Archangels

long story short, i was at the track boosting in 4th gear on a straight when all the sudden i heard a pop noise, more like a bunch of air gushing out from somewhere, immediately i got off the gas, pulled over where it was safe and when i checked over the car everything seemed fine other then the turbo's hotside glowing red, i got it into the parking lot, checked it over, drove fine, seemed to boost fine, but the turbo seems to have a little more lag to it and overall the car seems a little, slower?...

either way, when i boost 13psi give or take i hear a weird "flapping" noise, the turbo seems alright but the boost is off, it spikes a little higher now and surges once in a bit....

any idea off the top of you're head as to what may be wrong?, i'm putting a boost-leak tester on the car tommorow morning to pressurise the system and was wondering, is there anything i should know and/or be careful of?, i know above 15psi of boost nasty things can result like chucking seals and what-not but is that the same when the engine does not see load?, what psi should i pressurise the system at to check for leaks?...

arghx

iTrader: (3)

I presume you are installing the pressure tester to the inlet of turbo. Just as an aside, you can install a pressure tester in a bunch of different locations. I've installed them directly to intercooler pipes (this was on a turbo civic). With the engine out of the car I installed a tester on the TB elbow so I could fix any vacuum leaks before the motor went in. I have seen various rigs to test for exhaust leaks (most involve plugging the tailpipe). I have seen custom LIM pressure testers as well (FD shown):


First, turn the regulator on the air compressor all the way closed. Hook up the pressure tester and then connect the air hose. Slowly open the regulator and you'll hear air flowing through the system. Listen for hissing sounds--there should be a sound of air flowing through the plumbing, but not the hiss of an air leak. Feel around blockoff plates (upper left corner of ACV plate especially), piping couplers, TB elbow o-ring. Put your hand up to the BOV outlet and make sure it's not leaking; if it is, it needs to be adjusted or repaired. Feel under the UIM, you may have air escaping from around the secondary fuel rail or any other kind of plumbing under there. Check around the IAT sensor in the TB elbow, that likes to leak. Any kind of threaded fitting that's exposed to charge air is prone to leaking, especially if you used teflon tape. I hate that stuff and I prefer some form of RTV on the threads, usually gray or blue (black is thick and hard to work with).

I also had some kind of weird leak from the thermowax area of the TB. It almost looked like it was supposed to be there... I just put some RTV in the area and it sealed up. One other guy I remember posting about the same issue said that sealing up a similar leak affected his idle quality. I don't know what else to say about that.

To directly pinpoint leaks, get an empty spray bottle of Windex or something similar. Fill it up with water and a pretty small amount of soap. Spray the soapy water in areas that you suspect have air escaping. Finding leaks under the UIM is tricky, and that's why some have made those custom testers like the one above.

Also, don't pay much attention to the pressure gauge on the regulator--it doesn't matter how much pressure is coming out really. It matters how much air the boost gauge in the car reads, or the gauge on the tester. At about 15psi on the car's boost gauge you will begin to reach the limits of the worm clamps on the tester. At that point, you may hear a violent popping sound and the tester will fly out due to insufficient clamping force. Don't be alarmed by this. Heck, it's kind of a good thing in a way. Sometimes the boost leaks are so big that you can't even get pressure to hold high enough to blow the tester out.

Finally, keep in mind that this isn't the kind of pressure test where you fill the system up with air and see if it will actually hold pressure for a given period of time. The charge piping and associated plumbing is not a sealed system. Air is going to escape out the exhaust ports, but that's ok. You are testing to locate where air may be escaping out (vacuum leak or boost leak). You are not testing to hold pressure.

Hope that helps.