Piston wash

[Donald]

I was watching a short YT of Dave's Auto and he shows a V8 engine without heads. Points to one piston where the outside edge of the top surface of the piston looked cleaned. He explained that worn rings in that cylinder had allowed oil to get by l and clean the outer edge of the top surface of one piston.

Assuming he is right I learned something.

Unless something really odd happened I might guess if one piston was showing piston wash they all would to some extent.

 

[michaelluscher]

My experience with pistons in a running engine with oil consumption is the exact opposite

These might be different scenarios

 

[Kira]

It's not unheard of for oil delivery to vary among the cylinders.
Perhaps the cylinder you saw was at the end of an oil gallery and thus, starved occasionally.

 

[supton]

Thought I saw a bit like that too, but was confused by it. Oil would leave deposits. Coolant tends to clean. And I'd expect gasoline to possibly wash down too, if heavy enough--not running rich, but like flooded out repeatedly.

 

[bullwinkle]

Usually clean piston=coolant leak steam cleaning… Excessive oil burning=greasy black sludge…

 

[Donald]

I don't have any experience in this area since I only rebuilt a 289 in my 1965 Mustang.

But the guy (Dave I assume) at Dave's Auto seems like a guy who knows his stuff in a shop with fancy & expensive engine machinery.

Watch one his videos and see what you think.

 

[Vitamin Yoda]

I saw the video as well. I think most of his videos are meant for advertising his business, and most of his YouTube shorts are meant to advertise his long-form videos.

Not everything he says is 100% right. Like all people, he's fallible. As to piston wash, I'm inclined to believe what others have said here: it's from coolant. Oil doesn't burn in that pattern inside a cylinder, on top of a piston, and it also doesn't leave a clean a partially clean piston.

One of the shorts that stood out to me was about using not believing the AMSOIL long drain interval myth, and that magnets don't work on oil filters. It seemed about as click-baity as it gets.

 

[daves87rs]

His Videos seem pretty good…

 

[Donald]

I saw the video as well. I think most of his videos are meant for advertising his business, and most of his YouTube shorts are meant to advertise his long-form videos.

Not everything he says is 100% right. Like all people, he's fallible. As to piston wash, I'm inclined to believe what others have said here: it's from coolant. Oil doesn't burn in that pattern inside a cylinder, on top of a piston, and it also doesn't leave a clean a partially clean piston.

One of the shorts that stood out to me was about using not believing the AMSOIL long drain interval myth, and that magnets don't work on oil filters. It seemed about as click-baity as it gets.

Well you don't own that big of a machine shop for 30 years (I think that is what he said) without learning a thing or two.

But it does not mean he knows everything.

 

[Vitamin Yoda]

Well you don't own that big of a machine shop for 30 years (I think that is what he said) without learning a thing or two.

But it does not mean he knows everything.

I think he knows a lot. When you're involvec in repairs, you learn very fast. I also think that there is a difference between what he knows, and what he shares. YouTube has a tendency to corrupt people into making click-baity content. YouTube shorts don't pay anything, so everyone makes them to funnel the audience to their content. Once creators get a taste of that sweet YouTube money, they don't really want to go back to doing whatever it was that made them money in the first place.

 

[dfarr67]

Fuel wash or coolant leak.

 

[DGXR]

I believe that episode showed that the cleaned piston also had a broken ring land below the oil control ring, which allowed the excess oil to enter that one cylinder. In this case it would not happen to all pistons & cylinders.

 

[Faawrenchbndr]

I believe that episode showed that the cleaned piston also had a broken ring land below the oil control ring, which allowed the excess oil to enter that one cylinder. In this case it would not happen to all pistons & cylinders.

It’s all about the fine details……

As for the videos, I take all YT videos as entertainment, there is often an educational value as well.