Check for boost leak?

[CrazyUglyCoyote]

What is the easiest way to check for a boost leak? I really dont want t buy a gaoge tool, so is it acceptable to just pour soapy water over my pipes, and see where is starts bubbling? (Little thing I do to find holes in tires )

 

[1fast97gsx]

http://www.vfaq.com/mods/ICtester.html

Make the damn tester ... it costs like $10.

 

[POlarSource]

I made the same thing. It works wonders. I now find myself fixing everyones boost leaks now though

I ended up getting the thing for practicaly nothing. I only paid for the end cap... Everything else I got them to give me for free.

 

[boostnmt]

deffinately make a boost leak tester, well worth the ten dollars it takes to make one. I thought I could do without one but now I realize they are a great tool to have whenever you're in doubt that your car might have a boost leak.

-Travis

 

[oldman]

so is it acceptable to just pour soapy water over my pipes, and see where is starts bubbling? (Little thing I do to find holes in tires )

How will it bubble without pressure air inside?

 

[CrazyUglyCoyote]

I thought I could start it up, and boost a little.

 

[power=dsm]

how do you guys pressurise your system?? with a tire pump??

 

[LA97GST]

I tryed to use a tire pump and really couldn't tell what was happening. A compressor would be tooooo loud eh? I dunno

 

[POlarSource]

I have used a tire pump when I am really desprate.

I have a compressor at my house that is freaking huge... The thing bearly ever turns on. I was thinking those portable air tanks that you pressurize with a compressor would work really well. Its enough to pressurize the system atleast a dozen times and there is no noise... They are about the same size as a propane tank for the bbq.

Oh, I have also used the compressor at a gas station once... That was haggerd.. But it worked

Just some ideas

 

[tsibryan]

Don't want to jack the thread, but I've made my own thread before and couldn't get any helpful replies. When I tried the tester I couldn't get my car to hold hardly any pressure. I think the most I got up to was about 7psi, and the only leak I heard was right around the turbo. I sprayed soapy water there and found nothing, and everyone on here started telling me to put the engine at TDC. Does that make any difference? The vFaq doesn't say anything about that. Thanks for any help.

 

[CrazyUglyCoyote]

Don't want to jack the thread, but I've made my own thread before and couldn't get any helpful replies.

Thats because people like me more! But that's OK, because Ive got enough love for the whole world! Except for the french! Grrrrrrrrrr! Only half love for them.

 

[zachakagoat]

Build the tester, throw it on the intake side of the turbo, make sure if you have a manual boost controller that you block the intake side of that too. Definately use a compressor if you can get access to one, go to a shop most of them will allow you to borrow it for a second because air is free they don't really care. You will DEFINATLEY hear a leak if it is there, sounds like a ballon leaking air. If you hear it coming from a general area like the throttle body then spray some soapy water or WD40 on there to try and figure out where it is coming from. There are only a few places on the intercooler piping that could be leaking so just tighten down all of the hoses to be safe. I try and do this test every month or so atleast just to make sure that nothing came loose because the leak will mess up your tuning if you are doing any. Good luck man it comes natural after a few times

 

[oldman]

the only leak I heard was right around the turbo. I sprayed soapy water there and found nothing,

Open your oil cap during next test and listen for hissing sound. Your turbo seal might be in question.

 

[tsibryan]

Is the turbo seal between the hot and cold sides of the turbo? The cartridge?

 

[oldman]

Is the turbo seal between the hot and cold sides of the turbo? The cartridge?

Yes, it keeps oil and coolant inside the center cartridge. If you have a bad turbo seal, pressure air can leak from the seal through the oil return line to your crank case. I'm not saying you have bad seals, just giving you ideas since you said the leak is right around the turbo area.

 

[steve]

everyone on here started telling me to put the engine at TDC. Does that make any difference?

That's the last place you want your engine to be at when pressure testing the intake. Air will go right past the intake and exhaust valves on cylinder 4 and out the exhaust pipe. You want the engine to be somewhere between 210 - 30 degrees before or 30 - 150 degrees after TDC so that no cylinder is in overlap where both set of valves are open.

Steve

 

[cool_g_83]

Tdc?

 

[CrazyUglyCoyote]

TDC= Top Dead Center...... unless there is another meaning for it. #1 piston at the top right?

 

[steve]

TDC= Top Dead Center...... #1 piston at the top right?

Yes. We are usually talking about TDC compression stoke when we say TDC since the piston goes through the top of it's travel twice in a cycle, In our engines both 1 and 4 are in phase and 2 and 3 are 180 out. So when 1 is at TDC compression stoke, 4 is TDC exhaust stroke, 2 and 3 are at the bottom of their respective strokes.

Since cool_g_83 didn't know what TDC was I guess I should define overlap. During the end of the exhaust stroke and the beginning of intake stroke both the exhaust and intake valves are open. That time when both are open is called overlap.

Steve

 

[2GeNTSi]

Agh I need to do this...it's so simple but I never took the time to actually try it out. I've checked so many things and I even just threw in a 14b and it LAGS, with my mods it shouldn't be lagging as much as it is.

One question though, if I had a boost leak wouldn't the boost gauge be off? When I still had the T25 my boost gauge read fine so I figured I never had a leak (-20hg when warm...about 12-14psi at WOT with no MBC). Since I put the 14b on though, it'll say I'm at 6psi but I can't even hear anything spooling up and it doesn't feel like it's building boost where as with the T25 the spooling was very loud and you could actually feel something at least. The exhaust housing near the flapper did have some cracks but they weren't bad...bah anyways I'll end it here, I'm starting to rant.

 

[Fifty]

when i shift at 3.2rpm when the turbo starts to spool i hear the BOV the loudest but any point beyond that it is softer am i leaking? also i onlu heard the bov when i am accerating as in the rpm is climbing when i am coasting like at 3-4rpm i dont heard it when i step on the clutch.

anyone have an extra boost leak tester?

 

[steve]

If I had a boost leak wouldn't the boost gauge be off?

Why would it be off? It's going to read what it measures. If your turbo is able to push enough air to pressurize the intake with the leak, it will. Your just making the turbo work harder than it needs to and injecting fuel for air that never reaches the cylinders.

Steve

 

[2GeNTSi]

Why would it be off? It's going to read what it measures. If your turbo is able to push enough air to pressurize the intake with the leak, it will. Your just making the turbo work harder than it needs to and injecting fuel for air that never reaches the cylinders.

Steve

Oh what I meant was that the reading would be lower because the air is leaking out. My gauge reads about 14psi at WOT all the way to 6k. I was just curious because I thought maybe somehow even though I had a leak, the gauge would still read 14psi.

Today one the way to the bank I punched my car in 2nd gear just a bit before it was at operating temp. It started building boost and was pulling more than usual, but then it hit fuel cut. Then after I left the bank, I decided to test it out again but from 1st. Punched it and it went all the way to 6k keeping 14psi steady, all the way through 2nd as well. I then made a u-turn and did the same with no fuel cut so I'm not sure what's going on. Maybe it was the fact that my car wasn't fully warmed up (but it's pretty warm outside probably about 75F) or maybe I do have a small leak.

 

[steve]

Oh what I meant was that the reading would be lower because the air is leaking out. My gauge reads about 14psi at WOT all the way to 6k. I was just curious because I thought maybe somehow even though I had a leak, the gauge would still read 14psi.

I knew what you ment, but I wanted you to think about it. I'm not sure that you have yet, because what you thought is correct but your unsure as to why.

The gauge won't start dropping due to a leak until your turbo can't push enough air to keep up with the leak. Since the wastegate won't open until the boost pressure is reached it will continue sucking air past the MAF, where it's metered, and compressing it until the pressure reaches the set point for your MBC and then the wastegate will open.

If air is leaking the turbo has to work harder to reach the pressure where the wastegate opens. Perhaps working as hard as it would if you had set the MBC to 18 or more psi to get that 16 psi built up.

Since the air is metered anything leaking lowers the effective fuel cut trigger in the ECU because your counting air you don't actually use.

Steve

 

[oldman]

Like steve have already said, the boost gauge measures the manifold pressure with or without leaks therefore it's the correct reading. What changed is that ecu is injecting fuel for the missing air and you're overworking (over spinning) the turbo in order to maintain the desired or measured pressure in the intake tract. I have seen too many overspun their turbo doing WOT runs with major boost leaks. My suggestion to you is to ease off the throttle until a complete boost leak test is performed as I suspect you have more than just a small leak. Unless of course money isn't an issue.