502 cylinder problems???

[69ptcamaro]

I have a 502 that I pulled the heads off of today and the number 6 and 8 cylinders have a place in them unlike any I have ever seen. Number 6 has a horizontal, somewhat jagged line in it about 3" long about 1/3 of the way down the cylinder. It looks like a crack. I can feel it with my fingernail. I have never seen a block crack horizontally like that, and I can't figure out what in the world would have made it crack. In number 8, it is the same thing, but about 1/2" down in the cylinder and only about 1/2" long. The block is low mileage. The honing marks are still clearly visible. Anyone ever seen this? Does it sound like cracks to you all? I just can't think of what else they could be considering I can feel them with my fingernail. I definitely don't think it is stain of oil from the engine sitting a long time. It has been sitting for a couple of years. Thanks

[Vegas69]

Do you know the history or the engine? Possible it sucked down some dirt or debris.

[69ptcamaro]

I know the history of it fairly well. I just can't really see it making a horizontal line like that from dirt or a piece of metal. It looks like that would make a mark vertically in the cylinder.

[Ranaexcavating]

If it sat for a length of time witout being started it could be rust from a piston ring. How was the engine stored?

[69ptcamaro]

It has set for a couple of years, but it was oiled well before being stored. Plus, I wiped the cylinder down as good as I could. I don't think a rust stain would catch your fingernail either. The other thing that leads me to believe it isn't a stain is that you can't line the pistons up with the marks. For example, if you match the number 8 piston to the mark in the cylinder, the number 6 piston is all the way down in its stroke, but the number 6 mark in the cylinder wall is at the top. They about have to be cracks. I don't know what else it could be.

[Ranaexcavating]

Did you run the engine before you disassembled it? I would think it would have pressurized the coolant system, or had major blow-by.

[69ptcamaro]

No, I didn't. I wish I could have.

[Vegas69]

Oh...I thought you meant the line was up and down. Ring rust is my guess as well.

[69ptcamaro]

I will post a pic later today. I don't think it is a rust ring. I wish it was.

[69ptcamaro]

[img=http://img229.imageshack.us/img229/3961/005kp7.th.jpg]

I hope this helps.

[ZZ430]

I had the exact same thing on one I did a couple of years ago.

It needed an oil truck to follow it around. It would use a quart of oil in a couple of hundred miles.

I ended up doing a complete overhaul on it, using proper hone procedures this time!

Mine was so bad it looked like a tool broke or something. 4 cylinders were like that!

Mine sat on a stand for a year before it was installed (out of warranty) All the phone calls to the dealer, the district rep etc were futile. Even though it had less than 3k miles on it, it was out of warranty because of the 12/12 thing.

Of course they use a "low tension" oil ring, and the lands are not cut deep enough in the pistons to use any other rings but theirs. No aftermarket source had them....so, I had to buy a set of rings each 8 packages at $50 a pop. I considered changing to aftermarket pistons that I could use standard rings, but I didn't want to rebalance and all. $400 for rings upset me, but it was cheaper than pistons and a rebalance.

[pdq67]

Sounds like a whole buncha GM's "Better Idea's" here!!

pdq67

[TonyHuntimer]

The picture is too blurry to really tell what it may be.

Tony Huntimer
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