5.3 carbon knock
Posted 02 April 2002 - 01:00 AM
I have heard that replacing the pistions is the only permanent fix. I have also heard that replacing the pistons doesn't even fix it. Is the best option just using some top engine cleaner every so often?
Any new info on this topic would be appreciated!
Posted 02 April 2002 - 05:31 AM
My observation has been that the guys that run these motors hard (alot of towing and hauling) seem to have less problem with the "start-up knock". I wonder if it's just a coincidence, or if that means something... ???
2005 BMW 645Ci convertible w/only 19k miles
2013 Ford C-Max SEL Hybrid (hers)
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Posted 02 April 2002 - 10:39 AM
BTW, welcome to the forum and site! Here's my 2 cents on this, and what I remember from various discussions.
Seems to be 2 varieties: 1) classic cold-start piston knock;
2) various intermittent "tickings" or "tappings". Some have one, but not the other, some have both. Listened to father-in-law's '00 6.0L this past weekend, and his cold start knock definitely sounds like it's coming from lower down in the engine, than, say lifter noise or upper engine carbon build-up noises.
My '99 5.3L has intermittent very mild "ticking", and seems more prevalent after a lot of stop and start driving and short trips. Like Shaners said in previous post, if the engine is driven a little harder, seems to quiet down the ticking. I also noticed that after using Techron, the ticking has stopped. These would lead me to believe that the "ticking/tapping" may be carbon build-up, rather than piston slap. I'd like to get father-in-law to stand on the 6.0L sometime on a fairly regular basis to see if this helps - honestly, if it is piston slap, then I doubt hard driving would make any significant difference.
GM has been besieged w/ ticking and slap problems, mostly from 5.3 and 6.0 L engines, but my understanding is that deep-skirt block designs are more prone to this, maybe as it's harder to get a perfect alignment w/ piston and block skirt?
In the news section here on this site, there is discussion of a new all-aluminum 5.3L that will be used in the new SSR and also the "stretched" versions of the Envoy and Trailblazer. The press releases go into some detail about polymer-coated pistons, so perhaps we will see this cascade to all LS1 engines in the future - here's to hoping.
Despite what all the hollering sounds like, I think the piston slap issue is confined to a small percentage of LS1 engines. If and when GM decides it's caused enough publicity, they will likely fix the issue. Just hope this includes all older LS1 engines w/ slapping noises. If you check out other topics, there are some threads related to piston slap and various noises as well.
Hope this helps.
00 Olds Alero
91 Chevy Lumina
Posted 10 April 2002 - 01:13 PM
i wonder if its the new $1.30 a gallon gas or maybe GM sent a team to my house saturday night when i was sleeping & they secretly performed some work on my truck... :ehh:
in any case i have not heard it... I even had my wife start the truck the am & i stood next to the frt passenger side & nada.. would be nice if it stays away
Truck just turned 32000 sat night before i parked it.. but from about 18-32K the knock was there....
Strange very strange
Posted 10 April 2002 - 01:45 PM
Posted 12 April 2002 - 09:29 AM
Posted 24 April 2002 - 03:24 PM
On a cold start, it will tick for about a minute. If you give it the gas hard, it will stop ticking while the engine accelerates, but on the decelleration (no throttle) it still ticks. If it were a bleeding lifter, wouldn't it stop when I revved it (due to the increased oil pressure) and stay stopped? If it were a bad piston (such as piston slap), wouldn't it keep on knocking? Once it stops, it doesn't come back until the truck has sat for about four hours or so. My old Lumina had a constant "tick" but it wasn't nearly this noticable.
This whole thing has me seriously considering an extended warranty! Anyone know about how much they are for about 100,000 miles?
It it does "blow up" it will be the last chevrolet I ever buy. I know ford isn't much good either so I guess I'll have to get a Dodge (scary thought - don't like them either). A friend of mine has a Toyota that does something similar. He had a problem with the dealer at first, and I don't know how it came out.
Another question - could this be a normal noise in most cars but more audible due to the plastic intake manifold (yes, they are plastic now)?
Posted 28 April 2002 - 08:40 PM
2008 Chevy Silverado Z71 4x4 Crew Cab 6.0L 3.73 Blue Granite
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