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I'm surprised to hear you had to change both, as it was usually just the right side that had problems. Being that it was replaced before, you could try complaining to Nissan's customer service hotline ( 1-800-NISSAN-1 ) and perhaps they help you out. As far as having better flow, I have not heard anything about that and wouldn't expect to have any issues due to a differance in performance with an older design, left side manifold (which I'm not sure has even been redesigned). Negative consequences of running with a cracked manifold are potentially burning a valve and causing inaccurate readings by the O2 sensor, as well as potential check engine light triggerings. Anyway, there were enough of them to warrant this service bulletin:
Classification:
EM01-003
Reference:
NTB01-038
Date:
May 22, 2001
FRONTIER AND XTERRA RIGHT-HAND EXHAUST MANIFOLD CRACKED
APPLIED VEHICLES:
1999-2001 Frontier (D22)
2000-2001 Xterra (WD22)
APPLIED VINs:
Frontier - vehicles built before 1N6ED27Y51C383612
Xterra - vehicles built before 5N1ED28Y01C576621
APPLIED DATES:
Frontier And Xterra - vehicles built before April 6, 2001
APPLIED ENGINE # :
Engines built before VG33-653777
SERVICE INFORMATION
If an Applied Vehicle has one of the following symptoms:
^ A ticking or exhaust noise from the right-hand exhaust manifold area.
Or if a cracked right-hand exhaust manifold is discovered during unrelated service 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 Service Procedure provided in this bulletin to diagnose the condition, replacing the right-hand exhaust manifold and related parts as described.
SERVICE PROCEDURE
Diagnosi5:
1. With the engine running, verify that the source of the noise is 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.
CAUTIONS: 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 (refer to the PARTS INFORMATION section of this bulletin for details).
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 (refer to the PARTS INFORMATION section of this bulletin for details).
3. Install the replacement manifold with a new gasket onto the head. See Figure 2B for tightening sequence of manifold nuts. See Figure 1 shown 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. Test-drive the vehicle to verify the ticking or exhaust noise has been eliminated.
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FYI: Alldata gives a replacement time of 1.6 hours for the right side and 2.8 hours for the left. Manifold torque at 23 ft./lbs.
Last edited by smj999smj : May 7th, 2006 at 09:03 AM.
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