6/24/2009
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Figure 1
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Figure 2A
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Figure 2B
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1999-2001 Frontier and Xterra Right-Hand Exhaust Manifolds Cracked in VGS33E Engines
A ticking or exhaust noise has been reported coming from the right-hand exhaust manifold area of some 1999-2001 Nissan VGS33E engines.
If a cracked right-hand exhaust manifold is discovered when the exhaust heat shield is removed, a replacement right-hand exhaust manifold is available to correct the incident.
If one of these symptoms should occur, use the following to diagnose the condition, replacing the right-hand exhaust manifold and related parts as described.
SERVICE PROCEDURE
Diagnosis:
1. Installers should verify the source of the noise with the engine running that it is coming from the right-hand manifold area.
2. If the noise is coming from the right-hand manifold area, remove the heat shield and inspect for cracks between the #1 and #3 ports on the manifold.
Repair:
1. Separate the catalyst from the right-hand exhaust manifold and remove it to allow for clearance.
Caution: The nuts that attach the catalyst to the exhaust manifold have a self-locking design and require some effort to remove. Apply penetrating oil to the threads and allow it to soak in before attempting to remove the nuts.
Use a tight-fitting six-point socket to avoid rounding off the corners of the nuts during removal. If any of the nuts or studs are damaged during removal, replace them as needed.
2. Remove the exhaust manifold from the head (See Figure 2A for loosening sequence of manifold nuts). NOTE: If any of the nuts or studs are damaged during removal, replace them as needed.
3. Install the replacement manifold with a new gasket onto the head. See Figure 2B for tightening sequence of manifold nuts. See Figure 1 for manifold nut torque specifications.
4. Re-attach the catalyst to the exhaust manifold. NOTE: Ensure that all bolts securing the manifold and heat shields are installed and are torqued to the specifications shown in Figure 1.
5. Installers should test-drive the vehicle to verify the ticking or exhaust noise has been eliminated.
Some or all of this information was provided by the Automotive
Parts Remanufacturers Association (APRA). For more information on
technical bulletins available through APRA call 703-968-2772 or visit www.AutoBulletins.com.