Herd knocking for the first time tonight?.?.?

[ryan04z71]

04 z71 Tahoe, 159,*** miles. Just got this truck maybe a month ago. Changed oil with Mobil 1 full syn and a bottle of lucas, the same week I got it. Maybe 800 miles on oil.
I parked the truck 5 days ago. Started it up tonight and about 30-40 seconds after startup I start to get a slight knock. (Nothing crazy loud but could be, to me, clearly heard.) Gave a touch on the gas, got a little louder and faster (obviously lol)
So I immediately shut it down, curse a few times, patted her on the dash, checked oil level (good) and fired it back up..... And..... No more knocking?.?.?.?.?.
We've had some cold nights, but nothing to crazy.
So am I thinking to much into it and it just took a minute for oils to get going good? Or....... :-/


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[ccapehartusarmyINF.(ret)]

usually the knocking is from your lifters and i dont hear mine unless its been about 3000 miles on the oil and i hear knocking immediatly when the vehicle starts and it goes away after about 20 seconds when the oil has gotten were it needs to go

 

[ryan04z71]

I was showing good oil pressure. Forgot to mention that as well

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[Resident Psycho]

Correct 100%. Phenolic pistons need to expand into the cylinder sleeve (These GENIII LS based motors use sleeves) until they warm up (expand) you will have this "knock sound" completely normal. The pistons were made a little loose and once they warm up it goes away, usually within 10-20 seconds. If it knocks for a few minutes then you should have it checked out.

 

[ryan04z71]

What a relief!! It only did it for a short time. Then as I said, when I started it back I didn't hear anything.

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[Mechahead]

Yeah, mine does that when its cold out. Drives me nuts, but its normal so I have to get used to it.

 

[ryan04z71]

Definitely glad to be hearing this! Was not looking forward to replacing the engine... Tho..... I did go straight to wondering what it would take to drop a 6.0 in her lol!!

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[605Jake123]

Boy am i glad i found this! I have been also having a knocking noise right at start up for a couple weeks now and freaking out thinking it was something that was going to be very expensive. it has been very cold and I am now due for an oil change so hopefully after i get my oil changed and it warms up this noise will stop at start up.

 

[JonnyTahoe]

I'm wondering if these engines made that knocking when they were brand new, I would not think anyone would of bought the "cold engine" theory. I did not buy mine new so I dont know but if It was happening on the new one's I would think the Dealers would be getting alot of them back.

 

[YukonXLPerk]

I have owned 2 with the 5.3 and they both knocked at start up. It is hard to hear inside the cab. Have a friend start it while you are standing next to it. You will def hear the noise.

We also have owned a 94 burban, 96 yukon, 00 burban, and a 09 silverado....they all did it.
The 94 suburban though, sounded like a cylinder was trying to fight its way out of the block! It did that for 100k miles!