Ok here is what I have come up with for problems on this vehicle.
1. There has been problems with severe amount of carbon accumulating on
piston domes, then causing a cold start knock, the fix for it would be to
remove the plugs add some top engine cleaner in the plug holes and let it
sit overnight, crank engine a few times in the morning to expel any debris
and reinstall plugs. Should be good for 20K or so miles. GM is working on
Teflon coated pistons for a fix for this problem that should be available
soon.
This is the most common symptom and noise that you are describing with a fix
for Cold Start knock. There is also another common problem of a bad oil pump
o-ring that caused a lifter type noise and may be also confused with a
collapsed lifter but bad oring on oil pump causing oil aeration.
Hope this helps, remove plugs and take a peak in the cylinder for high
amounts of carbon on the tops.
Let me know how you make out.
Jonathan Amo
----- Original Message -----
From: "Jon Wennerberg" <jonw@up.net>
To: "Smith, Bill" <Bill.Smith@sandycorp.com>
Cc: "John Beckett" <saltracer@servusa.com>; <land-speed@autox.team.net>
Sent: Saturday, December 27, 2003 9:52 AM
Subject: Re: Piston Slap ? Non LSR
> I've got Mobil 1 5W30 in the truck now -- I'll pay attention for a few
> days and see if the noise is still there.
>
> Jon
>
>
> On Saturday, December 27, 2003, at 11:21 AM, Smith, Bill wrote:
>
> > The 5.3 in trucks has an iron block---5.3 in Trailblazers, Envoys, and
> > others is Alloy----the problem is mostly piston slap as I understand
> > it---I have never heard of one failing,,,If you force GM to change it
> > most likely will still be there and you will have agreed that nothing
> > else will be done---I have heard of people being able to get and
> > extended warranty out of it---my recomendation if it just drives you
> > crazy----I have never heard of being able to stop it
> > completely---Mobil 1 will help some I have been told.---wmts
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