Blown head gasket? Opinions plz.

[ResurreXJion]

Scored a low mileage 4.0, 1996.

Runs GREAT. It has been sitting for 2 years before I got it. Today, I went to check the motor out real good, and I let it run for half an hour.

Temperature shot up to 230, it boiled over, so I shut it down.

THE ANTIFREEZE WAS BLACK!!!!!!!!!.....Not black like oil and water mixed like a blown head gasket would be. (The oil is still crystal honey clear) but black like.......exhaust smoke, maybe? It is definitely antifreeze, (checked to -10 degrees) but the color has me worried.

I did a compression check (plugs were fairly clean) and the compression was between 130 and 145 for each cylinder

Could the head gasket be blown between the cylinder and the water jacket? Or maybe just crap floating around in the coolant systemn from sitting?

 

[Jeepm@n]

I've seen where the hoses have deteriated and have left a black sooty coolant. My reccomendation would be have the coolant system flushed and checked. Yes you can have the two still mix (oil into the water and not water in the oil). Oil is usually at a higher pressure then the oil and it could be a heat related mixing issue.

 

[albush1]

How did all the plugs look during the compression check? If it were mine, I would flush cooling system really well, back-flush it in fact, and then put a new thermostat and hoses on it. If the radiator fins looked plugged, then either buy a new one or have it boiled out, but they are so inexpensive to begin with. My guess is that it's the same radiator. Also, the fan clutch is likely weak, so a new one might be in order, just inspect it to see if it's working properly.