Radiator Spewing Black Foam from Top

[lionheartsails]

1999 Mystique, V6, 150,00 Miles. Driving 70, noticed what I thought was white smoke in mirror, immediately exited freeway when engine cut off, and realized it was steam from the under the hood. Once I opened the hood, what would be best described as steam and a black/grey foam was spewing from the left (driver) side port on top of the radiator. A little foam and a lot of steam for the next 15 minutes. Level & color in the coolant reservoir tank are the same as when check recently. Oil level / color are good. No other areas of leakage.
Thoughts / Suggestions on what might have caused this issue?
Are the 2 nozzles on top of radiator designed to be pressure relief valves? (only steam from diver side port).
I figure need to replace radiator, hoses, thermostat, water pump, transmission cooler lines.
Anything else I should replace, look at, or be concerned about? .

 

[larsofvt]

My first guess would be head gasket failure pressurizing the coolant system and causing your upper radiator hose to rupture.
The two "nozzles" are just studs for radiator attachment to the car's structure. The attachment mounts keep the radiator isolated from vibration.
You could replace just the hose, fill the system and start the car to look for bubbles in the overflow tank.

 

[gmorrell]

The two small hoses that run from the upper radiator hose and the passenger side radiator top tank are just de-gas lines to return trapped air and steam from the engine and radiator to the recovery reservoir.

A radiator shop (a real radiator shop, not an auto parts store, real radiator shops are unfortunately going the way of the dinosaurs...) can pressure test your radiator. Most plastic tanked radiators fail (leak) either where the tanks are crimped to the core, or a plastic tank will crack on a flat face where the stress is greatest.

At 150K miles, it would be a good idea to replace upper and lower hoses, radiator, pressure cap on the recovery reservoir and refresh the coolant, Zerex G-05 is the right coolant for these cars.

The trans cooler in the radiator tank might have leaked, but the trans cooling loop runs at very low pressure, lower than the radiator should normally run, so I'd expect to find coolant in the auto transmission, rather than the other way around. You might want to check the condition of the trans fluid.

These engines also have factory water pumps that fail by allowing their plastic impeller to dissolve, so coolant doesn't get pumped around like it should and the cooling system overheats on the highway. It would be a good idea to check the water pump, new Motorcraft (Ford) replacement water pumps can be found reasonably priced at The Mothership (Amazon).

You might have a head gasket leak, but you're going to need a properly working, not leaking cooling system to effectively diagnose that.

EDIT: I know this is true for SVT Contours, probably true for regular Contours as well: The radiator and fan shroud come out through the bottom, do enjoy that...

 

[lionheartsails]

No Title

My first guess would be head gasket failure pressurizing the coolant system and causing your upper radiator hose to rupture.
The two "nozzles" are just studs for radiator attachment to the car's structure. The attachment mounts keep the radiator isolated from vibration.
You could replace just the hose, fill the system and start the car to look for bubbles in the overflow tank.

larsofvt, It is not a hose that is leaking. Steam was Definitely coming from the center of what you are calling studs for attachments. I can put a probe down the center of the diver side at least 8", while the other side approximately an inch.
Engine Oil and Transmission fluids look as expected.

 

[blu_fuz]

You have radiator failure if anything is coming out of that. All that black plastic 'stud' is an extrude section of plastic that supports the radiator position by poking through the rubber grommet around it. If fluid is leaking from there, the plastic black bellow of the sides of the radiator are damaged.

 

[gmorrell]

I can put a probe down the center of the diver side at least 8", while the other side approximately an inch.

Yep, that's a radiator failure, go buy thee a new radiator. When you mount the new one, make sure it has some free play in the upper and lower rubber isolators, the radiator has to be able to expand and contract without incurring any mechanical stress, or it will fail again, that's why it's soft-mounted in rubber donuts.

 

[lionheartsails]

Thank you for the replies. Radiator, hoses, thermostat, and water pump have been ordered...