that I already screwed something up?

 

[FORMONTOYA]

I doubt that you "seriously screwed something up". What probably happened is that you just blew out the rubber seals even worse than they already were. Although you will have to verify that during your next test. The worst spot to leak from with an initial boost leak test is the throttle body seals (rubber) and the BISS screw o-ring (also rubber) and then the BOV gasket (paper composite).

More than likely the seals are even more "blown" than they were before you started. Which would account for the poor performance. I would definitely stay out of the boost as much as possible until you get it resolved as all you're doing with big leaks is over working the turbo. You'll also run richer than normal because you will suck in unmetered air, which if rich enough, would cause a stumbling or popping during idle, between shifts, or deceleration.

 

[pitbullowner_2]

just thought i might add this there is a boost leak tester on ebay that the guy said he used and blew 30 psi through it and it didnt leak at all for $18 shipped

 

[kenamond]

just thought i might add this there is a boost leak tester on ebay that the guy said he used and blew 30 psi through it and it didnt leak at all for $18 shipped

Make sure it's the correct diameter for your compressor inlet before you buy it. Sounds like a fair price. Building your own will cost you less than half of that, but it's not necessarily as easy to build one yourself as the tech articles out there say if you don't have access to great hardware stores with all of the pieces you need.

 

[TurboFever]

Ok so I did the boost leak test earlier, my results were; so far two noticeable leaks. One was coming from a screw on the throttle body im guess thats the BISS screw, and there was another leak I couldnt really tell where it was coming from. It would start to hiss a second or two after the BISS screw would bubble up, it was coming from the back near where the injectors, intake manifold and spark plug wires are. I put my ear and can hear where its coming from but I dont see no bubbles or anything. It sounds like its coming from an injector (3rd one left to right)? could that be right or is there something else in that area?