Overheating issue......head gasket??

1992 Cherokee 4.0, 190,000 miles. New radiator, thermostat, fan clutch, hoses, water pump and still it overheats. My problem is worse/faster at interstate speeds and will heat the gauge off the scale and boil over. Around town with the A/C off, it stays at 230 or so if it is cool outside. There is no coolant in the oil. When I fill with coolant and the engine is running, air bubbles continually come out of the radiator and do not stop. Head gasket? I have not yet tested the coolant for HC's but what do you guys think?

You could take it to your local garage and have the do a test. They should have the equipment to test for "the presence of exhaust products" in the coolant. From that reading the mechanic can tell you if it a bad head gasket or not. That is the definitive thing to do.

You did not mention this in your post. Did you replace your radiator cap when you installed that new radiator? Before I would go to the mechanic I would change out both the radiator cap and the thermostat.

The over heating has damaged them, that is a no risk bet. My local radiator shop told me once if you get a thermostat to 225F one time you can do damage to it. Once it is damage it may open too soon or too late. The cap may not be holding pressure, the over heading has damaged the spring.

I'd get the thermostat at the dealer, the radiator cap is up to you but might be as easy to get both at the dealer. If you go aftermarket on the cap buy a Stant brand radiator cap. Should be able to get both the thermostat and cap at the dealer for less than $20. This is not a time to go cheap on parts.

He's already replaced the t'stat so i don't think that's the problem. The radiator cap could be though, so I think it should be replaced with a new OEM unit.
The only way a blown head gasket can cause overheating is if coolant is being lost into the oil or into the combustion chambers (and exhaust). If it's going into the oil, the oil will emulsify and look like a chocolate milkshake. If it's going into the exhaust, you'll see steam coming out of the tailpipe. It's less common for exhaust gas bubbles to get into the coolant through a blown head gasket. It's more likely to happen if the head's cracked.

Actually, I did replace the cap with a new 16 pound stant.

pressurerat said:

Actually, I did replace the cap with a new 16 pound stant.

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Are you losing coolant? If you are, you've most likely got a blown head gasket. If not, I suggest you completely drain the cooling system and give it a thorough flushing. I know the radiator is new but the insides of the engine's cooling passages could be coated with 12 years' worth of grunge, so don't be surprised if your coolant is rusty coloured.
If neither of these measures work, try running the engine without a t'stat. If it runs dramatically cooler, install a new t'stat. Like the others said, your t'stat could now have been damaged by overheating.

While your at it, use only water. The thermal transfer is better than with antifreeze. Once you solve the problem, add the antifreeze back in.