View Full Version : Hissing Sid!
...is under my bonnet.
When the turbo spools up there's a loud hissing sound. Car seems to be pulling ok but I'm wondering if one of the intake rubbers has a split as the noise seems to be coming from the passenger side...but not all the time :roll:
Are there any pipes down there that are know for splitting?
wrinx
The little pipe that connects to the dump valve seems a little weak to me. I would check that first. Also, the 90 degree elbow to the intake can split too.
Elbow to the intake was new a couple of years ago and I checked it the other day...will check again though ;)
wrinx
Mmm, just found this picture on FCCUK of a split intake rubber:
http://www.fccuk.org/forum/imagepopup.php?image=http://img.photobucket.com/albums/v18/NigelO/Cars/DSCF2117.jpg
The hissing occurs at higher boost/revs so gets worse with increased pressure, I'm fairly sure this is the cause due to the location of the noise :roll:
...although split intercooler is also mentioned as a possible cause of hissing.
wrinx
Wish you the best of fun taking it apart :D
:lol: See my other thread...
wrinx
Right...took the intake tube off and put some compressed air through the inlet...no hissing noises at all, so I can assume the rubbers are fine, bang goes that theory :roll:
Also tested the vacuum hoses and they appeared to be fine too :?
Will have a go at the intercooler and associated pipework but it's on the wrong side for the noise! :?
Anyone know what the vacuum pipe(?) which runs around the coolant tank is for?
wrinx
arjunior45
04-08-09, 07:36
Anyone know what the vacuum pipe(?) which runs around the coolant tank is for?
wrinx
for the Fuel vapour recirculating system.
Intake vacuum hose starts from the throttle body {No9} and the hose that 'return'/bring fuel vapors to the intake manifold {plenum} is one of the two hoses next to the ATS.
There are connections for these two hoses just at the side and under the coolant expantion tank. Check them too.
When you finish with your car, can I send you mine too to check it for air leaks? I hear the same hissing noise from the same part of the engine and I can not find the leak.
arjunior45
04-08-09, 07:58
Mmm, just found this picture on FCCUK of a split intake rubber:
http://www.fccuk.org/forum/imagepopup.php?image=http://img.photobucket.com/albums/v18/NigelO/Cars/DSCF2117.jpg
The hissing occurs at higher boost/revs so gets worse with increased pressure, I'm fairly sure this is the cause due to the location of the noise :roll:
...although split intercooler is also mentioned as a possible cause of hissing.
wrinx
do you have the link for the thread with this image?
That's great, thanks...hoped there were some joints down there :)
Think it might be the thread:
http://www.fccuk.org/forum/ubbthreads.php?ubb=showflat&Number=721936&Searchpage=1&Main=58779&Words=DSCF2117.jpg&Search=true#Post721936
wrinx
arjunior45
04-08-09, 11:56
wrinx,
do you know when does the ‘piloted idle vapour interception valve’ {on the canister} open? When does let the vapours go to the inlet manifold? At idle?
When boost is build up at the throttle body? Or when vacuum is created?
Juan AR155Q4
04-08-09, 15:46
Right...took the intake tube off and put some compressed air through the inlet...no hissing noises at all, so I can assume the rubbers are fine, bang goes that theory :roll:
A pair of intake valves are opened, so you?d never pressurize the circuit (same to other side because of turbo).
You need to put a smoke stick in it :D
A pair of intake valves are opened, so you?d never pressurize the circuit (same to other side because of turbo).
Yeah, realised that but hoped the higher than usual volume of air would produce some strange noise somewhere...it didn't.
So I guess the verdict really is inconclusive.
Smoke bombs...sounds like fun??? :lol:
wrinx
What pressure can the standard intercooler take before popping its sides?
I'm getting a lot of hissing from the drivers side at around 3,000 revs and 0 bar :roll:
wrinx
A pair of intake valves are opened, so you?d never pressurize the circuit (same to other side because of turbo).
im always test my system this way
i put air but not more then 1.0bar from the intake pipe of the turbo or from the small vacuum pipes on the intake
(disconnect the air filter and put something to stop the air ,a spray bottle of paint is fine)
you have a pair of inlet valves open but the exhaust are closed
you have air leak from the engine but is very small you can keep the press to 1bar easy by putting air again
the most times you can hear the leaks
but i make a spay vaporizer with water and soap (liquid for the dishes )
and you can see the bubbles :smile:
from the passenger side there is the tube that goes to canister
i use to have a leak from there
the tube is very close to the egr valve and makes a hole from the heat
arjunior45
08-09-09, 13:26
from the passenger side there is the tube that goes to canister
i use to have a leak from there
the tube is very close to the egr valve and makes a hole from the heat
that hose gives a coolant leak and usually you do not hear it. You can just see coolant coming out from this tube or coolant level go down quite soon.
arjunior45
08-09-09, 13:31
What pressure can the standard intercooler take before popping its sides?
I'm getting a lot of hissing from the drivers side at around 3,000 revs and 0 bar :roll:
wrinx
usually it's up more than 1,4 bar.
'Driver's UK side' or 'Driver's continent side' {passenger UK side}?
What about your boost levels?
Q4s are all the same, so "drivers side" is the same as yours ;)
Boost levels are set at 1.0-1.1 and it seems to reach that level fine...but with all this hissing!
Idle is a bit lumpy and with the stalling (until it's been running about five minutes), I need to remove this as a problem as it won't be helping.
wrinx
arjunior45
09-09-09, 11:11
apart the small bore hoses, the plenum-inlet manifold hoses, the inlet manifold gasket and the intercooler {with it's hoses : turbo -> intercooler, intercooler -> -> plenum} you could check even the 'one-way' valve on the servo brake mechanism. It's on the driver's side and can give a 'hissing' sound, not that loud though.
This is very loud, I think it's the inlet somewhere...just putting off removing the plenum :(
wrinx
why you dont pressurize the system as i do?
it is a very simple and very accurate method
you can see the bubbles from a mile you can find the big and small leaks very fast
the only thing that you have to do is to remove the hose of the air filter and put something on the hose to stop the air
and put air with pressure from a hose ...like vacuum hoses or the oil vapor hoses that comes to the inlet
please believe me i make it 2 times a year and every time that i make work with the hoses
that hose gives a coolant leak and usually you do not hear it. You can just see coolant coming out from this tube or coolant level go down quite soon.
Nick sorry i mean the canister for the fuel vapor
there is a tude that start from the middle of the plenum
and pass very close from the egr and the oil reservoir goes down from the water expansion tank and goes to the one way valve near to the fuel vapor canister or filter as called sometimes
arjunior45
09-09-09, 14:28
Nick sorry i mean the canister for the fuel vapor
there is a tude that start from the middle of the plenum
and pass very close from the egr and the oil reservoir goes down from the water expansion tank and goes to the one way valve near to the fuel vapor canister or filter as called sometimes
you mean the 'vacuum intake for the fuel vapour recovery system' {see picture attached earlier in this topic http://forum.berlinasportivo.org/attachment.php?attachmentid=1119&d=1249368462 }. Yes, this is one of the 'small bore' hoses that can leak, but it's from the opposite side of the 'driver's side'.
why you dont pressurize the system as i do?
I plan to...thanks for the tip ;)
wrinx
arjunior45
02-11-09, 15:10
...is under my bonnet.
When the turbo spools up there's a loud hissing sound. Car seems to be pulling ok but I'm wondering if one of the intake rubbers has a split as the noise seems to be coming from the passenger side...but not all the time :roll:
Are there any pipes down there that are know for splitting?
wrinx
I finally found the air leak on my Q4, after a couple of days with idle speed at 1700 rpm. It's 'just' the inlet manifold gasket at cylinder No 1 !!!
What a pain! Glad you got it sorted though.
My hissing seems to have gone....glad I didn't have to remove mine in the end.
Hissing Sid was caused by the MBC! I think it must have been stuck so excess air was coming out of a little hole in the body :roll:
Stuck it in the engine bay now...until I fit the GIZZMO :cool:
wrinx
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