Exhaust System - Ticking Noises
Bulletin No.: 08-06-05-008Date: October 21, 2008
Subject:
Exhaust Tick Noise, Exhaust Manifold (Replace Gasket, Bolts and Manifold as Necessary)
Models:
2006-2009 HUMMER H3
with 3.5L or 3.7L Engine (VINs 6, E - RPOs L52, LLR)
Condition
Some customers may comment on a tick or noise coming from the exhaust. Upon further inspection, the technician may discover a leaking exhaust manifold gasket. In some cases the leak may be accompanied by a broken manifold bolt.
Correction
Replace the exhaust manifold gasket and bolts (new part number) following the Exhaust Manifold Replacement procedure listed in SI. Be sure to follow the torque sequence procedure and tighten the bolts to a MAXIMUM of 20 Nm.
The exhaust manifolds are ductile; they must be allowed to move with heat expansion and cooling contraction. The manifold bolt holes are larger than the bolts to allow manifold movement. If the bolts are overtightened or torqued unevenly, the manifold movement will be restricted, which may result in manifold cracking or bolt breakage.
In rare cases, the exhaust manifold may also be cracked most likely between exhaust runners # 4 and # 5.
DO NOT replace the exhaust manifold if it is not cracked. Often the exhaust manifold will appear warped when unbolted this condition is NOT a reason for exhaust manifold replacement.
DO NOT replace the exhaust manifold if a bolt is broken and/or the gasket is leaking.
DO NOT remove the cylinder head to extract a broken exhaust manifold bolt. Follow the bolt extraction procedure found in this bulletin.
Broken Bolt Extraction Procedure:
Important:
Always use penetrating lubricant when removing studs or nuts. Do not exceed 150 rpm tool speed when removing or replacing the three exhaust flange gasket studs or nuts. The studs are a thread lock design, and damage to the stud or manifold will occur if 150 rpm tool speed is exceeded.
Remove all unbroken manifold bolts and flange nuts.
1. Remove the exhaust manifold.
2. Using a center punch, dimple the center of the broken bolt.
3. Using a right angle air drill and a 5/64 bit, drill a hole through the broken bolt.
4. Spray penetrating lubricant through the drilled hole so that the bolt threads are saturated from the back side.
5. Heat the cylinder head flange area around the bolt.
6. Using a bolt extractor, remove the broken bolt from the head.
Parts Information
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer