CruelJung
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- Jul 11, 2022
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I have been driving my '08 Yukon XL for nearly four years now, and it has always made a 'ticking' noise on cold startup. This noise subsides within a minute or so, as the engine temperature rises. No CEL or codes. Over the past four years I have been gaining more automotive knowledge and competency, as well as developing a general obsession with this vehicle--how it runs, how it sounds, how my maintenance/repair choices will affect a trajectory towards supercharging one day...
So, I started chasing this 'ticking' noise a few months ago because I noticed an exaggerated form of it under load while driving with the window down. When looking for a busted exhaust manifold bolt, I found that the second-to-rearmost manifold bolt on the passenger side was loose enough to turn with my fingers. There was also soot visible in a few areas above and below the manifold flange. I torqued all 12 bolts to 18 ft. lbs.--noting that all but one bolt were under 11 ft. lbs.--and the result was less noise for less time when cold starting and still noise under load.
Having some free time, last week, I decided to revisit the manifold bolts again because the cold start 'tick' duration seemed to be increasing. Sure enough, the bolts were under the 18 ft. lb. torque spec again and--once re-torqued--the cold start noise level and duration were reduced.
Presuming that the sound (when cold and under load, but dissipating in idle from cold to operating temperature), visible soot, loose bolts (potentially walked out and damaged gasket seal?) point towards an exhaust leak, I am planning to do the following:
1. Replace the current, rusty hardware with ARP header bolts
a. Leaning towards ARP 434-1102 (SS, hex)
b. Considering ARP 434-1301 (SS, stud/nut)
2. In conjunction, replace the exhaust manifold gasket (without removing manifold entirely--i.e., not disconnecting from Y-pipe)
a. Leaning towards OEM (Genuine GM), AC Delco, or Mahle
b. Considering a Remflex gasket or double Remflex gasket to compensate for any warping of the manifold
3. See what happens
a. If the sound persists, I will try to tighten the studs (manifold to Y-pipe).
b. If sound STILL persists after "a.", then I will remove manifold entirely to inspect, replace manifold-to-Y-pipe gaskets, and potentially replace the manifold.
With all of that said, do any of you with experience have some advice for the materials, process, or--for that matter--diagnosis?
So, I started chasing this 'ticking' noise a few months ago because I noticed an exaggerated form of it under load while driving with the window down. When looking for a busted exhaust manifold bolt, I found that the second-to-rearmost manifold bolt on the passenger side was loose enough to turn with my fingers. There was also soot visible in a few areas above and below the manifold flange. I torqued all 12 bolts to 18 ft. lbs.--noting that all but one bolt were under 11 ft. lbs.--and the result was less noise for less time when cold starting and still noise under load.
Having some free time, last week, I decided to revisit the manifold bolts again because the cold start 'tick' duration seemed to be increasing. Sure enough, the bolts were under the 18 ft. lb. torque spec again and--once re-torqued--the cold start noise level and duration were reduced.
Presuming that the sound (when cold and under load, but dissipating in idle from cold to operating temperature), visible soot, loose bolts (potentially walked out and damaged gasket seal?) point towards an exhaust leak, I am planning to do the following:
1. Replace the current, rusty hardware with ARP header bolts
a. Leaning towards ARP 434-1102 (SS, hex)
b. Considering ARP 434-1301 (SS, stud/nut)
2. In conjunction, replace the exhaust manifold gasket (without removing manifold entirely--i.e., not disconnecting from Y-pipe)
a. Leaning towards OEM (Genuine GM), AC Delco, or Mahle
b. Considering a Remflex gasket or double Remflex gasket to compensate for any warping of the manifold
3. See what happens
a. If the sound persists, I will try to tighten the studs (manifold to Y-pipe).
b. If sound STILL persists after "a.", then I will remove manifold entirely to inspect, replace manifold-to-Y-pipe gaskets, and potentially replace the manifold.
With all of that said, do any of you with experience have some advice for the materials, process, or--for that matter--diagnosis?
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