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Central Illinois | I've got an '06 Avalanche w/8.1. It's got 49,000 on it and hasn't been used hard. Starting this fall as it got cold over night it started to rattle in the morning when started--under 30deg.
The first noise would be upper valve train which quiets down quickly followed by a deeper knock which lasts for a minute or so. It's carrying 40psi cold. This fall I had synthetic in it then switched back to Cen-Pe-Co just a few days ago. Drove it this morning the the valve train rattle is gone on startup but the deeper knock is still there--albeit not as bad.
It runs just fine and it's oil consumption is minimal.
Has anybody else had experience with this? A friend said these motors have floating wrist pins allowing some cold knock. Sure hope it's not a rod or main.
TIA | |
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8.1 cold start knock
