Exhaust leak from new headers

Blair · 10-10-2009, 01:37 PM

Last weekend I installed new JBA shorty headers on my 2010 GT. At cold startup I have a ticking noise that lasts for about 20 seconds then goes away. It is coming from the driver's side of the engine. After the start up, you can't hear noise again until you are accelerating at 50% or more throttle, then the ticking chattering noise comes back.

After a few days I rechecked the torque on the drivers side header bolts and the header to midpipe bolts and everything was tight. Still the ticking continues.

This weekend I loosened all of the header bolts on the driver's side and tightened them again adding another 5 ft-lbs of torque. Now the leak sounds like it has gotten worse. It still stops ticking after the car warms up, but the ticking/chattering noise is a little louder when accelerating.

I reused the stock gaskets per the JBA instructions and they only had 700 miles on them. The stock gaskets are layered composite gaskets and don't look like they would leak even if over or under tightened. I am not sure there is a problem with the gaskets, but should I buy new gaskets and install them and see if that works?

Is the chattering/ticking noise during acceleration just valvetrain noise that was covered up by the stock manifolds or is that leaking as well. I am not sure if the headers themselves are letting more normal noises through or whether they are leaking. Any tips for finding whether this is a leak or normal noises?

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Acerbus · 10-10-2009, 03:16 PM

I used to think that I had an exhaust leak too when I installed my headers. Then I asked around and it seems changing the stock thick iron manifolds for thinner steel aftermarket ones can cause more noise from the combustion reaching the outside world. Even though you have shorty headers, the same principle could apply.

Do you also notice a kind of a hissing sound when you accelerate?

J2L06GT · 10-10-2009, 04:12 PM

I have JBA shortys and have not had any leaking or "header ping"
noise from thinner metal, been on for 2+ years.
If you have a 3-4ft piece of rubber hose, you can use it like a
stethoscope in one ear to isolate the location of noise.

Blair · 10-10-2009, 04:21 PM

Quote:

Originally Posted by Acerbus

I used to think that I had an exhaust leak too when I installed my headers. Then I asked around and it seems changing the stock thick iron manifolds for thinner steel aftermarket ones can cause more noise from the combustion reaching the outside world. Even though you have shorty headers, the same principle could apply.

Do you also notice a kind of a hissing sound when you accelerate?

I do notice a hissing sound, I figured that was the exhaust gas seeping past the leak. When I start the car cold, there is a tick tick tick that goes away after 20-30 seconds. Then the only other noise I hear after the car warms up is when I get on the gas the hissing and ticking noise comes back.

Blair · 10-10-2009, 04:25 PM

Quote:

Originally Posted by J2L06GT

I have JBA shortys and have not had any leaking or "header ping"
noise from thinner metal, been on for 2+ years.
If you have a 3-4ft piece of rubber hose, you can use it like a
stethoscope in one ear to isolate the location of noise.

I tried the hose trick, but didn't hear anything around the headers where they attach to the cylinder head or the H pipe joint. I also held my hand in the same places to try to feel for airflow, but could not feel anything. Although it was a little had to do as the radiator fan was on. Also, I could not see any soot around the gaskets or visual evidence of a leak.

J2L06GT · 10-10-2009, 04:47 PM

You can hear it while outside of car, correct?
If only inside while driving, do you have that noise
enhancement tube that runs from intake to cabin
thru firewall, any chance that could be picking up noise,
never seen any info on how it works.

Simon1 · 10-11-2009, 12:00 PM

Check the clearance on the passenger side between the header and the engine bay/frame wall. Mine was so close it looked like it was touching. It would hit under hard left turns. New motor mounts fixed the problems.

If it's an exhaust leak you should be able to hear it pretty good and pinpoint where it comes from. If I were to guess I would say it's probably where the H pipe hooks up to them. It tricky to get them just right.

Whatever you, figure out exactly where your leak is from first, then fix it. Tightening things beyond specs could yield a broken bolt.

jgorm · 10-12-2009, 11:54 AM

I have JBA shorties on my 02. They leak all the time. Mine had a cracked seam on the passenger side. Once it leaks for a little bit it will blow out the gasket and you will need to install new ones. It might have already burned thru and thats why tightening them does not help. I would find exactly where they are leaking with the rubber hose trick mentioned above. Rule out the H/X pipe flange too. It needs to be fixed. A header leak will cause issues with the tune.

bigray327 · 10-12-2009, 02:35 PM

+1 fix it now, it will cause performance issues since the O2 sensors will be reading off-nominal values and reporting that back to the computer. A leak downstream of the O2 sensor is OK, but not before.

Note: exhaust leaks usually leave black smudges at the leak point.

Derf00 · 10-12-2009, 03:05 PM

I don't care what a manufacturer says, always replace the gaskets with new ones... Would you ever consider reusing a head gasket?? JBA probably stated that you can "reuse" the old ones to keep people from complaining they didn't include new ones with the headers.

Regardless, the old gaskets have gone through a few heating and cooling cycles and are mated to the old exhaust manifolds. Trying to reuse them is like trying to reuse a condom. You don't.

When you were tightening things down, did you follow the appropriate tightening sequence? Have you double checked the header to X or H pipe fitting? Aside from the header gasket, that's a typcial spot where a leak can occur. Did you check the flatness of the Header with a straightedge before you put it on? In some rare instances the surfaces are not completely smooth. These slight bumps or misalignments are magnified when you tighten everything down.

Put the front of the car up on some ramps (not jack stands). Let the car get completely cold. Triple check you have wheel chocks on the rear wheels, the car is in NEUTRAL (if manual) or Park (if automatic) and the E-brake is up.

Have some you trust and knows what they are doing start the car with you under it. Just let it idle. By doing this, you'll have about a minute to feel around the joints of the header to X/Y pipe to see if that's where they're leaking from. You can have them rev the motor to make it easier to find if it's there but you will have less time before things get to hot.

You can also use soapy water presprayed on the joints before you start the car. Just like a leak in a tire you'll see if there is a leak in the joint. If you don't find anything there, i'm guessing either the Header gasket is leaking or you have a non-flat/warped flange.