This was the area I was talking about. They were all packed full of crud. In the one between cylinder 1 and 2 the deposits were so hard they put a large indentation in the head gasket. I assume these are coolant passages?

After I get the head back on I'm going to do a coolant flush with shout soap, then a citrus flush. Get a lot of the crud out of the block.

Fix that before the head goes back on.

Have you checked to see if all your holes in the new style gasket and the head match up?
I think they made some new holes... for cooling purposes..... later on... which might need drilling to bring up to ' newer style '....and improved performance...

The slots are "steam holes". An engine with siamesed cylinder bores needs these to allow coolant to circulate in the dead area.

This won't cause oil to enter the coolant. You really need to find the actual source of the oil. Given the car had an external head gasket coolant leak, is there any chance what looks like oil is really coolant sealer?

Well the coolant was black, and I thought exactly that. So before all this started I flushed the engine really well with water. Then I drove it around for an hour. When I removed the radiator cap I had dime sized droplets of oil floating by in the radiator.

I'm really at a loss as to where on the head it was leaking. I do remember when I pulled the head the coolant passages on the right side of the engine had a lot of oil near them on the gasket. Although oil was everywhere when I unbolted it.

And I dug out the steam holes and their little passages in the block. Nice and clean. I'll check the head gasket for matching holes when I get home.

Do you have any way to ' vat ' the head ?

Why do you call them ' steam holes' ? Does anyone else call them that ?
Do you really think that in the cooling system there exists pockets of ' steam' ?

Would that not indicate an improper hot spot ? In the same way that not having air in the brake lines.... a place where liquid flow is stopped due to the compressibility of the steam pocket ...
which is a situation where much less pressure is being applied for flow by the water pump than the master cylinder applies to the liquid stream in the brake system.
Isn't using the words ' steam holes' misleading with regards to the physics of the situation ?

No. You can't vat an assembled head right? The machine shop milled it, put in new valve guides, new valve seals, pressure tested it, and did a valve job. When I took it off the car I used 2 cans of de-greaser on it and flushed out all the passages as well as I could. I think it's reasonably clean. Certainly could be cleaner.

No, has to be completely disassembled ..... you could rig up something so you could inject fluid into each of the holes to make sure none have a hidden blockage....which is something which could have caused the uneven heating or cooling which caused the warping which you measured....

Type into your Google machine " Steam Holes " , " Steam Holes Chevy 400 " , " Steam holes Ford 289 " and post the results of what you have found.
Yes, this is one of the reasons a pressure cap is used and the thermostat has a smaller orifice than the hose / piping / cavity leading to and from the stat.

The pressure cap raises pressure to raise coolant boiling temperature. The thermostat restriction raises _block_ pressure even higher to further raise boiling temperature. Just because the gauge isn't pegged doesn't mean that coolant somewhere in the engine isn't boiling.
Yes, and in addition to the above, steam holes are drilled to promote coolant flow into dead areas. Hot spots are caused by an area that has poor coolant flow resulting in localized boiling. The bubbles don't have to make their way to the radiator cap or cause the temp gauge to rise. Coolant temp is an average of engine metal temp. If one keeps coolant flowing to all areas, a hot spot isn't generated.

Some heads are known for cracking in certain sport, this is usually caused by localized boiling. Put a pan of water on a stove and start heating it. early on there will be bubbles that don't make their way to the surface, this is called nucleate boiling.

Again to the Google machine Type in " nucleate boiling cylinder head " and " nucleate boiling engine cooling "

I see there has been some research into making use of nucleate boiling for increased cooling capacity but I'd think that it would be too difficult to control / predict in the real world. http://cdn.intechopen.com/pdfs/13356.pdf



The brake line situation is different. Air in a brake line is like adding an extension spring in series to a parking brake cable. Yes, the cable will pull but it might take more travel than the system has. Air in a brake line won't stop fluid flow since fluid is being pumped through the line.
No, though calling them "Anti steam " or " Steam relief " might be more technically more accurate.

I am saving this space ... I just lost a long post due to ' database error ' by the site... bummer

From the PDF link I posted, near the bottom of page 1:

The above is a really complicated way of saying the bubbles from localized boiling don't make their way to the top of the system and the engine has no apparent signs of overheating.

Also, while not stated in the quote, this localized boiling is cavitation and can lead to metal erosion.

Another complicated way of stating that the engine is overheating and pushing steam out of the rad pressure cap.

Is that pdf describing a diesel engine ?
The two examples you gave were gasoline engines...
With 50-50 antifreeze mixed in... with a radiator cap doubling the pressure... and the cooler running diesel engine fuel... I am having a hard time visualizing steam no matter how thin a layer... ?

Diesel engines run cooler when _lightly loaded_ due to the constant flow of air through the cylinders ( no throttle as compared to gas engines ) . There are some gas engines with a no coolant limp home strategy that shuts fuel off to alternating cylinders in an attempt to cool the engine.

When fully loaded, the cooling requirements of a diesel match or exceed that of a gas engine.