boost leak help

[97gsx_zeclipse]

got a question about a boost leak test and its driving me crazy trying to find this leak. my bov is recirculated and used to be loud but now its a very quiet flutter. plus when my car boosts it used to put me in my seat and pulled hard, even on the stock t25. but now just sounds like a powerful 4 banger. and you can barely hear the turbo spool anymore. car seems to idle fine and run fine, no cel. so im stumped really. Ok car warmed up, placed the tester on the turbo pressurized it and it only goes to 3 psi. Air coming out of the dipstick and took off the oil cap, I can hear a loud hissing, also hear air coming out of the exhuast. So I turn the crank 30 degrees and no longer hear air coming out the exhaust, (i think). but still air coming out the dipstick and oilcap. oh and my car doesn't smoke when driving or idleing. really getting on my nerves that i cant fix this and i really dont want to drive 100 miles to road race engineering for them to do a complete boost leak test for 80 bucks and then i have to drive back home. any ideas? oh and i replaced my pcv about 3 weeks ago, i got it from autozone. thanks

 

[Boostin2High]

What kind of BOV is it?...The samething happend to my forge..the spring in it snapped in half..also too. another problem i came across that caused the same problem as your was the cotter pin on my wastegate actuator broke so it caused no boost and no BOV...check them both...

 

[97gsx_zeclipse]

Type RS bov, its new. I read a lot that it might be the pcv valve. I did get it from autozone. I just got a new one from the dealership. Hopefully that works. Going to do another boost leak test tomorrow. But can it really leak that bad just from the pcv valve?

 

[EVOL_TURBO]

unscrew your PCV, hook it back up to the hose, hold it at the same angle as if is was still srewed in and then do your boost leak test. See if it leaks!

 

[97gsx_zeclipse]

Ok I'll do that and get back to you tomorrow. Got to go to work. Thanks

 

[97gsx_zeclipse]

I got the OEM pcv and replaced it. Still didn't help with the boost leak test. Car was warmed up and hooked up the tester to the turbo. Still only goes to 3 psi. Still leaking out the dipstick and hear a hissing when I take out the oil cap. Car doesn't smoke either. Barely hear the bov. Anyone have any ideas to what it could be?

 

[SFRacingGST]

when you do a boost leak you wannt start as close to the TB and work your way back. When you put it on the turbo, the pressure builds also into the oil system (you might hear a gurgle from the oil pan). Start on the TB elbo, then go to the other side of the IC and further from there. Make sure the system will hold a good amount of pressure for about 10-15 sec.

 

[kmoore]

Is there any air rushing out of the opening of your Greddy Type RS when you pressurize the system?

 

[95CarbonEclipse]

unscrew your PCV, hook it back up to the hose, hold it at the same angle as if is was still srewed in and then do your boost leak test. See if it leaks!

Do this!^^^ While it's unscrewed and you're doing your boost leak test, put your thumb over the PCV snorkel and check to see if that's where your leak is coming from. It's not uncommon for even an OEM PCV valve to leak right out of the box.

I suggest puting a check valve inline between the IM and the PCV to prevent this in the future ....and save yourself from changing PCV valves every 2,000 miles.

 

[97gsx_zeclipse]

Is there any air rushing out of the opening of your Greddy Type RS when you pressurize the system?

The first time I did a test it was a lot rushing out. I had to turn the adjustment screw almost all the way hard to hold. It pulls a little better now but still not like it should, plus the bov its a really quite chu chu flutter. It used to be a loud agressive sound, even with the recirc tube on.

 

[97gsx_zeclipse]

Do this!^^^ While it's unscrewed and you're doing your boost leak test, put your thumb over the PCV snorkel and check to see if that's where your leak is coming from. It's not uncommon for even an OEM PCV valve to leak right out of the box.

I suggest puting a check valve inline between the IM and the PCV to prevent this in the future ....and save yourself from changing PCV valves every 2,000 miles.

So the OEM pcv can leak out the box from the dealership? So I take out the pcv and plug it and do the test? Wont the small opening from the valve cover leak?

 

[kmoore]

Your diaphram on your greddy type rs is stuck open.

 

[Jordanbutter]

I have the same problem with my greddy rs execpt its only letting out a bit of air but it never used to do that, so I'll ask the question for him, is there anyway to fix that?

 

[95CarbonEclipse]

So the OEM pcv can leak out the box from the dealership?

Yes, even OEM dealership PCV valves aren't that good. Even if it is good out of the box, they typically don't last even 3,000 miles. Search for the thread "Stupid PCV question" and read up on that, it's kinda lengthy, but very informative.

So I take out the pcv and plug it and do the test?

Yes, remove the PCV valve from the VC but keep it connected to the hose that goes to the IM. Then, while pressurizing put your thumb over the PCV snorkel and see if it's leaking. If it is... your PCV is bad and you should put a check valve between the IM and the PCV valve.

Wont the small opening from the valve cover leak?

No, your VC shouldn't because the VC shouldn't be pressurized at all. The only way for air to get into the VC, would be through the PCV valve.

 

[95CarbonEclipse]

What kind of BOV is it?...The samething happend to my forge..the spring in it snapped in half..also too. another problem i came across that caused the same problem as your was the cotter pin on my wastegate actuator broke so it caused no boost and no BOV...check them both...

Please read his entire original post. Based on what he's said it's not the BOV that is the problem. The BOV sound is a result of a boost leak. The reason it's fluttering is because there's a leak somewhere that isn't allowing him to build enough pressure to allow the BOV to open like it should.

 

[Boostin2High]

Whatever you say buddy...

 

[97gsx_zeclipse]

Oh I didn't know that the VC can be pressurized only through the PCV. That makes more sense. Ok I'll do the test again and see if it helps. You would think buying the parts from the dealership would be legit but this would be the third piece of junk I bought from them, if the pcv doesn't work, cost me 13 bucks for the stupid pcv.

 

[kenamond]

The BOV has nothing to do with the boost leak showing up under the VC. The flutter you described sounds like it might be surge, but words suck at describing sounds. You should be able to test the BOV with a vaccuum tester, though (follow the instructions in the Haynes/Chilton manual for the turbo bypass valve).

The VC can leak from other than the PCV. Intake valve stem seals connect the intake runner to the top of the head; you pressurize the intake (and runners), and it leaks past the valve guide seals into the VC.

Also, if you have poor compression, the boost test air will blowby the rings, return up the oil return passages, and come out the head.

Pull the PCV from the VC, remove the oil cap, and repeat the test. If air is coming out the PCV, the PCV is bad, and you should replace it or go get a check valve (read the "Stupid PCV Question" thread). If it's not leaking, cover the snorkel on the end of the PCV valve. If it's still hissing in the VC, make sure you're not in a valve overlap crank position (rotate the crank more than 20*) and repeat. If it continues to leak into the VC, I'd recommend a compression test and leakdown if you find a compression issue.

 

[97gsx_zeclipse]

Thanks man. You explained good to where I get it. I thought the leak down test is the same as a boost leak test. I looked in the repair manual and it talks about leak down test, but I can't find it anywhere in the manual. Do you know the page?

 

[kenamond]

Thanks man. You explained good to where I get it. I thought the leak down test is the same as a boost leak test. I looked in the repair manual and it talks about leak down test, but I can't find it anywhere in the manual. Do you know the page?

The leakdown test helps identify what is leaking in the combustion chamber (valves, valve seals, rings, gasket). The boost leak test identifies leaks between the compressor outlet and the combustion chamber (all the intake that sees turbo boost pressure). Boost leaks are a problem, because the ECU gets its air measurement from the MAS which is pre-turbo, so if you leak any of that air, the ECU doesn't know about it and thinks the engine is getting more air than it actually is, and it injects too much fuel. That makes you run rich which robs power and fuel economy, and if bad enough will make the car run like crap.

So if you don't have a bad PCV valve but you're still leaking out the oil cap during a boost leak test, you have to find out if it's ring blowby, head gasket, or valves. If nothing shows up, it's probably intake valve guide seals.

Anyway, you start with a boost leak test (looks like you were doing it right) and start zeroing in on what's leaking.

The turbo bypass valve test procedure in my manual should appy to any BOV. You put a vaccuum tester on the nipple (where the hose goes to the IM) and apply vaccuum. The valve should start to open at 16 in-Hg for a stock 2g BOV. If it's not opening at around that vaccuum, it may lead to compressor surge which is very hard on your turbo.