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Blown headgasket?

I was told by a mechanic that I have a blown head gasket. What happened is that when I went to have my oil changed a few days ago - the service folks noticed that I had a cracked radiator. I took the car to have the radiator replaced - I got the new radiator installed and when I started it up - coolant started bubbling up - a bad sign, which led the mechanic to tell me that I have a blown head gasket - now, I have blown a head gasket once before - at that time the car overheated, ran rough and had white steam coming out of the tailpipe - this time around - no nothing other than a small crack in the radiator - the temperature never rose past normal, no steam from the tailpipe, does not run rough, no visual signs of oil mixing with coolant - could it be something else other than the head gasket? If exhaust was being blown back into my radiator, why did not my thermostat register such extreme heat - a stuck thermostat? Any assistance would be helpful? I guess the mechanic needs to run a compression test, look for hydrocarbons to be 100% sure, or having coolant bubbling out of the radiator upon ignition definitive proof of a blown head gasket/

The hydracarbon test is only a few bucks and only takes a few minutes. It is strange that it was left for you to notice the coolant bubbling and not reported by the mechanic who installed the radiator.

Are you sure the bubbles are exhaust gases? You can get bubbles of air that is being purged from the cooling system. With the radiator repair comes a complete drain of coolant and pockets of air can take a while to work out of the system. You might have a bad head gasket, but I’m not certain of it given what you’ve posted.

I agree. I’d be suprized if it were more than simply air bleeding out from the radiator replacement. I simply don’t see in the post any sign of a blown headgasket, and air pockets bleeding out would not be unusual for the work done.

The mechanic who did install the radiator did point out to me the coolant bubbling up and the and one more thing - the radiator hose was hot and firm immediately after ignition - but will certainly do a hydrocarbon test - thanks for the advice. I really appreciate your comments.