Take a look at this piston I pulled out

[jmgtp]

I pulled the pistons out of my old 3.4.

I noticed some marks on the sides. They look like light scratches that run in the direction that the piston travels in the cylinder.

All the pistons have the marks, some look like a bit more than others and some more on one side than the other. If the piston was square, the marks are NOT on the sides where the pin for the small end of the rod is pressed in. I can just barely feel them if i run my fingernails around the piston. The bores in the block actually look excellent, no visible scratches and I can still see the crosshatch pattern.

Are the marks on the piston normal or not? The motor had 120k miles and I used to run it pretty hard. I have someone that is interested in the pistons for a high compression 3400 build but I don't want to sell bad parts. The below pic

[Superdave]

pretty normal for a high mileage 60v6, the Gen 3's have a coating there to help with piston slap but it's pretty much worn off by 50K.

[HOYS]

Would you look at this piston?...lol

As said above, that seems pretty dang normal for that mileage.

[jmgtp]

Ok, given that it is normal, would these pistons be good candidates for a swap into a high compression 3400 build? Should these marks be considered detrimental or undesriable for a rebuild? I don't want to end up with an unhappy buyer.

Just as a side note, the 60v6 bottom end must be pretty stout. This motor has been run hard, had over 120k miles, and all the rod bearings looked perfect. The mains all looked good as well. The front most main bearing did have a single light score in it but the crank is unscathed.

[pocket-rocket]

I would point the buyer to this thread and let them judge. I wouldn't consider it detrimental, but it's not ideal, but as said already, it's normal. Undesirable? You can't be too picky when it comes to parts with 120k miles of hard driving on them. I certainly wouldn't be shocked pulling those out of my engine, nor would I be disappointed, and it's had Mobil 1 every oil change (except 1, when I was flat broke) since 30k.

[Schurkey]

Are the marks on the piston normal or not? The motor had 120k miles and I used to run it pretty hard. I have someone that is interested in the pistons for a high compression 3400 build but I don't want to sell bad parts. The below pic

[ATTACH=CONFIG]5645[/ATTACH]

What you're seeing is both completely normal AND a sign that the pistons are ruined.

Since there is now no way to take an accurate measurement of the piston diameter, there is also no way to determine piston-to-bore clearance.

Scrap metal.

[jmgtp]

Alright, well I think I probably won’t sell them. I don’t want to sell potentially bad parts, its just bad business.

That said, I’m not scrapping them! I need to figure out some kind of cool something or other I can make them into.

I have a welder and I like making stuff. For example, I made this little warrior guy almost entirely out of Corvette and Grand Prix parts. He consists of a few brackets, U joint parts, an exhaust valve and some other stuff. He is free standing and his post is on a window ledge in my staircase.


I have my eyes on the dohc cams to make into lamps. I believe the core of the cams is hollow which will make running the wire easy. And I’ll likely use old brake rotors as the base.

What to do with the pistons/rods/crank….?

[robertisaar]

back in the day, my dad used to make ashtrays out of diesel pistons.

[TechRod]

He's too cool jmgtp, love the little warrior guy.

[jmgtp]

Haha thanks. He was pretty easy and fun to make and most people that see it think its something I bought.

I'd love to do something with the rotating assembly though. Can't decide if I'd want to keep it assembled and tack the rods to the crank so it looks like a rotating assembly outside the block or dimantle everything and use for something else.

[mrl390]

Make a coffee table or end table out of the rotating assembly. Stand the crank upright and with the pistons still attached to the rods, weld the bottom of the rods evenly around the perimeter of the end of the crank. Put a piece of felt on the top of each piston and use them to support a piece of round glass. Should make a cool table.

[pocket-rocket]

That guy is awesome! If you sold them I would buy one for sure, lol.

[road warrior]

The pistons i pulled out of the engine in my 1992 lumina euro 3.4 i rebuilt in 2009 looked just like yours.
Scrap them and put new ones in don't chance it i am glad i put new ones in mine.

[Smittro]

What do your bores look like? That does'nt look normal to me.. @ the same time I also agree they are junk.. I just resently picked up another LQ1 (I have a few lol) with 130k+ on it from a running 92 z34.. Pulled the heads and found the bores still had a ton of cross hatch left, I mean like most of it was still there.. The bores are still within factory spec also. There are no signs of the piston wearing against the cylinders either.. Pics upon request..

Could have been a problem in the ring packs or gap orientation..
Wrong oil type/weight, or crapy oil brand such as Royal Purple garbage.. Could also have been caused by some sort of additives as well..

IMHO.