Originally Posted by hummerz (Post 311944)

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Exhaust Manifold: All Technical Service Bulletins
Exhaust System - Ticking Noises

Bulletin No.: 08-06-05-008

Date: 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

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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.

Originally Posted by OneBigHummer (Post 313802)

Gents
Well since I bought this little beasty a few weeks ago I just noticed a little ticking sound coming from my motor on the exhaust side a couple of days ago. So under further investigation I found one of the rear exhaust bolt missing and one ready to fall out and the rest loose. WTF!

It seem to me that a lot of people have the same issues with their cast exhaust manifold. What are your thoughts on this issue. :confused:

Originally Posted by Doc Olds (Post 313807)

I think you will be lucky if the bolt is just missing, more than likely it broke off in the head. Many... MANY more instances of broken exhaust bolts than just becoming loose. The intake manifold bolts are the ones that are notorious for loosening up.

Of course the prior owner may have had work done and he/she or some slob might not have properly torqued the exhaust bolts?

Good luck.

Originally Posted by OneBigHummer (Post 313815)

Ok well I think I found out what size they are, 8M x 1.25 by 25 pitch or 30 pitch. This is what I can't find out is the pitch. Still looking!

Originally Posted by Doc Olds (Post 313820)

1.25 is the pitch (the last number for a metric fastener is the length). Example: 8MX1.25X30 is an 8MM 1.25 pitch, 30MM long fastener.

You need to look no further than Figure 11 in Hummerz post.