G-Man said it all. I tried different oils and found Castrol Syntec did get rid of most of my knock on my 3.4 engine in my wife's Aztec. Have not tried Start up or Blend.
Chevy Piston Slap
- Thread starter Red Dog
- Start date
- Status
My Subaru's engine has even less skirt than the Chevy or Hondas pictured above, and yes it sounds like a diesel. When the time comes to sell this car, it's getting a load of SAE#30 or #40.
"Around 1998, GM switched from a "Select Build" method of manufacturing and/or assembling engines to a "Net Build" method, in order to save money on manufacturing and/or assembly. In the Select Build process, pistons and cylinders are matched for size and fit. GM's new "Net Build" method of manufacturing and/or assembly, in contrast, assumes all pistons will fit equally well in all cylinders and does not allow for variations in the size of engine cylinders or pistons. The pistons of slightly varying size (all within spec) are not individually matched with the cylinders of slightly varying size (all within spec)."
Wow, talk about a big jump backwards. The service manual for my 1965 Cadillac lists about 10 slight variations in piston size which were measured and marked at the factory. Engine assemblers measured each bore and also made a letter mark. "A" pistons were put into "A" bores, "B" into "B" and so on. Good engine rebuilders achieve the same thing by custom honing each bore to give the correct clearance with the actual piston which is inserted into it.
These are things to think about when you see GM proudly telling the financial press how much money they have "saved" through "productivity" enhancements. An engine with enough clearance to create audible piston slap is clearly wearing it's bores and pistons more rapidly than one where the clearances are correct. Having purchased three new GM products during the past 15 years (none of which we still have) I am now a member of the never again club.
Wow, talk about a big jump backwards. The service manual for my 1965 Cadillac lists about 10 slight variations in piston size which were measured and marked at the factory. Engine assemblers measured each bore and also made a letter mark. "A" pistons were put into "A" bores, "B" into "B" and so on. Good engine rebuilders achieve the same thing by custom honing each bore to give the correct clearance with the actual piston which is inserted into it.
These are things to think about when you see GM proudly telling the financial press how much money they have "saved" through "productivity" enhancements. An engine with enough clearance to create audible piston slap is clearly wearing it's bores and pistons more rapidly than one where the clearances are correct. Having purchased three new GM products during the past 15 years (none of which we still have) I am now a member of the never again club.
wgtoys,
I just want to say thanks man.
You're putting out some high quality posts that I find intriguing and educational.
I just want to say thanks man.
You're putting out some high quality posts that I find intriguing and educational.
Due to the obscene amount of driving I have to do, I tend to buy beater cars. Older vehicles with low miles. My WORST luck has come from GM vehicles. I have had good success with Ford and Dodge but never GM. I'm currently driving the wheels off a 96' Legacy.
I have a 2004 chevy 1500 5.3L. No piston slap at all, ever. 43000 miles now. It is not as common as this forum leads people to believe. In fact, I have heard a lot of chevy's and know people who own them and not once have I ever heard it.
Quote:
Knock knock...who's there?
Grrrrrrrrrrrrrrrrrrr
Do a "Google." Piston slap HAS to be pervasive for so many sites to mention the problem.
I love it!!!! I want one to go in my shop's waiting erea! Now that's the type of GM owner I see almost daily and for some reason they think venting on me will fix p$ss poor build quality. I love it. GM needs to see more customers like this and maybe they will give the consumer their money's worth for a change.
Quote:
wgtoys,
I just want to say thanks man.
You're putting out some high quality posts that I find intriguing and educational.
More like internet rumor/trash talking post from haters and no back up data. GM has won three court cases already. Reason? No data to back up these claims.Folks could not prove they were damaged by being able to hear the pistons slapping the walls of the cylinders. Engine performed and ran perfect. These are of course the exception and not the norm.I have been around and worked on a boatload of LSX's and will tell you face to face I have never seen a "bore damage"...ever....not even anything remotely resembling bore damage and I have heard some real slappers come in.
I can go google some Ford haters and post up their "blurbs"...doesnt make it gospel or even accurate....I take exception to post like these from unknown sources with unknown goals and agenda's. Educational read? I dont think so.
And dont forget Chrysler has the same issue and has also been sued for piston slap. And they won also.....
I would respectfully disagree with the assesment that only a few engines are affected. The degree and intensity of the noise varies but from the GM products that come through my shop as well as two of my friends that own shops,there are alot of them out there that should have customers incensed by GMs lack of pride in the mess they build. Just because a manufacterer wins in court does not mean the customer got what they paid for. Treating customers that way may be why Chrysler is for sale and GM is in the toilet.
With the advent of all-aluminum engines and ever increasing desire to lighten components some cold-rattle is to be expected in some engine designs but the noise I have heard from many GM v-8s is rediculous by any comparable standard. The bottom line is GM isn't going to stand behind their mistakes until the market forces them to and that has allready begun to happen. I laugh at GM's financial woes. I have alot more sympothy for the family that paid hard earned money for one of their products only to get treated like scum by the district manager that represents GM.
I tell them to buy something else that has an excellent track record for reliability and resale. Is the noise normal? Maybe for a GM it is.
I had a 2002 slapper....used pennzoil 10w40.dino....drove it 90,000 miles with no oil useage and 16/21 mpg. Traded it in. The 10w40 works in summer 10w30 in winter but you never get all the cold slap out but the 10w oil takes it down to less than 30 seconds. 3000 OCI's are the answer as a slapper will shear out 10w dino in 3000 to black water.
Family and friends have had over 10 GM V6 and V8s in the last 15 years - never heard any slap and all cars have/had over 100k mostly trouble free miles. I can't complain.
I've heard the GM piston slap in a 5.3 Suburban, my 3.4 Impala and my 2.2 Cavalier. I agree that it's a common problem, but it always goes away (from my experience) when the engine is warm and is very slight or not noticeable when outside temp is warm. Worst case of piston slap I ever heard was a mid-eighties Nissan Hardbody 4 cylinder pickup truck. It sounded just like a diesel but quit after it warmed up. It's not just a GM issue, but seems to be more common in certain GM engines. It doesn't seem to be an issue in how long the engine lasts. Just annoying.
Exactly - that is what I'm reading from every source that isn't connected to that "piston slap" website.
Toyota also has problems with piston slap, but apparently Toyota also says it's normal too(granted they did try to pin sludge on the customer, but I'll give them the benifit of the doubt
http://www.tundrasolutions.com/forums/en...-look-knocking/
http://www.tundrasolutions.com/forums/1gen-tundra/80137-tundra-engine-noise/
CC: I agree that it's certainly not just a GM problem. That said, your comment points squarely toward what I see as perhaps GM's biggest problem: their apparent willingness to tolerate the on-going presence of problems that annoy, irritate, and ultimately alienate people who at one time (purchase) had enough confidence in the product to fork over to GM tens of thousands of a family's hard earned money. Are the additional profits GM banks by no longer doing the A,B,C piston fitting worth the additional ding against GM's credibility and all the alienated customers???
You are right; it is not just a GM problem. When I bought my 1999Ford F-150 with the 5.4 liter engine, it had this piston slap problem. I didn't know what it was back then, but when I had my truck in the dealer's service dept I mentioned the noise, and they, without question, replaced my engine, and it has given no problem since then. This was a well known problem back then, and the dealer apparently had these replacement motors already in stock.
This apparently became too expensive quickly, and I understand they have been telling people that the noise is normal and they have to live with it. It's a real shame that Ford and Chevy have suddenly, after almost 50 years of building V-8s without piston slap, have cheapened their manufacturing process by skipping the selective fit process, thereby sentencing a certain percentage of customers to this knocking syndrome when the tolerances stack up the wrong way.
This apparently became too expensive quickly, and I understand they have been telling people that the noise is normal and they have to live with it. It's a real shame that Ford and Chevy have suddenly, after almost 50 years of building V-8s without piston slap, have cheapened their manufacturing process by skipping the selective fit process, thereby sentencing a certain percentage of customers to this knocking syndrome when the tolerances stack up the wrong way.
My '04 5.3L has had very few issues with piston slap. Mostly noticeable on cold mornings during long OCI's.
The best performing oil for me was GC. Only the slightest bit of piston slap during AM startup which quickly went away. Must be something in Castrol's products based on GMAN's comments.
Currently running PP 10W-30 which seems fine as well. Worst oils were Mobil products. My engine sounded like an old diesel with M1 and DC7500 in it. No more Mobil products for me.
I used to drive an '01 Silverado 2500 with a 6.0L that had seen a hard life as a tow vehicle. That thing would rattle like crazy in the AM but was fine when hot. Motor still pulled nice and strong with a 7000+lb trailer behind it.
The best performing oil for me was GC. Only the slightest bit of piston slap during AM startup which quickly went away. Must be something in Castrol's products based on GMAN's comments.
Currently running PP 10W-30 which seems fine as well. Worst oils were Mobil products. My engine sounded like an old diesel with M1 and DC7500 in it. No more Mobil products for me.
I used to drive an '01 Silverado 2500 with a 6.0L that had seen a hard life as a tow vehicle. That thing would rattle like crazy in the AM but was fine when hot. Motor still pulled nice and strong with a 7000+lb trailer behind it.
I had an 11000 dollar engine built with specs, dyno sheets all the bells and whistles from a high dollar reputeable company. Well after a couple thousand miles I thought I heard a weird noise. To make a long story short, the number one piston was a 20 over vice a 30 over. The company that built the engine couldnt believe it, and refused to fix it. WOW, but the company that made the piston JE, replaced the piston and rings for free. I pulled the engine myslef, but I had to pay for some minor labor at the machine shop.
Piston slap is not the end of the world, and if it set up wrong and you have too much, fix it, otherwise turn up the volume and forget about it! J/K
Piston slap is not the end of the world, and if it set up wrong and you have too much, fix it, otherwise turn up the volume and forget about it! J/K
- Status
Similar threads
