Dark Spots on Cylinder wall

[Thackdaddy]

I opened up a junkyard 400 I bought to inspect it and saw a dark spot on each cylinder wall like the one pictured...all 8 have it. I have never seen this before, thoughts? The spot is smooth to the touch, if you felt it with your eyes closed you would not feel a thing.

 

[Photon440]

A possible hot spot from a dirty water jacket?

 

[Thackdaddy]

A possible hot spot from a dirty water jacket?

All eight cylinders have the same spot in the same location.

 

[Fran Blacker]

Have you looked in water jackets and pictures. It is odd.

 

[MoparLeo]

Good thing you didn't buy it...

 

[Don Frelier]

Good thing you didn't buy it...

He did say he bought it.

 

[MoparLeo]

Too late then...Best to ask questions before the purchase otherwise you are just hoping for validation.

 

[gdrill]

That is very odd.
Could it be possible that this is a uniquely bad casting and the cylinder wall is actually connected to the exterior of the block. Therefore extreme heat build up with lack of cooling circulation.

I know, pretty far out but hey, that’s a pretty wacky situation there!

 

[khryslerkid]

If that's at each water jacket passage would running an engine with no coolant cause the blueing?

 

[Photon440]

Possibly, but it should be hotter higher up in the cylinder.

 

[Don Frelier]

Coal miners car?
Black lung perhaps

 

[F4R/T]

Crazy I’ve never seen anything like that.. lots of cleaning up and sleaving?

 

[dvw]

Is every spot right above the pistons on the outer wall? Did you take a little carb cleaner to them. Looks like stuff that washed off the top of the piston.
Doug

 

[khryslerkid]

Running Nitro?

 

[threewood]

So the dark spot it just above the piston in every hole? So a piston close to the top has a spot near the top and one down in the hole has the spot lower? If so, it looks like whatever is caked on top of the piston has oozed off, puddled and evaporated. Liquid on the piston would drain to that spot.

 

[khryslerkid]

@Thackdaddy is the head gasket still on the block in your picture? Looks like a sleeve in each cylinder?

 

[threewood]

Get some carb cleaner and hit that spot

 

[Fran Blacker]

Knock out those freeze plugs and have a look! Pictures too!

 

[Thackdaddy]

@Thackdaddy is the head gasket still on the block in your picture? Looks like a sleeve in each cylinder?

Yes, that is the head gasket

 

[Thackdaddy]

If I was gonna guess I think it is from fuel wash. The piston and everything else indicate that was running very rich, unburnt fuel pools washing away the oil film.