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Piston Slap...A couple questions about my swap options

av-summit

Full Member
Joined
Oct 30, 2012
Messages
45
So I have pretty bad piston slap in my 2007 LC9.  At first I was going to try and identify the bad piston, drop the pan, pull the head, and push the piston out the top and replace.....but I cant determine which piston it is.  The sound resonates to much through the block.  Even tried powering down coils to see of I could tell that way.......anyway I digest.  Plan B

Found some motors to swap, and yes I have read the threads on the swaps, but still I still need answers/opinions, so here we go..

    Option 1) $500
    Can I go with a 2003 5.3 and get away with it?  I know the reluctor wheel would have to be
    changed.  What would the computer do with no DOD (they didn't have DOD back then right?)

    Option 2) $800
    I am checking on a 2007 5.3.  Would be a straight swap and booooring but honestly for $800 its
    its not bad, and I have two other projects I need to put money into

    Option 3) ~$1000
    I am also checking at the same place on a 6.0.  It will come with the ECM and such.  From what
    I've read, I have to install the knock sensors from the 5.3 and wait for my 4L60 to blow up.  I
    read somewhere the 6.0 had VVT and no DOD which I'l have to deal with?  This true?
       
    Option 4) ~$1000
    Buy option 2 for a straight swap at $800 and slide a cam into it for the extra power I would get
    with option 3

I loooove the idea of the 6.0, but like I said I have other projects that requires my headaches and money.  This is my daily driver.  Tows sleds to the mountains, and the car to the track a handful of times throughout the year.

Any input would be appreciated.  Going to not go to bed now and lay awake thinking about my options! javascript:void(0);  Fun!
 
There really shouldn't be a piston slap issue on the '07's; it was already addressed at that point by making the piston skirts longer.
 
I thought it was a sticky lifter when I bought the truck.  I've had the truck for about three years and it keeps getting worse/louder on cold start ups.  It goes away once the motor start to warm up, but ive noticed that it is taking longer (more temp) for it to quiet. 

 
To me piston slap and a lifter make very different sounds.

Maybe it's an exhaust leak?
 
I thought it was a lifter because the noise only very slight and hard to diagnose at the time when I purchased truck; but has gotten worse since.  Its more noticeable in the winter when it is below zero.  Also when I put in into gear and there is load on the engine; the sound becomes 'way' more pronounced.  Its a piston, not exhaust.  Exhaust is more of a tick.  This is closer to pinging, same as when timing an engine to far advanced.
 
Have you tried a fuel system cleaner gas additive?  Maybe injectors are getting gunked up and take a while to flow well?
 
Yes, twice. GM Upper Engine and Fuel Injection Cleaner. 

The motor still has power, doesn't miss, idles fine and doesn't use oil (any more than it should anyway....stupid DOD)   
 
I wonder if there's a temp sensor issue causing the computer to give it too much spark advance when cold?

Have you tried pulling the injectors/rails and turning the engine over with the injectors still wired to see what their spray pattern looks like?
 
Nope.  I would think the idle would be high or erratic if this was the case. 
 
Isn't the 5.3 known for some degree of piston slap? Mine sounds like a diesel on a cold morning, but settles down in a couple minutes. I was under the impression this was normal to some degree.
 
Coolant temp affects the idle speed and idle air flow, but combination of air temp sensor and coolant temp inputs affect calculated air mass per cylinder stroke and spark advance.
 
The temp sensor is probably just a glorified RTD that GM makes us pay through the nose for.  If thats the case, in my experience, 9.9 times out of 10 they simply fail open.  If they slowly start to fail, it usually isn't a linear process over 2 years, its mostly erratic and short lived.  I would think the pinging would be there all of the time and not retard as I would expect the sensor to be failed open by now.  Also I hope I would get a code for a failed sensor?  Interesting thought though.  I'll look into it to make sure.  Do you know the resistance value or the type element/metal used? 

Air Junky we may have the same problem.  How many miles on your engine.
 
158k on mine. Still runs strong. Doesn't use oil at all unless I'm towing a lot & then it'll use a little. Had a mechanic install a new transmission a while back & he never said a word about any issues he noticed about the engine.
 
Piston slap.had it bad on my 2002 Sierra , ended up with a 2003 engine installed and still running strong.
My 2002 was so noisy at 16k ,noise started after only 5k and took many times back to get a new engine along with help from BBB.
I was told the problem was fixed for 2003.
 
av-summit said:
Can anyone answer the question about the DOD on the earlier 2003 engines?

Sure.  There was no DOD on 2003 5.3 engines.
 
I've had a 2000 5.3 with piston slap issues and my 2002 5.3 used to have bad piston slap on cold start up. Cured both by adding a 1/2 pint of extra oil above the full mark on the dipstick. Started this at about 140000 miles currently at 270000 with no issues. Problem does not immediately stop but you should notice an decrease in noise almost immediately/
 
av-summit said:
Ya it came in 04. ...
NO

Active Fuel Management AKA Displacement On Demand was only available for 2007-2013 for the Avalanche.
 
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