mrohitredd

So i got the Timing Belt & Water Pump about a week ago... This was quite a job, so got it done at Monro... When i took the car out, i was told that there is an exhaust leak which we might have to fix soon... Spot on... 2 days later - i see the CEL. Got the codes - P0420. Looked around for what reasons it could be the cause & Exhaust leak is one of the reasons... How can i check this ? How can i detect where exactly the leak is ?

The car sounds different, post water pump & timing belt change... Was told its all due to the Exhaust Leak...

ezone

Fix leak, see if code stays away?
Use up to 4 of your 5 senses: Smell, sound, touch. And sight.
(I don't think taste can help on this, but you can try it if you want. LMK if you do any good with it.)
I'd rely heavily on my ears first to figure out where the noise comes from.





Is this not the sort of answer anyone expects from me?
Need different ideas?
Bad cat is on the list too.

mrohitredd

https://drive.google.com/file/d/0B1x...ew?usp=sharing


https://drive.google.com/file/d/0B1x...ew?usp=sharing


These are two small video clips.. i recorded while on idle & with gas... I dont see any visible leaks (smoke)... what & how else can i check ?

ezone

I freekin hate that video player google uses. Doesn't work on my FF and takes forever to run on IE.


You wouldn't see smoke unless the engine smokes.
You should be able to smell raw exhaust if it's leaking between the engine and cat.


I hear the snapping got loud upon initial acceleration (throttle blip) and I can hear the individual snaps of a single cylinder firing instead of all 4, so that means to me the leak should be up top in the manifold area.
It's probably louder and more apparent when you first fire up the engine from cold start, and diminishes as the exhaust manifold gets heated up.
I'll guess you probably have a cracked manifold casting, probably near the middle. They do that.
Could be leaking between manifold/gasket and head or have broken a stud or two from the head, but cracks are more common.

Use a rubber hose held to your ear as a stethoscope. Short chunk of garden hose or something would work.
Poke around with the other end until you figure out where it's loudest. Blip the throttle repeatedly if you have to to make the snap more obvious. (Blip does not mean to rev the engine up.)
If you actually get close to the leak with the end of the hose, you may feel it in your ear as well as hear it loud.

Have a helper get a soaking wet towel and stuff it up in the tailpipe while the engine is running and you are listening for the leak, this will create backpressure in the exhaust system and make leak more obvious. Helper probably won't want to do this very long though.


You could look up in the area around the top O2 sensor and maybe see a crack if there is one.
There is usually black soot immediately around an exhaust leak.

Remove heat shields to see more area. Use mirror and light if you don't want to pull shields off, but it may or may not help.


Manifold and cat are a single unit on DX and LX, and a high quality replacement is not cheap.
Brazing has been mentioned as an option for filling cracks.