exhaust leak??? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

89s132b · 01-12-2004, 11:10 AM

I have an SR20det with stock t25 and stock manifold. When I turn off my car, I hear a hissing noise, like air escaping for about 5 seconds. I cannot pinpint it, but it definately sounds like it is comming from somewhere around the turbo. I cannot hear the hissing while the car is running.
The car runs and boost great except it slowly falls off from 1 bar to 0.6-0.7 bar at 5k-7k rpms.
Does this sound like an exhaust leak?
If it is, could it be responsible for the boost fall off?

uiuc240 · 01-12-2004, 01:30 PM

type "Intake Pressure Tester" in google and build what you find. You have a boost leak somewhere...I'm 99.9% sure of it.

Or, just try tightening clamps for all the IC piping. Exhaust leaks are loud and farty, and they don't appear after you turn the car off.

However, the hissing sound AFTER the car is off is a little strange to me. The pressure tester is cheap though...try that first.

Eric

89s132b · 01-12-2004, 01:36 PM

GREAT!
thanks, I have a friend who has built one already so I will just borrow his. I hope it is a boost leak cause fixing it should lead to some performance gain.

is300drifter · 01-12-2004, 03:09 PM

press you brake pedal after the hissing noise has stopped, is it hard to press on the first try??....to me it sounds like a vaccum leak since there is no boost pressure in the system when you turn your car off from idle (that is unless you rev the thing and turn it off...still no boost though).

....but with the pressure tester you will find the leak.

89s132b · 01-14-2004, 04:06 PM

I tried the brake pedal test and yes, it is hard to press the first time after turning off. I checked it against my accord and my accord still has decent pedal feel for 3-4 pushes. So yeah, I am thinking vacuum leak.

But isn't a vacuum leak the same as a boost leak? I mean my car constantly goes from vac to boost so isn't it the same.

In other words, will my car be faster when I fix this? I wasn't too impressed with my 13.9 on 0.8 bar at the track.

Steeles · 01-14-2004, 04:16 PM

yep you got a leak.

I'm tacking mine down this weekend. I think mines the BOV though....

uiuc240 · 01-14-2004, 10:29 PM

Quote:

Originally posted by 89s132b
But isn't a vacuum leak the same as a boost leak?

yes, unless there is a check valve installed on the particular vacuum/boost line.

as for your track time...that's really not that bad.

Eric

01-12-2004, 11:10 AM	#1
89s132b Zilvia Member Join Date: Apr 2003 Location: Oklahoma Posts: 220 Trader Rating: (0) Feedback Score: 0 reviews	exhaust leak??? I have an SR20det with stock t25 and stock manifold. When I turn off my car, I hear a hissing noise, like air escaping for about 5 seconds. I cannot pinpint it, but it definately sounds like it is comming from somewhere around the turbo. I cannot hear the hissing while the car is running. The car runs and boost great except it slowly falls off from 1 bar to 0.6-0.7 bar at 5k-7k rpms. Does this sound like an exhaust leak? If it is, could it be responsible for the boost fall off?

01-12-2004, 01:30 PM	#2
uiuc240 Nissanaholic! Join Date: Apr 2002 Location: Naperville, IL Age: 46 Posts: 2,093 Trader Rating: (0) Feedback Score: 0 reviews	type "Intake Pressure Tester" in google and build what you find. You have a boost leak somewhere...I'm 99.9% sure of it. Or, just try tightening clamps for all the IC piping. Exhaust leaks are loud and farty, and they don't appear after you turn the car off. However, the hissing sound AFTER the car is off is a little strange to me. The pressure tester is cheap though...try that first. Eric __________________ 2002 Mazda Protege5 1989 S13 w/SR20DET (sold)

01-12-2004, 03:09 PM	#4
is300drifter Join Date: Aug 2003 Location: raleigh, NC..va beach, VA Posts: 33 Trader Rating: (0) Feedback Score: 0 reviews	press you brake pedal after the hissing noise has stopped, is it hard to press on the first try??....to me it sounds like a vaccum leak since there is no boost pressure in the system when you turn your car off from idle (that is unless you rev the thing and turn it off...still no boost though). ....but with the pressure tester you will find the leak. __________________ is300 wagoslide S13 sr20det drift whore

01-14-2004, 04:16 PM	#6
Steeles Post Whore! Join Date: Sep 2002 Location: 7th layer of hell, special pit of anger Age: 48 Posts: 3,785 Trader Rating: (0) Feedback Score: 0 reviews	yep you got a leak. I'm tacking mine down this weekend. I think mines the BOV though.... __________________ Keeping it Godzira bishes. So I murdered another turbo

01-12-2004, 01:36 PM	#3
89s132b Zilvia Member Join Date: Apr 2003 Location: Oklahoma Posts: 220 Trader Rating: (0) Feedback Score: 0 reviews	GREAT! thanks, I have a friend who has built one already so I will just borrow his. I hope it is a boost leak cause fixing it should lead to some performance gain.

01-14-2004, 04:06 PM	#5
89s132b Zilvia Member Join Date: Apr 2003 Location: Oklahoma Posts: 220 Trader Rating: (0) Feedback Score: 0 reviews	I tried the brake pedal test and yes, it is hard to press the first time after turning off. I checked it against my accord and my accord still has decent pedal feel for 3-4 pushes. So yeah, I am thinking vacuum leak. But isn't a vacuum leak the same as a boost leak? I mean my car constantly goes from vac to boost so isn't it the same. In other words, will my car be faster when I fix this? I wasn't too impressed with my 13.9 on 0.8 bar at the track.