The 2 second rattle is a feature of the V6. Mine does is on occasions, no problems so far.

 

I notice a LGZ start up rattle most only in winter when it's cold or the truck has sat unused for several days. I also believe it is some sort of oil drain back issue but exactly where seems difficult to say. It could be the phasers . . . a good culprit. But I think there is at least one timing chain tensioner that operates on oil pressure.

The LFX also has a start up rattle and seems ok even after thousands of starts.

Dealers will say "it's normal" and apparently is for these modern marvel engines. ::chevy::

 

I notice a LGZ start up rattle most only in winter when it's cold or the truck has sat unused for several days. I also believe it is some sort of oil drain back issue but exactly where seems difficult to say. It could be the phasers . . . a good culprit. But I think there is at least one timing chain tensioner that operates on oil pressure.

The LFX also has a start up rattle and seems ok even after thousands of starts.

Dealers will say "it's normal" and apparently is for these modern marvel engines. <img src="http://coloradofans.com/forums/images/smilies/icon_chevy.gif" border="0" alt="" title="" class="inlineimg" />

I will agree with you on cold mornings, first starts after a day or more of sitting, warm starts no noise....apparently someone claims to have had success with using 10w-30 oil instead of the manufacturer recomended 5w-30 and his explanation is the 10w viscosity is different than the 5w at cold start and he claims it worked for him, has anyone tried this science experiment?

 

In all honesty I'm not prepared to turn my new 2018 CCLB into a Guinea Pig with the 10w-30 oil test, but me putting this out there I'm hoping to hear from someones experience if they did try it, basically putting in 10w-30 should coat metallic parts heavier I would assume although once oil reaches engine operating temp doesnt act less viscous anyway? Wouldnt it all return to the pan the same 5w or 10w......inquiring minds.....

 

Maybe. . . but ease of flow when cold should be better with 5W-30 than with 10W-30 . . . and even better with 0W-20 as GM specifies for below 20F temperatures.

The "cling" or coating characteristic you speak of is another aspect of oil. Basically film strength.

There is an article and study that was posted here awhile ago. A lot of info so sit back for a very long and detailed read if you want to know about oil and comparisons to each other.



https://540ratblog.wordpress.com/

 

Had a old GMC Jimmy with the 4.3. It had a similar rattle with cold starts and the dealer switched the type of oil filter that they claimed had a check valve. Seemed to work, would this help?

 

An anti-drain back valve on the filter makes sense to keep the filter loaded with motor oil after ignition is turned off but what about the motor oil that is needed to operate the phasers on the camshaft timing gears, the rattle appears to be in the phasers for the camshaft timing gears so I'm not sure if keeping the oil filter at the top of the engine populated with motor oil will prevent the phasers from unloading its motor oil.

 

Here is a good video of my truck making the 2 second rattle after sitting all night. Hope it’s normal

https://youtu.be/feuPm09Fur0

 

My wife’s ‘17 Acadia with the 3.6 does the same rattle when you first start it up when cold. I thought it was normal.

 

There is a lot of speculative rattle on this topic by many but no one has found anything definitive. To this point it is claimed to be normal by GM and no wide spread failure have been happening.

If you stop and listen to many of today's engines there are many un natural unexplained noises today that present themselves. Most are just part of the many complicated systems the MFG's are employing to meet the new regulations.

My old 2.0 used to sound like a ball bearing falling into a can when I shut it off and when I started it the air intake noise was horrendous. I found out later it was just part of the emission package at start up and normal. I expect we will see more of this odd stuff as we go along.

I noted my Wife's Acadia also does the rattle in the cold with a canister filter that is sitting up. The truck does it with a cartage.

 

My truck is still doing it every time it sits overnight but no issues so far so it must not be hurting anything. I'm not worried about it at all anymore. Many are reporting this so i think of it as a feature more than an issue. lol

 

Does this sound normal to you guys? Cold start ticking is what I’m calling it but just bought a used 2018 Colorado Lt with the V6 about a month ago Only has 15,000 miles and seem that this sound is new or should say new my ears never noticed it till it’s been could out

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Does this sound normal to you guys? Cold start ticking is what I’m calling it but just bought a used 2018 Colorado Lt with the V6 about a month ago Only has 15,000 miles and seem that this sound is new or should say new my ears never noticed it till it’s been could out

https://youtu.be/LzBWK9BffDk


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It sounds like normal fuel injector ticking to me. Nothing out of the ordinary.

 

Hey Thanks for the video! I wish I would have seen this before I posted about this. In any event my truck makes this same noise with only 600 miles on it. Two other strange noises is when backing up with the wheel turned to the right makes a clicking sound and also when driving at slow speeds going over slight bumps heard from the driver side sounds like a dried urethane bushing or a squishing type sound from the vehicle shock im guessing? Anyone else? Thanks!

 

I would say try not to focus too much on every little noise. These are trucks so they won't be as smooth and quiet as a Lexus. Trucks are just going to be clunkier no matter which one you get...body on frame, 4 wheel drive, etc. If it helps, put on some good music, crank up the volume and enjoy the drive! >

 

You'll find the same discussion on other vehicle makes and models with GDI engines.
It was enough to convince me it's just a normal part of GDI's high-pressure injectors.

20,000 miles later it sounds exactly the same as it was when I asked here, and the duration is 100% consistent:

https://www.coloradofans.com/forums...5-2nd-gen-engines-technical-discussion/346113-2017-3-6l-squeaky-cold-start.html