Boost leak test result......

[AbsoluteGTR]

Okay well I did a half-assed attempt at doing a boost leak test. I did go out to walmart and bought a 7 gallon air tank. Anyways, when doing this test, I did it by myself, i know its not good because you need someone to watch the boost gauge, but i was by myself. Still I only would pressurize it for maybe 10 seconds MAX. Anyways, i must have a massive boost leak. Pressure would not hold for the life of me after I took off the air source.

Okay, well there was a hissing sound coming from under the oil cap, so I took it off and then there was the sound of a release of pressure...what does this mean?

Also I was holding the breather hose, because otherwise all the pressurized air was escaping, is this what I am supposed to do?

Any help and comments?

Thanks

[kjewer1]

What is the compression on this motor? Most likely you have a bad PCV valve, but it could also be the rings.

Edit> I also just noticed that you already had a boost leak test thread going. Keep all info on the same topic in one thread, you're lucky if you get a reply in once place, there's no way I'm posting the same info in two threads

[AbsoluteGTR]

My compression results where 160, 155, 150 and 170. I was thinking PCV valve as well but was not too sure.

The boost gauge will get to around 6 psi and then descend immediatly, it holds no boost whatsoever. It seems as though all the air is coming out of the breather hose...Is this due to a faulty pcv valve?

[Killa]

my boost leak test with gauge, will come on tuesday, so I really dont know how it work yet, but for me if I saw a leak, I fix it. Like you if you saw a leak comin out from a hose, get a new hose and seal that leak up.

[AbsoluteGTR]

Originally Posted by Killer7

my boost leak test with gauge, will come on tuesday, so I really dont know how it work yet, but for me if I saw a leak, I fix it. Like you if you saw a leak comin out from a hose, get a new hose and seal that leak up.

lol, thanks killer, but i wish it was that easy. The hose isnt attached to anything...it is my breather hose, the one that runs of the left of the valve cover, but air shouldnt be getting there, thats why i think the pce valve is bad.

BTW, kevin, I wouldnt have bad valve seals, just because my compression is right up to par, correct?

[Killa]

Replace the pcv any way, it cheap.

[AbsoluteGTR]

Okay well i just checked the pcv valve, and it seems as that that is the problem as to why there is blow-by. When I first took it out it was clogged, and would let ALL air pass through in both direction, but now it will only allow minimal amounts of air into the crankcase. So i have to get another pcv valve...no biggie.

Anyways I decided to do another boost leak test, and this time placing my thumb over the pcv valve. Air is still escaping but alot slower now. The funny thing is I did not hear any hissing sounds, I guess I will have to try the soapy water thing again.

ALSO, just for future reference, how long should boost hold in a pressurized system when performing the boost leak test? Should it hold indefinitly or just for like 30 seconds?

EDIT> Should I buy a pcv valve from like autozone or is it better if it OEM?

[kjewer1]

I think any PCV valve will do. I had a feeling that was going to be it.

THe rule of thumb I use is to test to 20-30 psi, it will drop relatively quickly to about 10 psi or so, and I like it to take at least 30 seconds to drop from 10 to 0. There will always be some air that gets by the rings on cylinders with intake valves open, because of the gaps at the ring ends. Doing the test with the motor fully warmed up can sometimes help this a bit.

[AbsoluteGTR]

Well i installed the pcv valve today and I am the stupidest motherfucker out there. When screwing it in I tightened that pcv valve down and I ended up breaking the threads and the housing part of the valve cover. The pcv valve will still hold there very strongly, but I dont like the idea of my valve cover being partially broken. How serious is this? No air leaks through the threads....let me post up a pic.

[kjewer1]

IF it doesn't leak, drive it on. There isn't a ton of pressure on those threads anyway, since the valve cover is vented through the other port.

This isn't all that uncommon. The vast majority of people just don't know much about different types of threads and fastening techniques which leads to leaks, breakage, reliability problems, etc. I go through the same thing at work all the time where we deal with pressures that cars will never even come close to. Same principles apply.

[AbsoluteGTR]

Sorry for the poor ass pic, just got my digital camera today (12 megapixels) and still figuring out how to use it.

Anyways, the car seems to be just a little bit faster, but there is still a leak.
The turbo sounds like it is working its ass off, and the rpms rise fairly slow compared to all the noise being made. Hey kevin, my preload is off? Could that be the problem?


I still am having trouble with the damn boost leak tester...dont know what I am doing wrong but ALOT of air will still leak out through the breather and if I hold that hose closed, and open the oil dipstick, it just comes out through there!

I need some help on this, please.

[Thor06]

12 mega pixels dear god!!!

So where is the PCV valve you speak of and could it be the reason for a late spool time?

[AbsoluteGTR]

The PCV valve is already on the car. First drive, the car felt a little faster, but my cavalier would smoke it. Second drive, the car would barely gain speed, and once it dropped down to 500 rpm.

My vacuum is at like 17.5 at idle and around 27-28 in between shifts. Is this normal? My max boost is 9 psi....should be like 10.5, right?

Anyways, right before I arrived home, I stopped and I was like WTF I really want to do an AWD launch, so I attempted to rev it up to 5500 rpm and it wouldnt (was not able too) go past 4K rpm. WTF? So I let of the throttle and gave it some throttle once again, and the rpm's just shot right up there...really wierd.

BTW, when the rpms shot up there, I let go of the clutch perfectly...my head snapped back and there was massive torque steer....unbelieveable. That made my day! Okay no more launches for a while....

Anyways, what the hell is going on? Also after these short drive, there was a good amount of steam coming out of the oil dipstick.....

[kjewer1]

Sounds like you may also have an ignition problem (look at the usual things, new plugs gapped properly, etc), fuel delivery/airmetering perhaps (but less likely than ignition)