divil

I was pressure testing my intake today and I couldn't get it to hold pressure. I could hear a big leak and it turned out to be from the electrical connector on the cycling valve. This is a brand new CV. I still have the old one so I tested that and sure enough, it leaks out of there too. I did a few searches and it seems to be pretty common, but I can't find any definitive info on where it's a real problem or not. Does anyone know if this is a problem? I am currently chasing a problem with my boost (boost comes on very late). I tried clamping off the pressure line from the banjo bolt to the CV, but that didn't make any difference to the boost. Still, I didn't try clamping the return line, although that seems less likely to be a problem since it's not under boost.

darek_u

My CV was also leaking from the connector (spades) but very slightly under 15psi pressure. I covered area around them with clear epoxy and it is tight now, not the best and most elegant way of sealing of leaks but it works fine for me.

divil

Mine's worse than that I think. My 1.5 gallon compressor can only hold the intake at 5psi for matter of seconds before it's empty. The CV valve is the only thing I can find that's leaking.

darek_u

do you have AOS blocked off when checking?

divil

Yes that's with the AOS hose clamped off at the J-boot.

Tomorrow I'm going to test the boost section only, from the intercooler pipe. Then I can check it from after the banjo bolt and I should be able to tell if the CV is the main leak or not.

darek_u

It is rather unusual that CV is a source of massive air leak unless it is cracked?

divil

It's definitely not cracked. The air is definitely leaking from the connector. The old one I took off is the same. But maybe the noise was masking a bigger leak...I'll find out for sure once I eliminate the CV from the test.

Thom

They do that from new. Never been a problem in my experience.

mel_t_vin

What's the maximum boost you see in 2nd and 3rd? Have you tried clamping the line from the CV to the WG? Caveat: be careful with your right foot when you do this.

I suspect you have a faulty WG or turbocharger.

divil

I see full boost from 2nd upwards. Just takes a long time (3500-4000 rpm in 2nd)

Yes I've tried clamping that line, it doesn't make the boost come on any sooner.

divil

OK so I tested it from the intercooler inlet pipe today. It was leaking fast and clamping off the CV line didn't help much, so I am not going to worry about that leak for now.

I found a big leak at the blow off valve - the screw on the hose clamp was tight but it was not actually clamping. Once I fixed that, it held better - but it still leaks pretty quickly, and silently. If I get it up to 10psi, it'll start losing around 1psi in maybe 10 seconds or less. At around 3-4 it slows down a lot, but ultimately it only holds at about 2. This is with the banjo fitting - cycling valve line clamped off. I've tried listening with a hose, spraying soapy water on every connection I know of...nothing. No sounds, no bubbles, but the air is going somewhere. Any ideas on how to find where it's leaking?

I went for a drive and bizarrely fixing that big leak at the BOV hasn't improved things at all. I know I have a small exhaust leak though, so maybe that's the main cause of my spool up issue.

mel_t_vin

If clamping the hose to the WG doesn't change your boost profile, and you're still getting 15 psi [gauge] of manifold pressure, then you don't have a WG issue.


Well, therein lies your problem.

Define small? And where/how many leaks do you have? I suspect you've got a bigger leak than you think, as your turbo couldn't muster more than 15 psi with the WG line clamped.

divil

I can only find one leak, but you're right, I don't really know what counts as small. I haven't let the turbo boost past stock boost (11psi) when I have the WG clamped...my guess is it would do it in 3rd or 4th gear no problem, although it's hard to read the stock gauge accurately.

The exhaust leak feels fairly weak, but that's at idle of course. It's coming from behind the flange on the crossover pipe where the WG inlet connects. I can't tell if it's the connection or a hole in the pipe, but I'm going to get a new gasket and see if that seals it up.

mel_t_vin

Okay, so with the WG line clamped, you're limiting boost via your right foot. Fair enough.

If you have a leak at the WG flange, that will most certainly divert/bypass exhaust gas around the turbine, promoting turbulent flow to the inducer and affecting spool. To what degree, I couldn't comment.

Regardless, get that leak fixed.

TurboTommy

The amount of leakage you're describing, here, is nothing. The little bit of air that's going "somewhere" is just a bit of it going past the rings on a non-running engine; you can't see it and might not hear it. It's totally normal.
You thinking it's spooling slow is a different story.
Boost threshold/spool test: 4th gear, floor it at 2,500 RPM, and note at what RPM you achieve your full boost.
2nd gear, 3,500, isn't even that bad.