Today my friend and I finished boost leak testing my car. I just wanted to share some of the results, from a first-timer.

Here is a diagram of the leaks I had when we started. Excuse my freehand MS Paint drawing



Most of the leaks at the couplers could be fixed by putting the clamps a little closer to the edge of the coupler and/or making them straighter (more parallel to the coupler's edge).

As you can see, I had the same leak in my APS BOV that a few other people had. We fixed it with teflon tape around the threads.

Here is the after-test pic:



As you can see, the only remaining leak is on that one coupler. There are two damn clamps on there, one t-bolt and one worm clamp, and it still leaks. It is not audible at all but if you spray soapy water on it, it will foam up on the top third of the pipe. We messed with it for a while but ended up leaving it since it was so small. We were able to make it better, just not perfect.

The only audible leak in the whole operation was at the BOV screw and the BOV-UICP clamp.

One major lesson learned was USE SOAPY WATER. If not for it, we would have heard only the BOV and been done in 10 minutes, not counting removing the bumper and plastic panels underneath the car. To put that in perspective, with the soapy water we had enough leaks to keep us busy for about 4 hours.

By the way, we built a boost leak tester for $5 . All we took was a valve stem and a rubber PVC hose/cap about 2" long. Drill with a 3/8th inch bit, put the stem in, and put some silicone on it It worked beautifully. In fact, the pressure was our friend, sealing the valve stem even more as it increased. The silicone ended up not even being a factor.

Here is one question: On the street Im running about 20psi. With the MBC at my setting, at 12psi it would start to rattle around a lot. Is it normal for that air bleeding to start that much less than your max boost? I tightened it all the way for the actual testing, so it wasnt a factor then.

I'm anxious to get back to the track and see if my ets & mphs improve any now

 

2-pack of valve-stems - $2.10
2" rubber PVC cap with clamp - $3.10
Drill a 3/8" hole - 3 minutes
Cram the stem in and silicone it - 3 minutes

Having a cheap as hell boost leak tester that works fine - priceless

 

The MBC question is a very good one and one that I'd like to have answered, too. I have noticed the same thing on my tests for my car and other cars where the MBC would bleed off at a lower pressure than where the boost was set. I, too, would crank it down to stop it from leaking, but I wasn't sure if that meant my actual boost was lower than I thought, or if that's just how the MBC works by bleeding BEFORE reaching max boost so that it can open the wastegate in preparation for stopping at the desired boost level.

One interesting note is that now when I do my tests, I can go up to 25psi without any leaks and without the MBC rattling. I run right at 26psi peak daily on alky (3rd gear), so it's not the same offset as it was back when I used to run 21-22psi on pump gas. Strange.

 

Yeah, I assumed the same thing, that it wouldnt be just an on/off signal to start bleeding. Makes sense to me...

 

when i did my test i tested it to 26psi. i had the same leaks in the same spots. i fix the bov with teflon tape. and reajusted all my piping. the one part you have n the piping that is still leaking can be fixed. you just have to keep ajusting it. that one spot took me about an hour to fix. my mbc made that sound as well but i tust turn'd it to make it shut up. lol im now boost leak free.

 

I'll have to do the same on mine either.
Can you tell me what is the inner diameter of the tester? 2" is that correct?

And what about your car? see any changes?

[edit]: I did some more research... and found lets go for 1.5" to 2".

 

Just curious... what did you use to pressurize your setup?

 

We first started pressurizing with a portable battery powered compressor (and battery charger). It would only go to about 12 psi and then top out. I guess the K&N breather and whatever other small leaks were losing all the new air at that point. So, we ended up using a big compressor and it worked just fine. It would go from 0 to 22 psi in about 6 seconds.

I can tell a little difference in how it runs, it feels a lot smoother than it did. Powerwise I cant tell since Ive been easy on the car for the most part. 100's with humidity makes for crappy WOT weather, obviously

 

did u leave the upper pipe attached at the throttle body well doing the test or cap it off i have herd both ways being done...


evoisdream

 

/\ anyone?

 

I've heard both as well but left mine attached. By capping it off, I think having to put it back on would probably open up a leak somewhere else, the way the pipes are made

By the way, this is Buschur's UICP. One thing I thought was interesting about the test was how much the UICP moved under boost. About 15 psi, the pipe really flexed upward. I think this could be part of the reason it was so hard trying to fix the one leak I had left. It's hard to get the two pieces of pipe to meet & stay at a 180 degree angle without any support attached to the car (like the bottom of the stock UICP has).

 

i have a little leak around the intake manafold somewhere i can hear it but cant find it and its not at the coupler at the throttle body............


evoisdream

 

Now before I waste more time attempting this should I have the car warmed up before I attempt this? or cap any of the throttle body hoses off? I was unable to hold any pressure on the system............ I do have a gt3076r so I have a 4" inlet so that made putting the tester together much harder..........