[FIXED] Exhaust Manifold Gasket Installation

Hi.

I am working on my mom's 2003 Hyundai Elantra GLS. The car throws a P0133 DTC that I believe to be the cause of an exhaust leak. The O2 sensor has been replaced several times to no avail. I removed the heat shield and found that one of the exhaust studs had worked it's way out of the head of the engine(image attached). I bought a new stud, tightened it down by hand, and torqued a new nut on at 35 ft-lbs. However after completing another drive cycle, the car has the same DTC. I believe that the exhaust manifold gasket blew out after the stud was gone, so I picked up a new gasket from Hyundai. I am looking for any tips on proper installation of the gasket. Should I check the head and exhaust manifold for warpage? If so, any idea on what an acceptable tolerance is. Is there any prep work that needs to be done to the surface of the head or manifold. I have seen some people online using sandpaper, but I haven't done anything like this before and wanted to get a second opinion before I possibly do any damage. Thanks.

Steve

The answer to your question is yes check for warpage on the manifold itself I've never witnessed the head being a issue on this seal. I put them on dry no sealer to be honest never had a manifold on these really need any machining but I never have had to machine a manifold on the Hyundia or Kia 2.0L. usually I see these codes with a flex pipe leaking or a vacuum leak at the plenum gasket and very rarely a temp sender but more common the flex pipe.
prepping the head and manifold I use a 3M wiz disc and if needed I have applied copper coat on the gasket or acoustic sealer but that only when the head or manifold has been scored deep or if I need to compensate for a small air gap. you can use sand paper but I would rather you be very careful not to let anything go into the head. must stuff exhaust ports with rags to prevent any issues.
Again if you get this thing all back together and still think you have a leak check the flex pipe it can throw a curve ball at ya if your not using a stethoscope to pin point exact source of the leak. good luck I will be following this to see a fix reported .

I will move this thread into the Repair Question Section where it will get more responses.

I would expect a leak at the exhaust manifold to head joint that was sufficient to cause a P0133 to be quite audible, any leak a that point tends to make a distinct put-put-put sound.
As a mentioned by MikeN leaks from flexible couplings and pipe joints are more likely and more difficult to locate. To locate a leak try using a piece of tube as a stethoscope or a strip of paper held close to suspected leaks also works.

If you do tackle the manifold to head gasket don't be surpised if the faces of the manifold for the outer cylinder are slightly out of line with the inner pair of cylinders, this is normal. You shouldn't need to use any jointing compound just tighten the manifold nuts in stages working from the centre outwards.
There are ae number of things that can cause a P0133, it would help a lot if you could post a screenshot of your B1S1 and B1S2 outputs at idle speed and also at 2000 to 3000 rpm when the engine is fully hot.also post STF1 and LTF1 fuel trims under the same conditions.

To take a screenshot on an Android device press power and volume down keys simultaneously.

Hi.

After replacing the exhaust manifold gasket, I still had the same P0133 DTC. After disconnecting my battery and running a drive cycle again, the P0133 disappeared and I had a P0420 DTC instead. So, I think putting the new stud in and replacing the exhaust manifold gasket fixed the issue. I know the car has had the P0420 in the past, so I believe the cat is indeed shot, thus the resulting DTC. Thanks for all your help everyone.