Car not holding pressure during boost leak test

[SpoolinGSX]

I tried a boost leak test using the tester from vfaq. I tried it at both the turbo inlet and the throttle body elbow. Weither i use a compressor or a bike pump the car just wont hold any pressure. It reads about 2 psi if even on my boost gauge. I have most of the left side of my engine bay taken apart for a clutch swap and i havnt noticed any large holes in hoses or any components. There is a empty nipple on the farthest right on the charcoal canister, but i highly doubt that could be my prob. Any ideas as to what i could do or what may be wrong?

 

[sunflashx]

Get a spray bottle and fill it with soapy water. Dish soap works well.

Spray it on all your connections and start looking for bubbles.

 

[nine5raptor]

If it won't even hold 2psi you should definatly be able to hear the leak. Is it quiet when you are doing the leak test?

 

[bjgarvin]

i don't understand how people don't understand the concept of this. i have reprinted this post from another thread with my own permission. and i added some stuff.

the valve stem style testers are garbage. make one with a male quick release air fitting that will hook up directly to your compressor's air hose.

hook up a compressor with an integral tank to the tester that is connected to the turbo inlet. using the regulator on the compressor, turn up the pressure to 20psi. listen for leaks. fix accordingly.

i know most of you out there don't own a compressor of this type, but somebody out there does. be nice, make friends and buy them a beer for letting your car leak oil in their driveway while you do this.

if you are testing for a leak for the first time, chances are you have one and you won't be able to "pressurize" the intake. with decent size leaks you need a significant and constant amount of airflow through the intake tract. somtimes you only hear leaks at 20psi that you couldn't hear at 15.

if the tester is not tight enough on the inlet it will blow off with alot of force. keep it in mind.

the tank is key so you can hear the leak without the compressor running. get it?

Ben

 

[Rob_DSM]

That is some good info. I'm going to have to put one of those together this weekend. I installed a Dejon upper S-pipe to my L-pipe and now I have a horrible boost leak. Anything over about 1 or 2 psi I get a really loud whistle. It sucks having to baby it around the last couple days.

 

[ViciousVendetta]

I did the same thing recently. It would only go up to a couple psi and leak out pretty damn fast, but I could definetly hear the noise. After replacing 20+ vacuum lines, many with large cuts / holes in them, I found my throttle body to have a large amount of air leaking. I just put some rtv on the gasket, hoping I get more than 8.5 psi tomorrow!

 

[mitsuspeed]

Originally posted by nine5raptor
If it won't even hold 2psi you should definatly be able to hear the leak. Is it quiet when you are doing the leak test?

agreed. try using a spare (clean ) piece of vacume line as a stephiscope if your having trouble.

 

[DSMJim]

Here is my boost leak tester. Used a quick fitting for my air compressor. Just regulate the air via the valve. Works really well. The only parts you cant get at home depot is the silicone hose. I made it in 2.5 inch and put a piece of 2.25 silicone inside it so it will do both size pipes.

 

[nine5raptor]

you did this, Jim, but for the others, when you put it all together, use a decent epoxy on all the connections where rubber meets plastic or metal meets plastic. It would suck to shoot out that plastic cap or even the quick-connect using 25+ psi I test my system to at least 20, usually 25, to find the small leaks.

 

[bjgarvin]

quite the ghetto rig there Jim , but yeah, that's the idea.

Ben

 

[nine5raptor]

I think mine looks even worse
But, hey, as long as it is functional, it has a certain beauty about it

 

[DSMJim]

She dont leak but my intercooler pipes did. Wow, talk about leaks at every connection. One was so bad that It was blowing air out like hair dryer. They are all fixed how so the car should go a lot better.

Highly recommend this to anybody who has not done it. If you think your car doens't have boost leaks think again. I re-did all my pipes when I installed my FMIC and thought it would be fine. So much for that thoery..

 

[nine5raptor]

When I redid mine for blowthrough. I had the problem of: pressurize the intake, start to listen for leaks, pipe blows off, I wet myself (they are kinda loud when your ear is right next to it ) and start over.

I used a lot of JB Weld to stop that.

btw. how hard is it to get jbweld back off? I have access to a mig welder now and will probably make more permanent beads.

 

[bjgarvin]

i hear you.

the short RC 550's were a puzzling mess of leaks for a long time. and then there is the obligatory hunt for the MBC leak that isn't there. that only happened twice... ok, maybe three times. it keeps you busy.

Ben

 

[JoeyGST]

I also made the leak tester as shown on the VFAQ. It didn't
work very well at all. Someone should just write up a new
VFAQ. Bicycle pump got me no where.

I ended up borrowing my friend's Leak tester that he bought from
MachV. It has a quick connect for compressors. I brought my car
over to my friend's and used his air compressor to test.

I found a HUGE leak at the Jpipe. I couldn't sustain more than 2psi
of pressure. Apparently, the leak at the Jpipe is a common problem,
so check there. I simply stuck my hand around the flange and I
could feel air rushing out. I found out that the metal gasket was
cracked and the Jpipe itself was leaking by the welds on the flange.
Replacing the metal gasket and a new Jpipe fixed the leak there.

I tried pressurizing the system again, this time it goes up to around
5psi and then no more. I found yet another big leak by the BOV.
I tightened down the BOV as much as I could and that stopped the
leak there at the flange. I want to try and test it again, but now the
air is going out of the lower nipple on the Greddy BOV. The manual
said to leave that nipple open, so I don't know if I should block it
off to test.

-JoeyGST

 

[DSMJim]

Your compressor shoudl be strong enough to bring it upto 25psi or higher no problem even with leaks. I shot mine upto 30psi just to make sure everything was ok..

Just went out with 21psi on pump 50trim and she hauled alot more arse than normal. Just going to check my log now and see what happened to my timing and O2 voltage...