Exhaust Leak is hard to find

Hiboost · Sep 8, 2009, 12:39 PM

So this weekend I ended up being designated driver for a night out and after 4 people piled into the car I tried to back out of her driveway. Turns out the driveway was "settling a bit" on the outside edges but was normal height in the center. My exhaust was scraping slightly with the extra weight in the car for what looked like a 5" difference between the middle and the edges of the driveway.

So now I'm smelling a little bit of exhaust fumes entering the cabin when the vents are set to take outside air in, using recirc seems to make it odor free. Checking the exhaust itself there are no leaks or noises the entire length so I'm pretty sure I have a tiny leak somewhere underhood. I can even smell some of my heat wrap material "burning up" but can't spot where the mystery leak is.

Likely places are the Ultimate Racing O2 Downpipe or maybe the ETS tubular manifold but you would think most of the stress would have been taken by the UR 02 DP's flex section. I honestly don't hear noises or see any exhaust pulses in that area but I guess it could be a tiny hole causing all the smell.

Any sure fire methods to figuring out where the leak is? Pink smoke into the intake? I'll have to do a more thorough inspection with the car up in the air and use mirrors and flash lights to inspect hard to reach areas.

shyong · Sep 8, 2009, 12:44 PM

Don't know what to tell ya, man. I have the odor anyways with no exhaust leak I can think of. It's always been this way when you have the vent open to the outside. I have had two exhaust leaks in the past and you'll know if your exhaust is leaking. It's very audible.

To tell you honestly, I think the exhaust gases from the exit (tips) somehow back drafts to the front of the car when the ac vents are open. I only smell it if I'm sitting standstill for a good while.

Oh, forgot to mention...make sure the o2 housing isn't damaged. Maybe one of the welds cracked...this attributed to a very strong smell in past.

meckert · Sep 8, 2009, 12:46 PM

have a friend cover the exhaust with a rag while the car is running and you slide under and listen/look for leaks. check all joints with your hand--no dont touch anything, move your hand around the joint to see if you can feel puffs of exhaust.

tsitalon1 · Sep 8, 2009, 12:50 PM

Quote:

Originally Posted by meckert

have a friend cover the exhaust with a rag while the car is running and you slide under and listen/look for leaks. check all joints with your hand--no dont touch anything, move your hand around the joint to see if you can feel puffs of exhaust.

Gonna need long arms to plug both tips

inco9nito99 · Sep 8, 2009, 12:52 PM

Run Seafoam through the car...you'll find it FAST.

.

tonyboy · Sep 8, 2009, 01:02 PM

what i did with my turbo civic before...we had a hard time finding the exhaust leak...but i do smell it...what we did was used an old school type of approach...use of a hose or pipe and point to your ear and point the other end to the gaskets, welds, etc...you will find it

ETS Michael · Sep 8, 2009, 01:51 PM

Sorry to hear about this! It's going to be hard to tell if it hurt the manifold with the wrap on it. Does the downpipe have a flex section?

smoothevo · Sep 8, 2009, 02:35 PM

Don't you have a test pipe? That's probably what you are smelling.

Hiboost · Sep 8, 2009, 03:46 PM

Thanks for all the good ideas guys, I'll see what I can find tomorrow night in the air.

Quote:

Originally Posted by ETS Michael

Sorry to hear about this! It's going to be hard to tell if it hurt the manifold with the wrap on it. Does the downpipe have a flex section?

Yeah I think the wrap is unsulating the noise of any small crack that may have developed and it is also containing the exhaust pulses at idle. Once you get into boost the extra backpressure is definitely venting exhaust gasses from somewhere. The UR O2 DP has a nice flex section in it and after fixing a clunking noise in a hanger in the catback section it seemed to have a good amount of flexibility to it.

Since I smell some exhaust wrap burning up a bit I'll have to likely look for evidence of it seeing high temps or black soot in that area. I'm also going to do some spool tests on the datalogger and see if there are any losses. If the Headers took a hit then any sizeable leak could knock 100-200 rpms off spoolup. if the Ultimate Racing O2 DP is leaking then it should be "faster" if anything. Leaking anywhere else would seem hard to believe but you never know. I checked all the nuts to the Headers, Turbo to DP area and everything looked snug.

As a work around I'm keeping the vents on recirc for now, although placing some foam padding under the back edge of the hood in front of the vents seems to have reduced 90% of the exhaust smell even on outside air, still I know it's there though and it bothers me.

Hiboost · Sep 8, 2009, 03:50 PM

Quote:

I have the odor anyways with no exhaust leak I can think of.

Quote:

Don't you have a test pipe? That's probably what you are smelling.

I always could smell it a little bit but now it's just crazy strong in the car with the fresh air vents on. When you pop the hood it smells like exhaust fumes and burning wrap. Something broke loose, just a matter of finding it.

Quote:

Originally Posted by tonyboy

what i did with my turbo civic before...we had a hard time finding the exhaust leak...but i do smell it...what we did was used an old school type of approach...use of a hose or pipe and point to your ear and point the other end to the gaskets, welds, etc...you will find it

The pipe held up to a suspected leak area should amplify it over the noise of the lifters and such, good idea!

Quote:

Originally Posted by inco9nito99

Run Seafoam through the car...you'll find it FAST.

.

I need to do an oil change soon anyways, so the sea foam / intake cleaner where plumes of smoke will exit the exhaust should find it pretty quickly if I can't figure it out.

robh · Sep 8, 2009, 04:13 PM

do you know anyone with a smoke machine i promiss it will find the leak

Hiboost · Sep 13, 2009, 04:09 PM

Was at the Street Car Shootout this afternoon sponsored by STM and best I could pull was 12.1 @ 118 because I could not get the car to launch to save my life. To run consistant 11.70's I need 1.7x short times and I just could not get better than 1.95 due to bogged launches or mad wheelspin with some wheel hop. The other two runs where I bogged off the line the car was making like 10 psi of boost up until 4000 rpm which is just horrible. Once you are above 4k in 2nd-5th then the lag isn't so bad but the slight leak is really hurting responsiveness with 20 psi at 5500 rpm's in 1st.

I did some 4th gear spoolup tests and 20 psi won't hit until 3800-3900 where as before I easily had that at 3600. The Pro tree is a pita in that I can only build 6-8 psi where as before I could get 10 psi no problem so I've got to get this fixed if I want to drag race competitively. Time to pour some smoke through this thing to locate the leak!

laksman91 · Oct 26, 2009, 07:53 AM

I've got a testpipe and that is contributing to a foul smell inside the car. What solutions would I have? (slightly related to this)

goofygrin · Oct 26, 2009, 08:46 AM

Check the o2 housing. The difference in the amount of "give" between the AMS o2 housing and the UR one is amazing.

laksman91 · Oct 26, 2009, 10:07 AM

what would i be looking for in the o2 housing?