blitz Posted June 16, 2006 Share Posted June 16, 2006 The slap-slap-slapping on my 2.5 had gotten to the point where it was still slightly audible after warmup. After doing the yearly water-blast, carbon-removal thing, I noticed some mitigation of the slapping noise. It's not ALL gone, but it did lessen somewhat. Shades of the GM TSB for top-cleaner routine. **** ******! Link to comment Share on other sites More sharing options...
Dr. RX Posted June 16, 2006 Share Posted June 16, 2006 Not really sure why that would help, the slapping is cause beause the skirts on the piston are not long enough. This causes the piston to wabble slightly in the cylinder, that causes the slapping noise you hear. Link to comment Share on other sites More sharing options...
blitz Posted June 16, 2006 Author Share Posted June 16, 2006 Aggravated by carbon buildup in the squish band. Oh wait... Subaru engines aren't known for that. "There've been a lot of complaints about cold-start knock in the Vortec engine family, and most General Motor's customers are getting incomplete answers at dealerships. We've spoken with Matt Kester, assistant manager with GM Powertrain Product Communications, about the situation. He said General Motor's engineers are aware of the problem and are currently in a research stage. The cold-start knock involves the 4.8L, 5.3L, and 6.0L V-8s in all applicable GM cars and trucks from '99 to '02. They believe the cause is carbon buildup on the circumference of the piston above the top piston ring. This interference is affecting the dynamics of piston travel and therefore causing a knock. It seems the problem begins after the first 12,000 to 15,000 miles, and the knock will last between five and 30 seconds in temperatures below 50* after a cold startup. The noise also seems more pronounced after long trips and at lower temperatures. The use of a top engine cleaner will give only temporary results, if any, and a replacement engine without modifications would most likely develop similar symptoms. We were also told that a Technical Service Bulletin is in the process of publication, which should provide an explanation of the condition but not a fix, and that carbon deposits and associated knock are not causing any structural damage to the engine." Disclaimer: Keep in mind that this "solvent fix" originated from the same company (GM) that determined chronic leaking head gaskets are caused by lack of GM coolant conditioner, rather than design error. **** ******! Link to comment Share on other sites More sharing options...
nipper Posted June 16, 2006 Share Posted June 16, 2006 Aggravated by carbon buildup in the squish band. Oh wait... Subaru engines aren't known for that. "There've been a lot of complaints about cold-start knock in the Vortec engine family, and most General Motor's customers are getting incomplete answers at dealerships. We've spoken with Matt Kester, assistant manager with GM Powertrain Product Communications, about the situation. He said General Motor's engineers are aware of the problem and are currently in a research stage. The cold-start knock involves the 4.8L, 5.3L, and 6.0L V-8s in all applicable GM cars and trucks from '99 to '02. They believe the cause is carbon buildup on the circumference of the piston above the top piston ring. This interference is affecting the dynamics of piston travel and therefore causing a knock. It seems the problem begins after the first 12,000 to 15,000 miles, and the knock will last between five and 30 seconds in temperatures below 50* after a cold startup. The noise also seems more pronounced after long trips and at lower temperatures. The use of a top engine cleaner will give only temporary results, if any, and a replacement engine without modifications would most likely develop similar symptoms. We were also told that a Technical Service Bulletin is in the process of publication, which should provide an explanation of the condition but not a fix, and that carbon deposits and associated knock are not causing any structural damage to the engine." Disclaimer: Keep in mind that this "solvent fix" originated from the same company (GM) that determined chronic leaking head gaskets are caused by lack of GM coolant conditioner, rather than design error. **** ******! GM is also facing a lot of lawsuits on piston slap, so i really wouldnt trust GM on this explination. Carbon buildup after 15,000 miles is prettymuch BS. GM's pisotn slap is rather loud and doesnt always go away. Subarus has been explained and most the time can be lived with (everyone with over 150K on thier enigens and with slap raise your hand). Subaru if you stand your ground will fix it, where as GM seems to be telling its customers to take a hike. the only thing i can think of is that the thread here is that he truly has ping, not slap, then the water method woprks well to get rid of carbon nipper Link to comment Share on other sites More sharing options...
blitz Posted June 16, 2006 Author Share Posted June 16, 2006 GM is also facing a lot of lawsuits on piston slap, so i really wouldnt trust GM on this explination. Carbon buildup after 15,000 miles is prettymuch BS. GM's pisotn slap is rather loud and doesnt always go away. Subarus has been explained and most the time can be lived with (everyone with over 150K on thier enigens and with slap raise your hand). Subaru if you stand your ground will fix it, where as GM seems to be telling its customers to take a hike.the only thing i can think of is that the thread here is that he truly has ping, not slap, then the water method woprks well to get rid of carbon nipper So what you're saying is that he actually has spark-knock that was still slightly audible after warmup? He wasn't really hearing piston slap after all? **** ******! Link to comment Share on other sites More sharing options...
cookie Posted June 16, 2006 Share Posted June 16, 2006 Removing carbon reducing slap is quite possible. The carbon could cause the piston to tilt to one side during firing it seems. Link to comment Share on other sites More sharing options...
nipper Posted June 16, 2006 Share Posted June 16, 2006 Removing carbon reducing slap is quite possible. The carbon could cause the piston to tilt to one side during firing it seems. thats possible on an engine with lots of miles (sorry if i didnt make that clear) but i really dont by that from gm on a 1 year old engine. nipper Link to comment Share on other sites More sharing options...
gbrand Posted June 17, 2006 Share Posted June 17, 2006 I have done the water slap also, but never to address piston slap, in a number of vehicles. if you feel that carbon buildup is a problem, perhaps try RXP? It with a few other things got my legacy under the emissions limits last year. Theory was carbon buildupcaused compression ratio to increase casuing NOX gases to increase while CO and HC were way down, After treatment HC and CO went up andNOX went down, but all were inlimits so I passed... Link to comment Share on other sites More sharing options...
Buick350X Posted June 17, 2006 Share Posted June 17, 2006 Better then the Furd V8 problems. know a guy who put A safe shot of NOS on his new rustang, block crack in half from vally pan on down. Its a known flaw that they have yet to address. Though some companies sell kits to help beef up the vally area where the cracks start. Link to comment Share on other sites More sharing options...
blitz Posted June 17, 2006 Author Share Posted June 17, 2006 FWIW, I didn't blast the carbon with the intent of getting rid of slap, I did it to keep spark-knock in check as a part of my yearly prevantative maintanence. The reduction in slap was incidental. I passed my findings along for two reasons: 1. USMB appears to exist for such a purpose. 2. I enjoy watching people struggle with new and unfamiliar knowledge. **** ******! Link to comment Share on other sites More sharing options...
nipper Posted June 17, 2006 Share Posted June 17, 2006 FWIW, I didn't blast the carbon with the intent of getting rid of slap, I did it to keep spark-knock in check as a part of my yearly prevantative maintanence. The reduction in slap was incidental. I passed my findings along for two reasons: 1. USMB appears to exist for such a purpose. 2. I enjoy watching people struggle with new and unfamiliar knowledge. **** ******! your a bad person, BAD! out of curiosity, did you smoke out the neighboorhood? nipper Link to comment Share on other sites More sharing options...
blitz Posted June 18, 2006 Author Share Posted June 18, 2006 your a bad person, BAD!out of curiosity, did you smoke out the neighboorhood? nipper No man, that's the beauty of using water ...no toxic chemicals. Other than a little steam from the tailpipe, you get a bit of sulfur odor from the cat - sorta like Yellowstone, only not as bad. For all I know it may actually be extending the cat life as well by stripping and releasing potential surface contaminants (sulfur, lead, phosphorous, silicone, etc.) from the cat media. Maybe there is a little bit of toxic fallout from the tailpipe, I dunno. **** ******! Link to comment Share on other sites More sharing options...
nipper Posted June 18, 2006 Share Posted June 18, 2006 No man, that's the beauty of using water ...no toxic chemicals. Other than a little steam from the tailpipe, you get a bit of sulfur odor from the cat - sorta like Yellowstone, only not as bad. For all I know it may actually be extending the cat life as well by stripping and releasing potential surface contaminants (sulfur, lead, phosphorous, silicone, etc.) from the cat media. Maybe there is a little bit of toxic fallout from the tailpipe, I dunno. **** ******! Just the last time i did it on a non cat car i smoked out the neighborhood nipper Link to comment Share on other sites More sharing options...
Olnick Posted June 18, 2006 Share Posted June 18, 2006 After doing the yearly water-blast, carbon-removal thing /quote] What is your procedure for the water-blast thingy, blitz? I've heard of it before but have no idea how one would do it. Mahalo. Link to comment Share on other sites More sharing options...
blitz Posted June 18, 2006 Author Share Posted June 18, 2006 What is your procedure for the water-blast thingy, blitz? I've heard of it before but have no idea how one would do it.In a nutshell: After thoroughly warming up the engine (oil should be at full operating temp), draw water into the intake plenum through a length of vaccum hose, while keeping the RPM's around 3k. Be careful to meter the water carefully so as not to give the engine too large a gulp. Use just enough to cause the revs to drop a bit and give the sound of a slight stumble. Run a good 16-20 oz. through. When you're done, drive the car to vaporize any water out of the oil and exhaust. **** ******! Link to comment Share on other sites More sharing options...
Andyjo Posted June 18, 2006 Share Posted June 18, 2006 so this pretty much does the same thing as the seafoam trick... except cheaper? Link to comment Share on other sites More sharing options...
blitz Posted June 18, 2006 Author Share Posted June 18, 2006 so this pretty much does the same thing as the seafoam trick... except cheaper?I think there's a bit O' difference. The water is instantaneously thermal-shocking and steam-blasting away the carbon, whereas I'd think the Seafoam being a solvent and all, would benefit from some soak-time. I was under the impression that Seafoam instructions were to essentially "fog" the combustion chambers heavily, then shut it off for a period to let the solvent dissolve the deposits, then restart. **** ******! Link to comment Share on other sites More sharing options...
unobtainium Posted June 18, 2006 Share Posted June 18, 2006 It works a little more subtly than steam cleaning: http://jchemed.chem.wisc.edu/JCEsoft/CCA/CCA1/R1MAIN/CD1R1830.HTM Entire towns used to depend on "gasworks" in the UK where they would make water gas out of coal and steam. The snag is the CO is poisonous. Link to comment Share on other sites More sharing options...
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