2005 Chevy Uplander knock on start up....

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The temperature here was 37F this morning, overnight it dipped down into the 20's. When I started it up it knocked for about 7 seconds. I am running Mobil 1 High Mileage 5w30 with a Fram Ultra, a very stout combo so I dont think it would be oil, or filter related. This is the coldest morning we have had this year, so I dont think its a coincidence. Basically it had a knocking noise right after start up. I have never heard this before, it did quiet down but was still barely noticeable as I drove down the street then it went away all together after about a minute. I put in in drive and gave it a very small rev to see if it would present itself but no noise. No noise while driving around town this morning either. What part could cause this? I doubt its piston slap since its never made this noise before, and the noise went away in less than 10 seconds.
 

Nick1994

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If it was 37 when you hopped in, and let's say for example overnight it got to 28, the oil in the sump likely hasn't warmed up to 37 yet, so that makes it even colder. I agree that it's probably the notorious GM piston slap. My grandma's low mile Trailblazer has it on a cold start up. So does my mom's Buick Rendezvous. I think it's just the nature of the beast that you probably haven't heard before because of your mild temperatures.
 

gregk24

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Originally Posted By: Nick1994
If it was 37 when you hopped in, and let's say for example overnight it got to 28, the oil in the sump likely hasn't warmed up to 37 yet, so that makes it even colder. I agree that it's probably the notorious GM piston slap. My grandma's low mile Trailblazer has it on a cold start up. So does my mom's Buick Rendezvous. I think it's just the nature of the beast that you probably haven't heard before because of your mild temperatures.
I hope thats all it is. I have piston slap on my Accord, and the noise it makes is quiet in comparison to the noise the Uplander made this morning. Really.
 
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Originally Posted By: The_Eric
Likely piston slap. Cold can really bring it out.
This. You should hear those same vans here up north! It's fine....
 
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It's just GM build quality. Just ask your dealer. You're supposed to live with it. It's the same with burning oil. "It's normal" should be the name tag they wear on their shirts when they talk to owners. There's no need to do any better. You've already made the purchase. But worry not, they will talk to you about things they can do for you that you pay for. That's the part that they are interested in, not complaints that just waste their time.
 

wtd

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Both the 5.7L in my 98 Chevy K1500 and the 7.4L in my 98 Chevy K3500 do this on startup when it's pretty cold out. Wayne
 

gregk24

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After hearing the noise on the Uplander this morning, I took a video of the Accord starting. It went through the same high 20 degree temps last night. Made no abnormal noises, but you can here the piston slap in the background, it has that typical Honda diesel sounding noise. Its done that since I owned it. Just have to wait for it to idle down before you can hear it. The noise from the Uplander that some of you are suggesting is piston slap was much louder and had more of a "knocking" sound too it. Ill have to listen for it tomorrow morning, although it will only be in the 40's tonight. [img]View My Video[/img]
 
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Originally Posted By: Nick1994
I wish I could tell how my car runs on a certain oil or hear if it's noisy on startup. This is all I hear regardless of temperature. I have no idea if my oil runs quieter than another oil! http://youtu.be/bywedxz1pbs
Quiet compared to mine.
 
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Yanno, I'm half wondering if it actually is the filter. I have an Ultra on the 3.4 in the Equinox and it will do a nice upper valve train rattle upon startup when it's cold out. I was leaving out of PA coming back home, it was about 35* on the cold start. Sounded terrible, never noticed it since it was warm mornings here in MS. Now that temps are dropping here, it will do it every cold morning. First time using this filter and never recall it doing that with the M1 or Puro filters when it got to cold mornings... I'll be switching to the OEM PF47 (or larger PF52) here shortly. Needs a change really soon, so no loss of money anyways. Just grinned and bared it till it's time. EDIT: It does have the typical GM slap, but never done it that loud.
 
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