Exhaust manifold

BARB420

MEMBER
2003 NISSAN ALTIMA
125,000 MILES

There is a air leak in my exhaust where my exhaust bolt to my motor.
And I have replace the exhaust manifold gasket and still a blow by out of exhaust manifold.
Also, I can't seem to find where my 2 and oxygen sensor goes.
I had just bought this car for $1500.00 and notice the oxygen sensor was just dangling.

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon,

Both O2 sensors go on the manifold. One above the catalytic converter and one below. I attached a picture with the locations.

https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

You need to remove it again and use a straight edge on the manifold to be sure it is not warped.

Roy

Removal and Installation

REMOVAL
1. Remove engine under cover, with power tool.
2. Disconnect the electrical connector of each heated oxygen sensor, and unhook the harness from the bracket and middle clamp on the cover.

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3. Remove the heated oxygen sensors with Tool.

CAUTION:
Be careful not to damage heated oxygen sensor.
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 inch) onto a hard surface such as a concrete floor; use a new one.

4. Remove the lower exhaust manifold cover.
5. Remove the exhaust front tube.
6. Remove the upper exhaust manifold cover.

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7. Loosen the nuts in the sequence shown, on the exhaust manifold and three way catalyst.
8. Remove the exhaust manifold and three way catalyst assembly and gasket. Discard the gasket.

INSPECTION AFTER REMOVAL
Surface Distortion

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Use a reliable straightedge arc feeler gauge to check the flatness of exhaust manifold fitting surface.
Limit: 0.3 mm (0.012 inch)

INSTALLATION

Exhaust Manifold Sequence
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Installation is in the reverse order of removal. Pay attention to the following.

Tightening Exhaust Manifold Nuts
Tighten the nuts in the numerical order shown, to specification. After tightening No.5, retighten No.1 and then No.3 to specification.

Installation of Heated Oxygen Sensors
Clean the heated oxygen sensor threads with the Tool, then apply the anti-seize lubricant to the threads before installing the heated oxygen sensors.
Oxygen sensor thread cleaner: J43897 -18 J43897 -12

CAUTION: Do not over-tighten the heated oxygen sensors. Doing so may cause damage to the heated oxygen sensors, resulting in a malfunction and the MIL coming on.

Images (Click to make bigger)