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Old 12-01-2007, 06:55 AM
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Gen III SBC cold knock basicly fixed...!

I had the same issue I have read about many others having with the 4.8, 5.3 and the 6.0 with the cold start up knock... When first cranked and pull out of the driveway you get a knock for a few seconds with some of these engines... Mainly the pre 02 models...

Well just recently I had a GM tech overhaul my 4l60e trans in my 99 Silverado (168K miles) so I could pull our 26' Fleetwood lite travel trailer... I knew the the trans was starting to have issues from the way it was shifting and had a shudder on take off in 1st... It was built with all new hard parts for a Corvette including a brand new valve body from GM... I also had him change the rear gear to a 3.73 and add an Eaton locker (total cost with labor was $1700 turn key for both trans and rearend)

Anyhow in the process the GM tech had to update the ECU for the gear change plus any update that GM added and ever since this was done my cold knock is gone... Everyone was saying it was the short skirt pistons which caused a piston slap till they warmed up... No it was a cold fuel trim issue that GM has figured out from what I can tell... Also my mileage went from 19-20mpg on the highway to 20-21mph highway... Pulling the 5000lbs travel trailer it still gets 11-12mpg in drive and on level ground no wind OD is no problem...

But the cold knock is no more... Also note NO change of oil or fuel brands or anything else...

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Old 12-01-2007, 07:20 AM
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Good for you. My cold knock was fixed by replacing the pistons.

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Old 12-01-2007, 07:41 AM
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Wow, trans overhaul, gear change and a locker for $1700!!!! Man did you get the deal of the year!
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Old 01-04-2008, 08:37 PM
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1700.00!! thats a deal! where are you from bumpstick?
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