New to me truck makes a tap at startup. Any ideas?

[Riptide Outdoors]

I just bought a 2011 1500 with the 6.2l 168k miles and its making a tapping noise at startup, almost like tapping your phone screen with your nail but a little more high pitched. The noise starts a few seconds after the truck starts and is pretty loud for about 20 seconds then slowly fades away. Its pretty faint once at temp and it goes almost completely away once its been at temp for roughly 10 minutes. I had a 2008 5.3 with 305k miles and it had lifter tick but this isnt he same noise, but also a different engine so it could be the lifters and just a different sound.

 

Its not exactly cold here, mid 70s to low 80s in the mornings but thats still cool for an engine so my assumption was piston slap cause i know thats a common issue with these trucks, but wanted to get some other opinions on it. Truck runs and drive fine and everything else seems to be working but i just want to make sure im not ignoring the start of a larger problem. I tried some top engine cleaner and did a tank with techron cause i saw that recommended in some other thread but i didnt notice any difference after either one.  

[richard wysong]

Exhaust leak at the exhaust manifold would be a common thing with those symptoms, look for broken/missing bolts, you will probably have to inspect through the wheel wells

[newdude]

Couple possibilities come to mind.

 

1st being cold start catalyst light off.  They adjust the timing of the engine to essentially allow combustion right in the manifold to light the cats off so they can do their job.  - temp.xml (nhtsa.gov) READ HERE.

 

2nd, you've got a broken exhaust manifold bolt somewhere.

 

3rd albeit a slim chance.  Oil pump.  There was a production window with oil pumps that would cause a tick on start up or some time after 10-15 minutes of run time, build window is 4/1/11 to 11/1/11.  "PIP4978E: Tick Noise Cold or After 10 To 15 Minutes Of Engine Run Time It May Also Happen After A Coast Down At Operating Temperature **DO NOT REPLACE LIFTERS** - (Feb 6, 2012)" 

 

Most of the oil pump trucks "should" have been fixed at lower mileage as most of the ones GM found back then had under 6,000mi on them. 

Edited September 4, 2024 by newdude

[Riptide Outdoors]

3 hours ago, newdude said:

Couple possibilities come to mind.

 

1st being cold start catalyst light off.  They adjust the timing of the engine to essentially allow combustion right in the manifold to light the cats off so they can do their job.  - temp.xml (nhtsa.gov) READ HERE.

 

2nd, you've got a broken exhaust manifold bolt somewhere. 

would either of these speed up with rpm’s? I let it warm up for a minute or two before driving but there’s still the noise a little and when I’m accelerating the sound speeds up. Sorry if that’s a dumb question 

[richard wysong]

yes they both will increase with the rpms

[PunchT37]

Sounds like broken exhaust manifold bolts to me.

[newdude]

2 hours ago, Riptide Outdoors said:

would either of these speed up with rpm’s? I let it warm up for a minute or two before driving but there’s still the noise a little and when I’m accelerating the sound speeds up. Sorry if that’s a dumb question 

 

 

The exhaust would, yes.  The cold start heating deal wouldn't keep going after the 50 seconds or so it lights the cats.  

[Jworks]

I've got that ticking sound at startup also (2011 GMC, 5.3 engine).  It seems to go away after its driven a few miles.  By that time the engine is at normal temp. Wife says she can hear it even then.  I don't know about that.  But I have high frequency hearing loss.  Mine could be the exhaust manifold - as some have said.  But it "sounds" metallic to me.  I'm no expert, just a truck owner.  I would surely hope mine is exhaust and not lifters.  I've heard both are common to these engines.

[OnfroiTraverse]

On 9/4/2024 at 9:07 PM, Riptide Outdoors said:

I just bought a 2011 1500 with the 6.2l 168k miles and its making a tapping noise at startup, almost like tapping your phone screen with your nail but a little more high pitched. The noise starts a few seconds after the truck starts and is pretty loud for about 20 seconds then slowly fades away. Its pretty faint once at temp and it goes almost completely away once its been at temp for roughly 10 minutes. I had a 2008 5.3 with 305k miles and it had lifter tick but this isnt he same noise, but also a different engine so it could be the lifters and just a different sound.

 

Its not exactly cold here, mid 70s to low 80s in the mornings but thats still cool for an engine so my assumption was piston slap cause i know thats a common issue with these trucks, but wanted to get some other opinions on it. Truck runs and drive fine and everything else seems to be working but i just want to make sure im not ignoring the start of a larger problem. I tried some top engine cleaner and did a tank with techron cause i saw that recommended in some other thread but i didnt notice any difference after either one.  




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Sounds like broken exhaust manifold bolts to me.