Boost leak at 10psi

Hey all,

Haven't been on in a while, last weekend whilst towing my motorbike out to cooyar I heard this strange hissing sound coming from under the bonnet, checked all the obvious boost/vacuum lines, intercooler piping and boost gauge line, no avail. It only happens around 10psi and above and has a mad almost tyre deflating hiss under load, only over 10 psi, anything under is quiet. I figured it could possibly be the egr but I'm unsure..... The intercooler piping is looking pretty crap as it is (done nearly 400,000 between 3 engines) so I'm gonna replace it along with some vacuum lines.

So my questions are:
1. Where could the leak be coming from?
2. Does anyone know if anyone sells a intercooler silicone hose kit?
3. Where are ALL the vacuum lines? (I've found turbo, ebc, one that hides up the back of the intercooler) AND
4. Will the aftermarket cruise control have a boost line? (A little random but there's a boost line that goes over to the drivers side to a module which I have nfi what it is)

Cheers all

Vacuum solenoid is next to air cleaner box, that line that goes to drivers side is to Vacuum pump from memory.
Is the exhaust in good nick behind the Turbo, mine cracked there but more a "pit too" sound.
I've only changed one hose to silicon, expensive bloody stuff, You may want to blank off EGR if not done already.
Yours has probably got a vacuum canister under the engine cover too. You may want to think about fitting NADS.?

Yeah I'm fitting nads slowly, the Dawes valve and needle are going to be the hardest I think. Out of curiosity what size is the pcv pipe? 3/8"?

PCV pipe ??? not with you one that one

Quote:

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Originally Posted by threedogs

PCV pipe ??? not with you one that one

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What size hose to fit the PCV filter?

Yeah there's a pipe that goes from the pcv valve to the air inlet

Anyway I've redone the intake manifold/throttle body gasket, replaced 2 pipes with silicone replacements and secured all pipes with proper t bolt intercooler clamps, but yet there's still a whistle, starts low pitched at around 6 psi then gradually gets louder til 10 psi where it peaks. I lost for ideas, anyone else got any?

Turbo's do whistle as they spin so fast. Those clamps are great too,
Your boost is low , I take it you haven't fitted the DAWES valve yet.
You're getting there, try to do one thing at a time that way you'll know
what it is. Do you think the EGR pipe could be split and hissing under pressure.
You could easily dismiss this by fitting an EGR blanking plate, one less thing

Was a thread recently where noise increased after engine warmed up
is the noise consistant with REVs

It's weird, it happens with the turbo pressure, not engine revs ( be leaning to exhaust leak), I have an auto so it does weird sh!t. It could be an egr problem but at the exhaust end not the intake end at a guess..... How hard is it to remove both end of the egr system on the non crd ones, cause the crd ones are hella annoying

can you simulate the whistle manually?.
maybe try leaning over the engine and poor/spray " Hot " water over sus connections and listen for bubbles/spattering.

That's just it I can recreate it with the car parked, it's gonna be hard to find shirt of taking it to a dyno and pinpoint it as it spools

I'd fashion up an EGR blanking plate out of a jam tin lid or similar just to make sure its not the egr pipe that's split.
This is only only to find the noise. but you keep saying its boost related.
what condition is intercooler in??

Near brand new, only done 90,000 if that, still perfectly clean inside, bit of dust on the outside and a couple of dents from stones

Hi Country_Gu. I have my money on the egr pipe has warped where it mounts to the manifold. You will need to remove the entire EGR pipe. Get some wet and dry onto a piece of glass and sand the facing flat. Once done, block the EGR and be done with it....

Cheers.

Mark.

Righto guys I shall have a look tomorrow, thanks for the help, I have a crd egr pipe I "procured" from a job at work, except its off a crd zd30, they have completely different egr systems don't they?

Quote:

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Originally Posted by Country_GU

Righto guys I shall have a look tomorrow, thanks for the help, I have a crd egr pipe I "procured" from a job at work, except its off a crd zd30, they have completely different egr systems don't they?

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Yep,

They connect totally in different spots and are different from what I have heard - DI is at the rear, and CRD at the front and is watercooled.

Anyone want a free crd egr pipe then? Got an exhaust manifold too..... Ill block it and see what happens, also is the vacuum tank that sits beside the intercooler needed? Any advantages/disadvantages in having it?

You talking about the vacuum canister? Beer can sized thingo' with the vac line going in and out? If so, you can remove it if you want. Most of them get brittle and break where the hose goes in, or out. If you are keeping the engine cover on you still need the bracket that the canister mounts in though.

Cheers.

Mark.

Yeah that's it, so no disadvantage without it? Plus with the t bolt clamps I can't put the cover on anymore :/ probably cool the intercooler a little better without a piece of plastic blocking it

Yeah I use Constant torque clamps and the cover wont fit. So I dont have it on now. With T-bolt clamps you really should use spring loaded ones too. These will never come loose. Normal t-bolt clamps are really designed for boost pressures, albeit not much they are really made for intake hoses...

Spring loaded t-bolt clamp.
Attachment 33076

Constant torque clamp.
Attachment 33077

Mine aren't that flash lol

Photo of about half way through

Attachment 33078

Why not remove your Intercooler and pressure test to see if it has a leak,? easy enough to do

Do I need a special tool or some rags and an air gun?

Rags ,tape and a bike pump and a big bucket of water, don't need big pressures, so go easy

Haha yeah hence why I asked I didn't want to blow the ass out if it, don't need another 1000 dollar bill at the moment lol

If its leaking it would show up easy enough.
I'm not sure if that would be making a noise though,
but one less thing

@ Country GU could you please put what size hose clamps you have used ,
great info for other members IMo

Quote:

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Originally Posted by Country_GU

That's just it I can recreate it with the car parked, it's gonna be hard to find shirt of taking it to a dyno and pinpoint it as it spools

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thats just it sometimes you think it cant be found simply because you cant hear it over the engine.
but it is always worth a try none the less what have you got to lose, nothing.
if it is a leak under pressure you may find, idling it is now sucking air.
with a little luck you could see/hear water being sucked into the hole instead.

Are you loosing boost at all? Or is it just this noise up to 10psi and the car still has boost past 10psi?

The cars still got power, gets closer to 15 psi now with the throttle body cleaned, where it never used to which I thought was a bit suss. @threedogs, yeah mate ill throw them up probs tomorrow, gotta look at em and see what size I used lol but guess I'm off to find a dyno to find the noise after trying some other techniques.

If you checked your intercooler and it is leaking which is a problem I had to which I had a whistle from it as well!.

In saying that nissan charge about $1400 for a replacement intercooler you can get an up market of eBay with a fan for about $1000

But if your strap for cash check out pwr performance they located on the Gold Coast what they do is they swap your old one and give you a tig welded one and you shouldn't have a problem with it again!. It cost $600 I think from memory as was a few months ago I done mine!. Website below

http://www.pwr.com.au/

It was good as I didn't have another way to get there so I drove there checked with them and quickly took it off and swapped it paid for it and put it back on!. Was stoked with it!..

Hope this helps

How are things going with your noise any up dates ??