01 silverado 4.8 knocking - The 1947 - Present Chevrolet & GMC Truck Message Board Network

allaboutchevelles · 02-12-2012, 10:24 PM

Hey guys, Im from the 60-66 C10 forum room mostly. I have been having problems with my DD for a while now. Its a 01 silverado ext cab 2 wheel drive with the 4.8 engine. For the last about 2 years every time I start it after sitting for several hours the motor has a bad KNOCKING sound. It goes away right after the motor warms up for about 3 or 4 minutes. Ive heard alot of problems with this and chevrolet says it will not hurt anything. The truck only has 95,000 miles on it with regular oil changes every 3500 miles. What is causing this and is there anything to do to fix it??? Thanks!!

usmcchevy · 02-12-2012, 10:42 PM

Sounds like Cold Start Knock. I've had them do it when the temp drops below 50, but in the summer they are fine. Sucking a bottle of seafoam through the brake booster hose seems to help it short term, but no long term fix. Does the oil press fluctuate while its knocking?

463 · 02-12-2012, 10:48 PM

Gm calls it piston slap. I hope it has a WIX 51522 or a AC DELCO PF46 oil filter.

clinebarger · 02-12-2012, 10:59 PM

Cold piston slap on Gen III engines is normal, I had a 97 Corvette LS1 that would sound like it was coming apart untill it warmed up.

If it takes a little while to build oil pressure & the rods are rattling, The O-ring on the oil pump pick-up needs to be changed.

allaboutchevelles · 02-12-2012, 11:21 PM

Thanks for replys guys. The oil pressure stays way up the whole time like on 60. I normally run a AC delco filter or a wix from carquest. not sure of the part numbers of the filters.

gregory5000 · 02-13-2012, 09:32 PM

Yep like the others said it is a common thing. My truck does it. You are also changing your oil too much. It is not hurting anything, but it is not helping anything either, just hurts your wallet.

spudz · 02-13-2012, 09:47 PM

Normal. Its piston slap.

**truckdude239** · 02-14-2012, 09:25 PM

its normal always runa good brand filter wix ac delco or purealtor

02-12-2012, 10:24 PM	#1
allaboutchevelles Registered User Join Date: Dec 2010 Location: sanford nc Posts: 499	01 silverado 4.8 knocking Hey guys, Im from the 60-66 C10 forum room mostly. I have been having problems with my DD for a while now. Its a 01 silverado ext cab 2 wheel drive with the 4.8 engine. For the last about 2 years every time I start it after sitting for several hours the motor has a bad KNOCKING sound. It goes away right after the motor warms up for about 3 or 4 minutes. Ive heard alot of problems with this and chevrolet says it will not hurt anything. The truck only has 95,000 miles on it with regular oil changes every 3500 miles. What is causing this and is there anything to do to fix it??? Thanks!! Attached Images __________________ 69 chevelle malibu, 64 C-10 shortbed

02-12-2012, 10:42 PM	#2
usmcchevy Has more rust than truck... Join Date: Apr 2005 Location: Ivanhoe, MN Posts: 2,421	Re: 01 silverado 4.8 knocking Sounds like Cold Start Knock. I've had them do it when the temp drops below 50, but in the summer they are fine. Sucking a bottle of seafoam through the brake booster hose seems to help it short term, but no long term fix. Does the oil press fluctuate while its knocking? __________________ 1972 Custom/10 SWB, 4.8/4l80e Build thread LSx Swap FAQ index

02-12-2012, 10:48 PM	#3
463 Registered User Join Date: Nov 2007 Location: Sask Canada Posts: 1,666	Re: 01 silverado 4.8 knocking Gm calls it piston slap. I hope it has a WIX 51522 or a AC DELCO PF46 oil filter. __________________ Trueman

02-12-2012, 10:59 PM	#4
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: 01 silverado 4.8 knocking Cold piston slap on Gen III engines is normal, I had a 97 Corvette LS1 that would sound like it was coming apart untill it warmed up. If it takes a little while to build oil pressure & the rods are rattling, The O-ring on the oil pump pick-up needs to be changed.

02-12-2012, 11:21 PM	#5
allaboutchevelles Registered User Join Date: Dec 2010 Location: sanford nc Posts: 499	Re: 01 silverado 4.8 knocking Thanks for replys guys. The oil pressure stays way up the whole time like on 60. I normally run a AC delco filter or a wix from carquest. not sure of the part numbers of the filters. __________________ 69 chevelle malibu, 64 C-10 shortbed

02-13-2012, 09:32 PM	#6
gregory5000 Registered User Join Date: Feb 2010 Location: elora tn Posts: 121	Re: 01 silverado 4.8 knocking Yep like the others said it is a common thing. My truck does it. You are also changing your oil too much. It is not hurting anything, but it is not helping anything either, just hurts your wallet. __________________ 2001 GMC 2WD, 1998 Chevy K2500

02-13-2012, 09:47 PM	#7
spudz Registered User Join Date: Oct 2005 Location: Branchville SC Posts: 1,647	Re: 01 silverado 4.8 knocking Normal. Its piston slap. __________________ 2004 z71, 96 z71 on 38s, 88 Chevy k5 blazer, 4in lift. 84 swb project, 82 SWB project , 84 chevy 4x4 lwb project, 88 Jimmy beater/highschool ride. 79 c30. 99 tahoe 4x4 project. and a bunch of parts trucks..

02-14-2012, 09:25 PM	#8
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,217	Re: 01 silverado 4.8 knocking its normal always runa good brand filter wix ac delco or purealtor __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube



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