I have an 08 z71 silverado w/ 123,450 miles. 5.3l that was just in shop for zero compression in #7 cylinder and very low oil pressure. Chevy replaced all lifters as well as oil pressure manifold. Two weeks later now it's knocking, smoking on startup, 5-10 cranks to start up, and emptied 1/2 a tank of gas in less than 60 miles.
HELP!!!! 08 5.3L knocking, smoking, and guzzling the fuel
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1,507 Posts
I don't think that I would mention that it smelled electrical. I would let them come up with their decision based on the work that they did. Boy it seems to be getting harder and harder to trust your decision and take it to a high priced dealer mechanic.
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1,665 Posts
Geeez
That just sucks
I have been thinking about upgrading to a 2004-2006 Suburban-can get one -150,000 miles or so for $5000-$8000-less once gasoline goes up again
I would like the better brakes-better mpg
but maybe I had better stick with my very reliable 5.7 228,000 miles
My only really complaint is the brakes "aren't great"-otherwise-no complaints
I would be pissed if a low years expensive truck like your 2008-punted like that-especially after dumping time and $$ into it
My condolences
Charlie
That just sucks
I have been thinking about upgrading to a 2004-2006 Suburban-can get one -150,000 miles or so for $5000-$8000-less once gasoline goes up again
I would like the better brakes-better mpg
but maybe I had better stick with my very reliable 5.7 228,000 miles
My only really complaint is the brakes "aren't great"-otherwise-no complaints
I would be pissed if a low years expensive truck like your 2008-punted like that-especially after dumping time and $$ into it
My condolences
Charlie
Thank you. Great thing I bought the extended warranty for full powertrain coverage.
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1,665 Posts
Hey
That was SMART
Did you do it because of the oil pressure concerns -2007 on AFM engines- that some folks have problems with??
Anyone know has GM solved the problem?
And what is the WHY of the problem
It is only in a small percentage of AFM trucks
so it isn't a straight engineering problem-something designed wrong
it must be a "some parts not built to fine enough tolerances" problem
so it happens in a small percentage??
Something about AFM- cylinder shut-down-makes the engines "use oil"
best explanation I have read-here-is the lower pressure in the CC CYLINDER-no intake open-
allows oil past the rings or valve guide seal-
maybe has something to do with the piston being cooler-not expanding since no hot combustion gases??
I'm guessing of course
But PLENTY of manufacturers have managed to get it right
Maybe the old 4-6-8 ENGINES from almost 35 years ago finally did(but they had their problems)
Anyway-SMART MOVE on the extended warranty-that was $1000??? very well spent
A new or rebuilt 5.3 must be $6000+
Of HUGE ASIDE- the 5.7 delivered curbside-is $2100-new motor not rebuilt-genuine GM Goodwrench-presume it was built same place the original were(maybe Mexico-but the one I have works great,so they must build them well)
That was SMART
Did you do it because of the oil pressure concerns -2007 on AFM engines- that some folks have problems with??
Anyone know has GM solved the problem?
And what is the WHY of the problem
It is only in a small percentage of AFM trucks
so it isn't a straight engineering problem-something designed wrong
it must be a "some parts not built to fine enough tolerances" problem
so it happens in a small percentage??
Something about AFM- cylinder shut-down-makes the engines "use oil"
best explanation I have read-here-is the lower pressure in the CC CYLINDER-no intake open-
allows oil past the rings or valve guide seal-
maybe has something to do with the piston being cooler-not expanding since no hot combustion gases??
I'm guessing of course
But PLENTY of manufacturers have managed to get it right
Maybe the old 4-6-8 ENGINES from almost 35 years ago finally did(but they had their problems)
Anyway-SMART MOVE on the extended warranty-that was $1000??? very well spent
A new or rebuilt 5.3 must be $6000+
Of HUGE ASIDE- the 5.7 delivered curbside-is $2100-new motor not rebuilt-genuine GM Goodwrench-presume it was built same place the original were(maybe Mexico-but the one I have works great,so they must build them well)
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7,035 Posts
the reason this AFM is not with all of these engines a problem can be explained by owners using the AFM killer. truck owners are more knowledgeable about their vehicles than your typical car owner..
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5,200 Posts
Right on, j cat.
Another possible reason that comes to mind is tolerances ganging up for future failure. During QA machined parts are tested for a "go" or "no go" tolerance. One example: a rod journal must be small enough to pass the "go" test but too large to pass the "no go" test. I'm not a statistician but with a little thought one can realize that ever once in a while an engine will be assembled with all (or more likely most) of the parts at one end of the tolerance. How often this happens I have no idea.
I have 53,000 on my AFM 5.3. Am I worried? You bet I am. When my tuner gets here the AFM WILL get turned off ASAP. I'm too old for this.
Ted
Another possible reason that comes to mind is tolerances ganging up for future failure. During QA machined parts are tested for a "go" or "no go" tolerance. One example: a rod journal must be small enough to pass the "go" test but too large to pass the "no go" test. I'm not a statistician but with a little thought one can realize that ever once in a while an engine will be assembled with all (or more likely most) of the parts at one end of the tolerance. How often this happens I have no idea.
I have 53,000 on my AFM 5.3. Am I worried? You bet I am. When my tuner gets here the AFM WILL get turned off ASAP. I'm too old for this.
Ted
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