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????

 

[WeaselHack]

To answer your question...YES 16 pounds is sufficent for detecting leaks. If you DO have a leak the actual pressure in your intake will be below the 16 psi that you set at your regulator. You can safely increase the pressire to 20-25 lbs to make sure you found all the leaks. Good luck!

 

[TurboDreamzGST]

thank you all....see i was just worried about setting the output pressure at say 20 psi and leaving it continuously pushing 20 psi into the intake system and have it continuously build up higher than 20 psi....do you think this will happen because if thats the case ill just fill up my intake system to about 20 psi like you suggested and when it seems to get to that point on the boost gauge ill just set the output on the compressor to 0 so it will keep the intake system pressurized and i can check for the leaks without worrying about the intake system getting too much pressure.....does this sound like a better idea?

 

[dsmclipse97]

If you dont have someone watching the boost gauge your playing with fire. You could accidentaly make a REALLY BIG hole if you overpressurize.

 

[blackbyrd]

If the regulator is at 20psi, the end of your hose is only seeing 20psi-ish. I dont think you could pressurize more then 20psi. You should have equal pressure. It's always good practice to watch the boost gauge or put one on your tester though.

 

[TurboDreamzGST]

ok i thought the same as you blackbyrd.....i'm def. going to have someone watching the gauge but i just wanted to go through all the steps before i did it because this is my first time doing it and i don't want to cause more problems....thanks everyone for their help and any further suggestions are still appreciated...i'll let you guys know how i make out with the test

 

[FORMONTOYA]

Do not perform the test without a regulator on the compressor. The average air compressor will put out around 120PSI of air (your compressor is higher). The intake track is fairly small and will fill up rather quickly, even with someone watching, possibly blowing seals and couplers that where otherwise fine.

Get a regulator if you don't have one already and set it at roughly 5PSI higher than your max boost pressure so you have a "safety" margin.

I run 20PSI on my car and test to 25PSI. Obviously the regulator is set at 25PSI for tests.

 

[eclipsegsx1736]

I just set the regulator on mine to 60 or so and fill it until it hits 25 psi on my gauge (or whatever you're testing to). My compressor takes ages to hit 25 psi unless the regulator is set well above that.

 

[steve-o_95_GST]

http://web.archive.org/web/20020808004211/http://www.dsmgrrrl.com/FAQs/leakdown.htm

 

[hewhoisknot]

As everyone else has shown you, you need a leak down test to test for internal things. The boost leak test will only test things up to your TB.

BUN

 

[oldman]

As everyone else has shown you, you need a leak down test to test for internal things. The boost leak test will only test things up to your TB.

BUN

Not exactly. Boost leak test will test up to the intake valves and depending on the positioning of the valvetrain, pressure air will enter at leat one combustion chamber.

 

[dvbrien]

Not exactly. Boost leak test will test up to the intake valves and depending on the positioning of the valvetrain, pressure air will enter at leat one combustion chamber.

Does the throttle body not seal completely from the angle of the "butterfly"? If not I suppose depending on the duration of the cam, there is a moment when both intake and exhaust valves are open... if the throttle body does not stop the pressurized air from entering the intake, how is it kept from escaping into the exhaust through the combustion chamber?

What is letting the pressure build in the intake system?

 

[elfroggo]

THe throttle body is not a complete seal. I did a boost leak today and one of the injector seals was leaking.

The is a small chance that one of your cylinders could have intake and exhaust valves open at the same time but otherwise either intake or exhaust valves are closed so the intake tract can build pressure.

 

[oldman]

Does the throttle body not seal completely from the angle of the "butterfly"?

If it's a complete seal, it would be pretty hard to keep the car running at idle wouldn't it?

If not I suppose depending on the duration of the cam, there is a moment when both intake and exhaust valves are open... if the throttle body does not stop the pressurized air from entering the intake, how is it kept from escaping into the exhaust through the combustion chamber?

Valve overlap happens at the end of exhaust and beginning of intake stroke, it's said that 30* before or after TDC will avoid valve overlap. This is also why listening to your tailpipe is also one of the standard procedures during a boost leak test, pressure out of exhaust usually implies defective EGR, trashed intake and exhaust valve stem seals or you're at or near TDC of any cylinder (valve overlap).

 

[95blackGsTurbo]

The TB will hold it for a while but it will slowly leak by. I just rotate the motor to line up the cams at TDC so all the valves are closed and I do a pre TB test and then open the plate and test again.

 

[oldman]

Not necessary to be condescending...

Aren't we a little sensitive? If it came off that way, my bad.

The TB will hold it for a while but it will slowly leak by. I just rotate the motor to line up the cams at TDC so all the valves are closed and I do a pre TB test and then open the plate and test again.

1. The combination BISS, ISC and around the plate itself is much larger than the little valve on you leak tester, there will be no delay and the need to test with plate open. Don't you test while watching the boost gauge which is tapped after the TB? Am I being condescending again?

2. TDC is the worse place to be because it ensures valve overlap in the corresponding cylinder (1/4, 2/3), see my explanation up top.

 

[DSM-Talon-John]

Ok well during my test the bov lets all the air out, i didnt think it was supppose to do that, you can see that its barely open and each pump the air just exits that, i screwed the bolt down so it wasnt open and the air still came out of it there. When i gave it gas with it screwed down it doesnt move up at all. Is my bov just bad? If its not a problem how do i block it off? Also will a stock 1g fit onto a greddy rs ready ic pipe?

 

[turbo98eclipse]

what kind of bov is it?

 

[DSM-Talon-John]

greddy rs

 

[Wells]

Can you make the bov any tighter? It's not supposed to leak out air like that.

 

[2gAWDTalon]

I also have a Greddy and I had to put some gasket sealer around the screw on the top. Is that where it is leaking?

 

[DSM-Talon-John]

No when i take the recirc tube off and pump it up the air comes out of there, i tightened it up and it still did it. It was tightened to where you couldnt see it open anymore, its only open a tad though. When you give it gas it doent move at all either.

 

[Wells]

Keep on tightening it until you don't feel air coming out .. and if that doesn't work then it may be bad. I had a friend that bought an ebay knock off, then later replaced it with a used greddy type-s one. The greddy one leaked, so he took the top of the greddy one and replaced it with the knock off one, and it works fine. So basically, it may have just gone bad.

 

[DSM-Talon-John]

ha, thats exactly what i did. Ill figure something out the car runs fine right now or so i think.

 

[Dan97gst]

I just did a boost leak test and for some reason this time it made a oil bubbling noise when under boost. Kind of like the oil was dropping back down, and also it was leaking air out the line that comes out of the left side of the valve cover into the intake. Is this a normal thing, because the last time I did the test I don't remember this happening.

Thanks
Dan

 

[Gamble97]

If it was leaking air then you have a leak there. What psi were you at?