Knock, Knock, Knock
02-05-2005, 09:24 AM
#1
Staging Lane
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Knock, Knock, Knock Recently purchased My first Gen. 3. '01 GMC 6.0. I have developed an engine knock, and not being familar with Gen. 3, I thought it would be good to get out here and learn an little.
From cold driveway start, sounds great. After a short time a faint knock can be heard at idle. Knock goes away if revved above 1700 RPM. If placed in gear, knock becomes quite loud, but still goes away above 1700. Otherwise runs quite well, no sudden loss of MPG or power.
Pulled rocker covers. Inspected for broken rockers, springs, etc... Checked with torque wrench to insure all were tight to spec. Removed rockers and looked for excessive wear.
The only thing I noticed, may not be A problem. If rocker Is held between the thumb and first finger, so that shaft ends are covered, I can feel movement, or play as I wiggle back and forth using the bolt. This would be play between the rocker and shaft, across the legnth of the shaft. Can find no spec. on how much Is allowable ?? The only play I found while installed was A minimal amount of slide back and forth on the shaft.
If This Is not excessive, I will be checking pushrods for clear oil passages, and/or bends. Then, moving onward to inspect the lower end.
Are there any notable classic problems with this generation SBC's, that I should be made aware of ?? Anyone out there had similar gremlins ??
Thanks, Bob.
From cold driveway start, sounds great. After a short time a faint knock can be heard at idle. Knock goes away if revved above 1700 RPM. If placed in gear, knock becomes quite loud, but still goes away above 1700. Otherwise runs quite well, no sudden loss of MPG or power.
Pulled rocker covers. Inspected for broken rockers, springs, etc... Checked with torque wrench to insure all were tight to spec. Removed rockers and looked for excessive wear.
The only thing I noticed, may not be A problem. If rocker Is held between the thumb and first finger, so that shaft ends are covered, I can feel movement, or play as I wiggle back and forth using the bolt. This would be play between the rocker and shaft, across the legnth of the shaft. Can find no spec. on how much Is allowable ?? The only play I found while installed was A minimal amount of slide back and forth on the shaft.
If This Is not excessive, I will be checking pushrods for clear oil passages, and/or bends. Then, moving onward to inspect the lower end.
Are there any notable classic problems with this generation SBC's, that I should be made aware of ?? Anyone out there had similar gremlins ??
Thanks, Bob.
02-05-2005, 12:33 PM
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Staging Lane
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Knockx3
Originally Posted by vettenuts
There was a TSB on cut o-rings on the oil pickup tube for some Gen III engines. You may want to check Alldata to see if yours might be in that group. Your problems sounds like the correct symptoms.