Weird marks in cylinder, good compression

[jenkins71]

Hi guys, my other thread is getting long, so i figured I'd ask a question here.

Long story short, I had two blown head gaskets on my 440 (which was rebuilt in the last ~10 years).
Before pulling the heads, all the cylinders showed high compression in the 150-160 psi range after a test, except the cylinders that were affected by the blown head gaskets.

After pulling the heads, I saw that the #5 cylinder, which showed 130psi on the test (DESPITE having a crack in its head gasket--would probably show 155+ had its head gasket been fine) had the weird mark on its cylinder wall:

its not a streak like from scoring, and it is very smooth. If you close your eyes you can barely feel a little roughness on the mark.

other than that, the bores look pretty good. You can see the crosshatch in all the bores and the ridge at the top of the cylinder is so slight, you can't even catch a fingernail on it.

Any ideas what this is or what to do? I hadn't planned on removing the pistons, and my budget for this build is LOW!!!!!!

 

[69Bee]

I think it is just an old water stain. If the motor sat for a while, maybe got water in it from the intake, and then the piston running cleaned the rust, and left this mark.

 

[jenkins71]

Thanks for the reply! If that was the case, what would you do about it?

 

[69Bee]

If it is smooth, and compression is good, I would not worry about it. You state that your budget is low, and you will spend a bit on new pistons & rings, boring & honing, cleaning, etc...

 

[JRL]

You'll probably be fine, but if it was me I would hone it and repace the rings myself.

 

[Rodney]

you didn't mention if the block has been bored over sized?
we had a .060 over late model 440 which wasn't sonic tested for cylinder thickness, after a few passes down the race track
we got water in the oil, after taking a look at the cylinders it had a crack running the direction of your stain.
they were difficult to see since they close up when the engine cools down. they were sneaky little sob's, it took us 2 tare downs to find what was going on.

 

[jenkins71]

It is .030 oversize

 

[Cranky]

What rings do you have? I've taken some 600 wet dry to stuff like that before and never had a problem. The 'stain' didn't come completely off but the majority of it did.

 

[jenkins71]

I'm not sure what rings are in there. I'm thinking I'm going to re-ring and hone just for peace of mind. I already ordered some moly Sealed Power rings. Got a great closeout deal from Rock Auto! $70, shipped, for the whole set!

Cranky, wouldn't sanding possibly put the cylinder out of round?

 

[lewtot184]

i think it's water. might be condensation but could be ant-freeze from the head gasket. anti-freeze is corrosive.