Pinpointing an exhaust leak

[exile]

I installed my VRS catback exhaust, meghan racing dp, and new o2 sensor housing a few months ago and ever since I've had a small exhaust leak. I can hear it, no one else can but I know it's there. The sound doesn't bother me so much, but recently the fumes that build up in the cabin are getting unbareable.. light headaches while driving.. so on and so forth. I need to get it fixed, I tried fixing it once but I cannot find the leak.

I've used the soapy water trick but it doesn't work very well at all because I don't have a lift. I was curious if anyone had any other tips or tricks..

At least tell me if these ideas would cause any problems..
1) Could I possibly cover up my muffler while the car is running to amplify the sound from the leak?
2) With the car off, can I possibly find a way to pressurize my exhaust from the muffler back without it leaking from the cylinders? Could I pressurize something too much? Would the cylinders just leak the air out?
3) If 2 doesnt work, can I attach my boost leak tester to my UICP pipe that goes to the throttle body and block off my muffler to pressurize the exhaust?


I ran a search for this, and I am suprised I couldn't find anything. I figured this would be a fairly touched on subject.

 

[grnchevyz]

Well, judging by the upgrade you did, only a few spots could be leaking short of a breached pipe.

1- O2 housing to Downpipe
2- Downpipe to CAT
3- CAT to Catback

I'd make sure those 3 links are nice, tight and their respective gaskets are there and not broken.

I'm sure you'll find a leak in there somewhere. Also, the fumes you are experiencing could be that "new exhaust smell" that will burn off eventually.

Hoep this helps.

EDIT: N/M on the new exhaust smell...just re-read and noticed the "installed a couple months ago" part.

 

[oldman]

Make a new tester to fit your exhaust tip and do a reverse boost leak test.

 

[greengoblin]

Smoke is a good way to find an exhaust leak. You can use a smoke machine but since most people don't have one you can use a intake mainfold cleaner like sea foam.

Just start the car pull off a vacuum line and let it suck some of the cleaner in. This will make your car produce a lot of smoke and you should see it coming out from any leaks in the exhuast . It helps to have 2 people one to apply the cleaner and the other looking for the leak. It's good to have a mirror to look in the tight spots.

Good Luck.

 

[kenamond]

Make a new tester to fit your exhaust tip and do a reverse boost leak test.

Couldn't you just cap the exhaust tips, disable spark/fuel, and turn the car over a couple of revs? If the motor/exhaust is cool, you could hit everything with soapy water and have someone look for bubbles. Basically, it's the same idea, but you don't need a compressor or a full-blown leak tester for the tip(s).

 

[exile]

Make a new tester to fit your exhaust tip and do a reverse boost leak test.

You all offered very good suggestions and I appreciate it, fortunately oldman is pretty much telling me exactly what I want to hear since I just bought a $300 air compressor and I want to play with it.

I'm assuming since oldman said so, then the air from my reverse boost leak test will not, or barely leak from the engine (head/pistons..so on.)

 

[oldman]

Couldn't you just cap the exhaust tips, disable spark/fuel, and turn the car over a couple of revs? If the motor/exhaust is cool, you could hit everything with soapy water and have someone look for bubbles.

That will probably work but why not just do what the DMV does, one person listen while the other block off the exhaust with cardboard/cloth while the car idles.

 

[kenamond]

You all offered very good suggestions and I appreciate it, fortunately oldman is pretty much telling me exactly what I want to hear since I just bought a $300 air compressor and I want to play with it.

I'm assuming since oldman said so, then the air from my reverse boost leak test will not, or barely leak from the engine (head/pistons..so on.)

If you do it on a cold motor (maybe a wise idea), the blowby will be higher, and you'll leak boost...err...exhaust leak test air, but you could have someone hit it with 20psi with the oil cap off, stop, listen for leaks/look for bubbles, repeat.

One potential problem with doing this on a cool motor/exhaust might be that the leak seals up when cool. Dunno. I'm curious to see if this works, because I *saw* an exhaust leak when I did my first (and only) seafoam treatment (scared the shit outta me!). If this works out, I'll probably do something similar.

 

[oldman]

You all offered very good suggestions and I appreciate it, fortunately oldman is pretty much telling me exactly what I want to hear since I just bought a $300 air compressor and I want to play with it.

I'm assuming since oldman said so, then the air from my reverse boost leak test will not, or barely leak from the engine (head/pistons..so on.)

You will get the same amount of blow by as if you were doing a leak test. I also suspect that some air will get past the turbo hotside into crankcase just as it would cold side, this will also be a good way to test the exhaust valve seals.

 

[greengoblin]

Tell us how it goes.

 

[Bmxr152]

the best way is to take some kinda hose and put it to your ear and go along pipe listening for hissing or anykinda loud noise. This worked many times for me!