Piston Slap Solution

Discussion in 'GM Powertrain' started by japsmash2001, Oct 9, 2009.

  1. japsmash2001

    japsmash2001 Member

    What is interesting is that carbon cleaner has been noted to help with piston slap.

    If that is true, then the piston rings on one or more pistons must be stuck in the ring land, not allowing the rings to properly support the piston in a cold running state. Most pistons are cam ground, meaning they are egg shaped when cold, and when heated swell to a round shape. The carbon theory may hold creditability. This might explain why owners of piston slapping GM products have higher oil consumption. The stuck rings are allowing excess oil to enter the cylinder chamber.

    Carbon is very hard and difficult to remove. Diamonds are formed from carbon. The cleaner must be one of the harshest chemicals in the automotive world. As the carbon cleaner activates, bits of carbon may be trapped between the top ring and the scraper ring or elsewhere, scoring the cylinder wall. Thus, one has traded one problem for another more serious problem. Therefore, I would not recommend the carbon cleaner.

    My solution is to use a 5W 20W motor oil and drive it hard once it is fully warm. The high RPM and Piston loading will eventually free up the rings, to some extent. Change the oil every 1200 miles for the first three oil changes. Viscosity Improvers in modern motor oils begin to lose their effectiveness after 1200 miles. The GM engine needs the full 20W characteristic in operation to provide proper protection. A long drive will allow the detergents in the oil a chance to dissolve some of the carbon and or sludge, which are sticking the piston rings.

    Piston slap is not all bad. Frictional losses are greatly reduced because the engine has reduced piston skirt drag. I would prefer that GM built my Suburban with out the piston slap, but this particular issue is not as bad as it seems.

    The aforementioned process has worked well for me. Sometimes I hear a little slap when she is cold, it could be a lifter, but she runs great and is silent when warm. I run a 5W 30W Castrol and change it every three months with a GM filter. 106K and pulls like a mule to the 100 MPH cutoff.

    2001 K1500 5.3 original mint condition, 106 K, silver with silver cloth interior, console with key, fog lights, 265 Michelins.
  2. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    Good advice. Some say that piston slap is not detrimental to the engine and does not affect longevity or performance. I can remember my dad's Chevelle SS had excessive oil consumption and piston slap. He drove the pants off that car and at 50k miles the oil consumption slowed to a quart every 5000 miles instead of every 500 miles. The piston slap never went away. The Chevelle made it to 100k before he traded it in.

    Some GM owners whined loud enough to get special polymer coated pistons installed.
    Of course you could always join the class action lawsuit and make the lawyers rich and you'll get a $500 coupon good toward the purchase of another GM vehicle.:glasses:

    Good site: http://www.pistonslap.com/tsb.htm
  3. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    Yes, that is what I read is the cause of the piston slap 5.3 problem.

    I heard-read actually-that it was decided that the top ring was set too low on the early 5.3's. Apparently it allowed too much "crap" to condense above the top ring,and the gunk eventually was carbonized(I guess).

    The cure-I read-was to raise the top ring on later 5.3s.

    I don't know for sure if what I wrote is correct-I don't even own a 5.3(98 5.7 Suburban). It sounds plausible,so I'm repeating it.


    PS I haven't heard any stories of 5.3's genading themselves, so I suspect it isn't a reliability problem, just a "my engine makes this bad noise" problem.
  4. Silverbullit

    Silverbullit New Member

    This may help

    The noise is because of the type of pistons which have no skirt and are what they call hyperconnectic sp they use them is race engines and they are a low friction piston and they are small in diameter in design and need heat to make them fit the cylinder. Seeing as how every single 3.1,3.4,4.8,5.3,6.0 engine that uses them make the noise There can not be that many cylinders out of round. On race engines inwhich they were designed for noone hears the noise over the loud exhaust but they are a true and proven design and have had no durabilty issues that i have seen.
  5. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts


    But all manufacturers use the very little skirt pistons now.Why are the early 5.3 so likely to produce the noise?? If what you say is so, them ALL engines should have the slap?
    Besides, most of the 5.3's -early and late-don't make the noise,so something else is going on.
    Last edited: Oct 10, 2009
  6. japsmash2001

    japsmash2001 Member

    It is a simple matter of poor quality control. Many pistons we're too small for the cylinder bore for the short skirt piston design. The unintended result was not to bad for consumers, it could have far worse. Take the unsuspecting Cadillac customer.

    Early Cadillac Northstar engines have a fatal design flaw. The all aluminum engine has no timeserts in the block. The 10.1 compression ratio engine has a nasty reputation of popping head bolts; the steel head bolt was torqued into the soft aluminum block! Thus the engine would develop a fatal combustion leak, and Cadillac did not stand behind their product. Par for the course for bankrupt GM.
  7. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    What is a timesert-some sort of steel insert to spread the load over the softer aluminum block? I can't believe they would do something so stupid.It must have been a typical "cheapout" driven by the business types that run these companies.

    Maybe it was one of those short cuts that works if EVERYTHING is perfect and perfectly up to spec-metal hardening etc.
    Nissan had/has a similar problem with their Titans.They modified a Dana read end that "should have been able to take the 370 lbs-ft of their nice V-8. Well, it didn't-some of them signed off at just 10,000 miles or less. It was owner abuse-as Nissan implied. Best guess is that the the metal parts in the diff were made with some sort of powdered metal process.It was fine except they required some sort of post casting hardening that had to be done just perfectly.If it wasn't the parts just failed and smeared like toothpaste.

  8. japsmash2001

    japsmash2001 Member

    yes, it was just that stupid. cadillac is a pile of crap. have you noticed the styling of the new ones? makes one want to barf. the greatest luxury nameplate, the world standard of quality and luxury has crashed in a ball of fire.

    Re: Northjunk.

    another theory is that the engine would last long enough to get it safely out of warranty, then the bolts would pop. another flaw of the northstar was the oil pan leaking. This is a 4500 dollar job because the engine had to be removed to do the job, the pan was assembled in 3 pieces. cadillac is the best salesperson lexus and mercedes ever had!

    this is another example how the greatest car company on earth destroyed itself.
  9. TJbear

    TJbear Rockstar 100 Posts

    I just picked mine up a week ago and it does make some clatter after starting it cold. Starts to recede after it runs for about a minute. it's gone totally once warmed up. These engines are so quiet and smooth otherwise, I just think it makes the noise more noticeable. I switched to a synthetic oil right after I bought it and I'm hoping it quiets it down some with time. Might also run some seafoam through it before I change the plugs and wires soon.

    I had a friend insisting it was rod knock but I don't think the sound would go away with warmed up and thin oil. :lol:
  10. japsmash2001

    japsmash2001 Member

    synthetic oil can loosen sludge which could plug the oil pickup screen, which would destroy the engine. which is why i do not use it.

    it is ok to use from brand new, in fact, i have seen the insides of engine with 100k which look new with synthetic oil use.

    you are right, rod knocks blow quickly, unless it the the old 390 or 360 fords, which can run for years with a rod knock. i

    i would use a 5 30 castrol.

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