DIY: Boost Leak Tester

[Dave926]

Its pretty regular here that there are so many threads with cars that have running issues, most of the time due to vac leaks that are not easily found. Ive build one here with input from other automotive forums. Its simple, cost very little money and works MINT!


Parts List

Spray Bottle
You can get this anywhere for about $2. Doesnt even matter so long as it can be adjusted from a mist to a stream


Your favorite household dish soap


3" PVC cleanout plug
Buy Here


Slime Tire Valve .453"
Buy Here


Drill bit 5/16th's (Use whatever style you want, I didnt have one)
Buy Here


3"x3" Rubber Coupling, adjust one end to the size to match your Turbo Inlet/MAF. MEASURE DO NOT ASSUME SIZE
Buy Here


Loctite Epoxy (May not be necessary)
Buy Here


Air Chuck w/Locking Clip (makes this MUCH easier) You need a fitting to mate this to your air hose, you MUST use teflon tape to seal it.
Buy Here


Process/Assembly

Using your 5/16th drill bit, bore a hole in the center of the square part on the PVC clean out plug. The hole will be a bit smaller than the .453" hole needed for the tire valve, so wiggle the drill around a bit while its on to enlarge the hole slightly.

Before you jam the tire stem in, make sure you have the orientation correct for your engine bay. There is no right or wrong way to do this here.

Keep doing this until the tire stem goes in. It will be a struggle which is good, it means it will be airtight. Getting this to go in the hole is akin to putting o-rings on a cis injector.

Finished Product



At this point use the epoxy if you like, mine was so tight there is no chance air is leaking out. Just be careful where you apply it, do not fill the valve with glue or air cannot pass through.

Assemble with the rubber coupling, crank those worm gear clamps for all they are worth

Finished Product



Get the Air Chuck with the clip.




Make sure your compressor/tank has a regulator on it, adjust till its down to a reasonable psi. Nothing crazy here, but setting it to 5 psi would be useless. Regulated pressure on the left (red knob to adjust), tank pressure on the right.


How to Use It

Mix water with a nice portion of dish soap in the spray bottle, test the spray pattern. Adjust how you like it, but I think its best used when it makes a stream.

Attach the coupler to your turbo inlet/maf, again make sure its very TIGHT.


Hook the air chuck to the tire stem, and spray away where ever you think there is a leak. The soap will bubble like mad even with the smallest leak.

Quick solutions for fixing vac/pressure leaks

Cheap Hairspray on the intercooler pipes


Home Made bead roller, exhaust piece from a clamp welded on one side, steel washer on the other


Zip Ties for Small vac lines


Mods put this in the FI FAQ, since there is nothing there for boost leak detection devices.

[VDub Dan-O]

Back when I had my S4, I didn't use the tire valve and just drilled and epoxied in an quick connect air fitting straight into the PVC cap.
One less thing to blow off and hit you in the face. (ask me how I know)

Love the homemade bead roller.
I'm going to make one of those!

[Dave926]

That would work. The clip on air fitting is nice, Ive tested mine to 30 psi no problem yet. Then again if it popped off the only thing it would hit is my strut tower

The tire valve is fed from behind and pressure seals it, the epoxy is just there incase someone drills the hole too big.

The bead roller is something Ive seen on other forums, its not mine unfortunately.

[vwturbofox]

nice i built mine from 2 1/2 exhaust pipe welded a flat piece of metal then welded a quick connect air fitting all was free parts laying around from other projects helped find tons of leaks.

[Dave926]

Not bad to be honest. I dont think I could weld good enough to prevent leaks lol.

[matt_bogner]

you don't want to be pressure testing your CAC system through the turbo. if you pressurize it through the inlet side:

1. you could spin your turbo at high rpm without any oil flow to the bearings/bushings.
2. you can damage the bushings/bearings and allow oil to pass through either side of the turbo, unless it is a properly designed compound turbo system (see CAT ACERT engines)

the proper way is to remove the pipe from the compressor side of the turbo and pressure test the system that way. if you are just testing the air-air or intercooler the standard is you are allowed to loose 5psi over 15 seconds using no more than 30 psi (which i don't understand some systems run over 50psi). be safe when using homemade tools, 30 psi is a lot of pressure. the last thing you want to happen is have your hard plastic tool fly off and hit you in the nuts.

[Dave926]

I will take your advice, but spinning the turbo seems silly.

If you have a large enough leak I could see that happening, but otherwise i doubt it. Leaks can happen at the compressor outlet, or even where the compressor housing meets the CHRA, so testing that with the pressure tester on the discharge hose will not work.

The hard plastic tool cant hit me in the nuts anyways, the strut tower would block it.

If a turbo cant handle 30 psi it isnt for me

[matt_bogner]

I will take your advice, but spinning the turbo seems silly.

If you have a large enough leak I could see that happening, but otherwise i doubt it. Leaks can happen at the compressor outlet, or even where the compressor housing meets the CHRA, so testing that with the pressure tester on the discharge hose will not work.

The hard plastic tool cant hit me in the nuts anyways, the strut tower would block it.

If a turbo cant handle 30 psi it isnt for me

think what you will, but it is no different than running your engine without oil.

as for pressure testing through the turbo and finding a leak @ the turbo. you will probably visually find the turbo is pretty damaged for it to be leaking and being able to notice a boost leak, if it is not damaged the likely outcome here will probably high crankcase pressure causing blow-by which is not all that common, but it does happen from time to time.

if you still think i'm wrong i'll post up the procedures from CAT and Cummins on testing for boost leaks. they know a thing or two about boosted engines. neither mention testing through the inlet side of the turbo(s)

the majority of leaks that i have found have been at hose joints, typically from using the wrong clamps or not having and kind of bead rolled into the pipe. intake manifold leaks are also pretty common (blown gaskets, warped flanges etc...)

[Dave926]

No Im talking about the turbo spinning while using this boost leak tester. My turbo has yes to spin while doing this, and I think the only way for it to spin would be if I had a pretty decent leak such as a tube not being attached.

[GinsterMan98]

I agree, it will not spin if there is no flow. a leak will not cause it to spin IMO. I get what your saying though. Nice tester BTW.

[Dave926]

Thank you. Id like one of the mods to put this in the FAQ because there is nothing in there to build a boost leak tester. I think in total I spent 25 bucks or so to build this, and I had to but everything shown because I did not have the tools.

[VDub Dan-O]

if you still think i'm wrong i'll post up the procedures from CAT and Cummins on testing for boost leaks. they know a thing or two about boosted engines. neither mention testing through the inlet side of the turbo(s)

I'll bite, I'd be interested in seeing that information.

I would think on a big dog/big displacement diesel there's enough air flow as the CAC and all the tubing fills up with air to spin the turbo over. On our little pup sized 1.8 liter engines I just can't see where there's enough airflow to spin the impeller and cause damage you speak of.
If this was the case, every time we shut out engines off with no oil pressure we would do the same catastrophic damage you speak of.

Plus as stated before, VW Audi guys have been boost leak checking this way for years.

[GinsterMan98]

if you still think i'm wrong i'll post up the procedures from CAT and Cummins on testing for boost leaks. they know a thing or two about boosted engines. neither mention testing through the inlet side of the turbo(s)

I don't want you to get mad so just hear me out on this one. If you have a leak in the cold side housing of the turbo the only way to find it is to test the cold side of the turbo. I would just cap off the outlet and put a home made pressure testing thingy on the inlet of the turbo and see if it leaks. It will not spin if there is no flow, it does not matter how many psi are in there, if there is no flow the turbo will not spin. If you just pump air unrestricted though it then I can see your point and it would spin. A small leak will not cause enough flow I would think. Please don't take this the wrong way and get mad, I am just saying what I think about this. You would want to be careful with how much pressure you use to test it though, I would only use enough to cover how much boost you are running.
I am not an expert on turbos so If anyone knows thats this method could damage the oil seal or something, please share. I have done this a few times on diffrent cars without negitive side effects. If its wrong then its wrong, I just don't see it spinning the turbo and damaging the bearings that way.

[Scrubbs]

Although i dont believe a spining turbo will do much damage, but think what happens when you put 30 psi in , and it blows the connection off. im sure the turbo will spin quite fast. done it with a couple old stock turbos going back for cores.

[Dave926]

Although i dont believe a spining turbo will do much damage, but think what happens when you put 30 psi in , and it blows the connection off. im sure the turbo will spin quite fast. done it with a couple old stock turbos going back for cores.

Unless you were using zipties to hold the tubing on, it shouldnt blow right off. Maybe I should add to progressively increase the pressure until a reasonable amount while searching for leaks?

[masterqaz]

Highly unlikely that spinning up a turbo briefly without an oil feed would do any damage. Hardly any load or heat to cause the bearings or journal bushings to sustain damage or fail.

After all oil is quite viscous and doesn't just disappear when the engine isnt running.

What you know was written by someone as insurance, so you couldnt blame them as technically you did it wrong by their standards.

Old I know.

[SuperchargedK20Z3]

Where do I hook this up at to test my entire system intercooler, piping, turbo, and all?

I have an 09 tsi gti


Sent from my DROIDX using Tapatalk 2

[Dave926]

I would say disconnect the airbox, and go from there. If i remember correctly the inlet pipe on a tsi is plastic, so be caref

[masterqaz]

Where do I hook this up at to test my entire system intercooler, piping, turbo, and all?

I have an 09 tsi gti


Sent from my DROIDX using Tapatalk 2

Safest bet is directly to the turbo inlet. Which means removing the inlet pipe.

[groggory]

FAQ'd in 1.8t FAQ

[Ronnie@JDLAutoDesign]

I built one out of some scrap aluminum we had at the shop. Also used an air pressure regulator, vacuum hose, and a few dif size couplers depending on turbo inlet size

[groggory]

I built one out of some scrap aluminum we had at the shop. Also used an air pressure regulator, vacuum hose, and a few dif size couplers depending on turbo inlet size

Sounds like my personal setup. Plenty of adapters for any inlet size