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I was checking my work after an oil change on Saturday afternoon when I found exhaust leaks where the header flange mates with the first exhaust tubing flange, just upstream of the O2 sensor, on both left and right sides. I observed vapor escaping the joint and felt the leaking air with my hand. I suspect both sides have been leaking for a while due to the carbon-type discoloration at the joints. The welds appear to have held, but it appears the gaskets at each joint have failed. Left (Driver's) Side Right (Passenger's) Side
Is fixing this as "simple" as replacing the gaskets? Is this to be expected on a car that lived its first ~3yrs in snowbelt states? It seems odd to me that both sides have failed in the same spot, with apparently equivalent carbon buildup.
I just got the car (2011 with stock exhaust) and am trying to figure it out. I have never had to deal with an exhaust leak at a joint like this before - my two previous experiences have been a corroded muffler (corrected by welding on a replacement) and a minor weld imperfect/leak at a resonator (corrected by touching up the weld).
I had the same leaks, albeit with aftermarket header and exhaust. Chances are it is from installation and the exhaust not being aligned well, since both sides failed. Loosen up the exhaust, get new gaskets, and start snugging the exhaust down loosely at first. Tighten it from the headers first and work your way back. I had to loosen most of my exhaust and realign it, but it seems to have worked. Since your exhaust is oem, new oem gaskets should work. You can use aftermarket if you prefer.
You may also want to try Remflex #8019 crush style 2 bolt flange gasket. Trust me... I went through about 6 different gaskets before I found these. I swear by them now.
Also, might not be a bad idea to pick up some new nuts for the bolts. They are oblong locking nuts that may be rounded after being taken off a few times (they may not stay torqued).
I had the same leaks, albeit with aftermarket header and exhaust. Chances are it is from installation and the exhaust not being aligned well, since both sides failed. Loosen up the exhaust, get new gaskets, and start snugging the exhaust down loosely at first. Tighten it from the headers first and work your way back. I had to loosen most of my exhaust and realign it, but it seems to have worked. Since your exhaust is oem, new oem gaskets should work. You can use aftermarket if you prefer.
Okay, good advice, thank you. So are we both suspecting that this car had an aftermarket "cat-back" exhaust installed at some point, then when the OEM system was re-installed it was not aligned correctly at these joints? I have a hard time believing a pristine factory installation would fail on both sides simultaneously.
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Thanks JoeZ and Kyle for gasket info, I will investigate. I will plan to replace bolts, nuts, and gaskets. I have plenty of PB Blaster on hand, but who knows what it will take to get those corroded fasteners broken free. This sort of stuff is so much easier on a lift, so am considering taking it to a shop instead of wrestling it at home.
My new O2 sensors came without shields. Not sure when they changed that. I bought oem (Bosch?... can’t remember brand) based on part numbers. So those are newer O2s.
You also don’t necessarily know that they failed at the same time, but if one side is not lined up correctly, chances are the other side isn’t since that mid pipe is all connected. If it was removed and replaced with the old gaskets, that would explain why they both leaked, since they crush during initial install.
Look around for markings like JoeZ stated. The car may be able to hint as to its past.
My new O2 sensors came without shields. Not sure when they changed that. I bought oem (Bosch?... can’t remember brand) based on part numbers. So those are newer O2s.
You also don’t necessarily know that they failed at the same time, but if one side is not lined up correctly, chances are the other side isn’t since that mid pipe is all connected. If it was removed and replaced with the old gaskets, that would explain why they both leaked, since they crush during initial install.
Look around for markings like JoeZ stated. The car may be able to hint as to its past.
Good point, if one side was off, it could/would torque the other. I appreciate the nuance. I will look around more closely. This detective work is fun.
Originally Posted by Joe Z
Denso OE or Lexus OEM would look like the below..
Okay, so clearly mine has either newer or modified original O2 sensors.
Thanks for photo.
My right/passenger-side O2 sensor. Clearly no shield/sink. (sorry for focus)
Found this photo from the JoeZ/PTS catback install megathread here from several years ago.
Following up...replaced gaskets, bolts, and nuts yesterday. There were no signs of scoring on the O2 sensors, everything had the same rusty patina, and the rest of the exhaust sections were well-aligned and appeared untouched. So I think this was a simple lifetime fatigue failure of the gaskets.
Based on discussion here, it seems the O2 sensor styles were different over the years, or at least for 2011.
The exhaust note is much less agricultural now. Thanks to all for the timely help. :-)
03-30-20, 12:23 AM
Exhaust Leak: Root Cause and How to Fix?
