Guesses? Severe piston slap = high wear metals?

OVERKILL

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Your example has the same small skirt extensions as the 302HO piston, notice that? Whilst that is absent from the LS1 and 4.6L Ford examples. I think that's part of the skirt shortening as they chase friction reduction. What engine is that piston out of BTW?
 
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My wife's '99 Outback suffered from Subaru Genuine Piston Slap and no oil brand nor viscosity helped. It really sounded like an old diesel. I tried everything from green GC to Valvoline conventional 10W40. I only did a couple of random uoa's and uoa wear metals were normal. When I spoke to my dealer's lead tech about it, he told me the only "fix" was to replace the pistons with larger ones which he did on his sister's Outback. I believe Subaru actually came out with larger pistons for that specific generation engine. We decided against a "fix" since we don't have relatives that are automotive techs. smile
 
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Originally Posted By: OVERKILL
Your example has the same small skirt extensions as the 302HO piston, notice that? Whilst that is absent from the LS1 and 4.6L Ford examples. I think that's part of the skirt shortening as they chase friction reduction. What engine is that piston out of BTW?
Mazda 2.5L KL V6 also found in Ford Probe and Telstar. It actually looks like the LS and Modular pistons have at least a bit of a skirt extension beyond the counterweight cutaways, wider along the perimeter than the KLs
 

OVERKILL

$100 Site Donor 2021
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Originally Posted By: PeterPolyol
It's a small piston, 84.5mm (3.32") bore
I'm sure that helps. The Modular isn't huge either at 90.2mm (3.552").
 
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Originally Posted By: mjk
Since it really owes you nothing, and the 5.3 will outlast the body, throw in a quart of Lucas and see if that quiets it. coffee coffee
Why would that work?
 
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Originally Posted By: fredly
You live in PA and don't know about a plug in block heater? That pretty mysterious.
I live in NH and have never seen a parking spot with a place to plug in a block heater, although EV plugs have been showing up. My wife used to live up near Lake Superior and many apartment complexes would advertise that they had place to plug in, but she got a place with a garage instead. Did you wake up with an upset stomach or something today?
 
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Gasbuggy

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Originally Posted By: A_Harman
My 2002 LS1 Camaro has had piston slap since I bought it new. I was pretty disgusted with it, and thought "OK, I've got a 36,000 miles warranty, I'm gonna drive it like I stole it, then bring it back for a new engine at 35,000." I thrashed it mercilessly at autocrosses and track days for 2 years, and the cold start slap never did get worse. So I didn't worry about going through the warranty without replacing the engine. Now at 263,000 miles, it still behaves as it did when it was new. Once it warms up, the engine doesn't have any mechanical noises. But it burns oil now, and I have retired it from track days after accumulating ~200 hours of track time in 15 years. The oil consumption didn't become unacceptable until it had over 240k on it. One thing I found that helped the cold start piston slap was to rev the engine to 1700 rpm instead of letting it idle. The slap noise would go away. Then once the engine got to operating temperature, it ran silently at idle. I ran a lot of different oils in it, but none of them had any effect on the piston slap.
That is awesome. Glad it's still on the road.
 

Gasbuggy

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Originally Posted By: fredly
You live in PA and don't know about a plug in block heater? That pretty mysterious.
I'm familiar, and plan to do it at some point. Though I'm in the least coldest part of PA.
 
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