Recommendations for Chevy Piston Slap?

[Lonnie]

I've seen tear-downs of slapping engines and saw different things. If the piston slap is caused by carbon build up at the edges of the piston and near the top of the piston stroke then something that cleans that out can help. If it's mechanical contact between engine parts then nothing will help short of a mechanical fix. Piston slap comes from a lot of cases and until they can be separated you are just guessing, which could make solving the problem more difficult. If say GM says it causes no harm you don't know if that answer is coming from an engineer or a bean counter.
But an interim solution is worth the experiment. Try cleaning out the engine and then a different oil.

 

[mstrjon32]

Believe what you will, but when I sold my car with ONE HUNDRED AND NINETY FIVE THOUSAND miles, it still did 29 mpg on the highway, used a negligible amount of oil (less than 1/8 a quart in 3,000), and had power as good as the day it was new. The oil it did burn, I'm relatively sure was due to worn valve stem seals.

That engine still has another 100K of life left in it; I hardly dragged that car to the scrap yard, in fact, even with the high mileage, rust, and a big dent, I sold it for $2400.

Honestly, I don't see why people get so worked up because an engine makes a slight ticking noise for less than a minute. Granted, some engines do have a severe case which may be perceived as annoying, but I've never found it any more annoying than being in a buzzy 4-cylinder OHC engine (which isn't really annoying at all, anyway). I can see trying a few different oils and filters, I know I did, but beyond that I don't see the need to tear engines apart and create web sites and class action law suits.

 

[BradC]

Quote:

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Why did they not just re-bore the cylinders and fit the first oversize piston and rings, rather than the entire engine? Warranty concerns?

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It was still under factory warranty and was a lease.

I took it in saying it was slapping. They investigated, indicated that it was slapping badly and started the process of the fix, which is usually just replacing the pistons with ones that have teflon on the skirts.

As part of the process, they also measure the cylider walls and that's when they found the larger problem. #2 and #4 cylinder walls were damaged "beyond repair" so they opted to replace the engine on their dime.

But GM Canada does things a lot different than GM US does when it comes to issues like this.

 

[GROUCHO MARX]

"But GM Canada does things a lot different than GM US does when it comes to issues like this."
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Man, it certainly seems so.

 

[Lonnie]

What you are saying that the noise means nothing? I prefer an engine that is quiet. A friend had it written into his contract that if there was any piston slap that they would replace the engine, a Chevy V8 in a light duty pickup truck. It did and they did. I would suggest the same if you're considering buying a vehicle with a knows piston slapper engine. It's better to get the objections out in the open before you start putting any money down. And a closing question. Why did his replacement engine show no signs of piston slapping, same model engine?

 

[honus402]

Delo 15W-40 was the cure for my dad's GMC Denali, but not because of the viscosity. M1 15W-50 made it worse.

 

[ThirdeYe]

I highly doubt it's due to carbon build-up. It doesn't consume any oil and it's always been changed at 3k miles. It does seem to go away after a while but I haven't timed exactly how long. I'll check next time we use it. In my stash in terms of conventionals I have: Havoline DS 5W-30, Quaker State 5W-30, Mobil Clean 5000 5W-30. Planning on trying the Clean 5000 next. If these don't take care of it, I might try some GTX. I check under the oil filler cap every time I change the oil in it and it's nice and shiny clean. I have tried teaching my mom a few more habits that would be less destructive on an engine though, such as telling her to let it warm up for at least 30 seconds before taking off, and taking it slow until it warms up more. Hopefully that'll help a bit, too.

 

[BradC]

Quote:

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And a closing question. Why did his replacement engine show no signs of piston slapping, same model engine?

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Probably because the car was a POS and I didn't keep it long enough after the engine change to see if it would slap again

Chances were pretty good that the new engine had the modified pistons that had teflon on the skirts to suppress the slapping sound. So even if it was slapping, it likely wouldn't have been heard.

 

[ThirdeYe]

I bought her some MaxLife 5W-30 today, hopefully that'll help a little. If not, I'll try a 10W-40. As far as I know, a 10W-30 is actually thinner than 5W-30 at most temperatures at startup, besides freezing anyhow.

 

[ThirdeYe]

Just an update, the MaxLife didn't really solve the slapping problem. Still sounds the same. Thinking of moving up a grade, would a 15w40 be a better choice?

 

[Bobert]

There was a previous thread where someone said Castrol Startup was best at reducing slapping if you can find it (discontinued). He said the next best was Castrol Syntec Blend.

 

[PT1]

Try pennzoil 10w40 in summer 5w30 in winter. The 10w40 will reduce the noise but not solve the problem.

 

[double vanos]

My wife's 5.3 was quieter with GC. The slap was nearly non existant.

Changed to M1 10w30 and it started slapping it's a$$ off right away. I am saving my GC for der Bimmer so maybe I'll try Syntec 5w40 next. I'll get back with how that works out - about 7,500 miles from now (if the engine doesn't blow by then). Cheers.

 

[cfromc]

Some of the 10W-30 oils, as mentioned in a couple of posts, are actually thinner than some 5W-30s at 40C. Some people may think they are putting a thicker oil in because its a 10W-30 instead of a 5W-30, when in fact they may be very close or thinner at normal summer start-up temperatures. I have been looking for something on the thick side and have really been looking at the 40C viscosity. Many of the 10W-30s and 5W-30s have similar 40C and 100C viscosities and just differ at the extreme cold thickness and VI.

 

[Lonnie]

Piston slap is a sign of problems. It may not shorten the life of a given engine but it can be designed out. These manufacturers know how to do it right. It's just not being done. Cheap, cheap, cheap.

 

[cfromc]

Lonnie, I really don't think price is the major consideration. I think it has more to do with MPG and HP; price may just be a very, very tiny side "benefit" to the manufacturer.

 

[mikeg5]

what does a piston slap sound like?? i know my tacoma has a slight ticking noise but i think its the nature of the beast (valves ticking)

 

[ThirdeYe]

In my mom's car it sounds like someone's repeatedly knocking their knuckles against a wood table.

 

[cfromc]

Its a tick or a knock that varies in frequency with RPM. In bad cases and/or in extreme cold it can make the engine sound like a diesel.