Loud knock noise that goes away after 1 min cold start
11-27-2010, 06:06 PM
#21
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Emissions are removed. I did try a Seafoam about a month ago... put half in the the tank and did other half though brake booster. I only let it sit for 30 min though. It did seem to help.
I read another thread about using the Mopar version, use it though the front PCV tube, and let it sit for like 2 hrs. I want to try that
I read another thread about using the Mopar version, use it though the front PCV tube, and let it sit for like 2 hrs. I want to try that
11-27-2010, 11:11 PM
#22
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I still say it has piston slap! The big give away is the cold temp and then its gone after warm up. Oil change with thicker oil will not change this problem, neither will using any seafoam or techron additive. This is a problem based on the piston bore and piston diameter. I maybe wrong but this is still my guess.
If it is piston slap the problem is not really to be worried about. Just normal LSX platform. If it helps any just listen to a forged piston when cold in an allum block when set up for a big shot of NOS. Can make a hell of alot of noise.
Again just my .02
If it is piston slap the problem is not really to be worried about. Just normal LSX platform. If it helps any just listen to a forged piston when cold in an allum block when set up for a big shot of NOS. Can make a hell of alot of noise.
Again just my .02
11-28-2010, 12:48 AM
#23
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I suggest you dont put chemicals in any component of your car to fix a noise. For there is no jesus juice that contains little techs that go in and fix things. band aids at most.
11-28-2010, 12:54 AM
#24
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and on a side not piston slap can devolpe later on in an engines life. major thrust can egg shape the bore slow or fast. Just depends on how often the engine is really put to work.
11-28-2010, 07:42 AM
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I tthink its piston slap. 148k and some abuse- piston skirts and bores are probably showing some wear. The piston to bore tolerances are too high and causing the knock. When the piston gets hot, the metal expands and it fills the bore. My truck has 178k and sounds like a rod is coming out when its first started. Very loud knock, but it goes away when warmed up. Post a video.
11-28-2010, 07:58 AM
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#01-06-01-028A: Info - Engine Knock on Cold Start - (Mar 18, 2003)
Subject: Engine Knock on Cold Start
Models: 1999-2002 Chevrolet and GMC C/K Pickup and Utility Models
2002 Cadillac Escalade (2WD)
with 4.8L, 5.3L or 6.0L Engine (VINs V, T, Z, U -- RPOs LR4, LM7, L59, LQ4)
--------------------------------------------------------------------------------
This bulletin is being revised to add an additional engine to the models section. Please discard Corporate Bulletin Number 01-06-01-028 (Section 06-Engine).
--------------------------------------------------------------------------------
Some of the above vehicles may exhibit an engine knock noise that begins in the first 19,000-24,000 km (12,000-15,000 mi) of use. The knock noise is most often noticed during initial start-up and typically disappears within the first 5-30 seconds (may last longer in extreme cold temperatures). The noise is usually more noticeable on the initial start-up when the temperature is below 10°C (50°F) and may be more pronounced on the first cold start following a long trip.
This noise may be caused by an interaction between carbon that has formed on the piston, the piston motion and the cylinder wall. GM Powertrain Engineering, and an analysis of engines with this condition, has confirmed that the noise is not detrimental to the performance, reliability or durability of the engine. THIS NOISE DOES NOT HAVE ANY EFFECT ON THE LONGEVITY OF ANY OF THE ENGINE COMPONENTS.
Important: At this time, attempts to repair this condition by replacing the engine assembly or pistons are not recommended.
Please share the information found in this bulletin with customers who inquire about this condition. In the event they have additional questions or concerns, please advise your Area Service Manager.
What are you talking about? PISTON SLAP GOES AWAY.
11-28-2010, 08:10 AM
#31
Thats not even the right bulletin for our cars.......I don't think you know what you are talking about. I've owned these ls1 cars a long time, I think I know what the engine sounds like after 10 years.
Last edited by O2Form; 11-28-2010 at 08:23 AM.
11-28-2010, 09:18 AM
#32
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But it is a tsb on piston slap saying that the condition can and should go away as soon as the car warms up. Were all arguing over something we cant hear. Thats like diagnosing soley on a customer complaint. apparently we dont need to verify things these days
11-28-2010, 09:49 AM
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From the OP's description, it sounds like piston slap. Mechanical problems like rod bearings don't go away, they get worse. There is no way to tell without actually hearing it.
11-28-2010, 01:42 PM
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Just leave it alone. 95% of the time it's piston slap. My car had it at 35k miles when I bought it. I worked midnights and it got pretty cold over here in STL. It is loud. The colder it is, the louder the slap is. Tear it apart, put it back together, and enjoy the piston slap some more!
