Chrysler Repair: overheating and stalling, head gasket leak, radiator fluid

Question
Hello, pete, my chrys conc 99 lhs recently has been overheating with boiling radiator fluid, i put some seal blocker in it and it remain to boil over and run hot. diags from dealer reports radiator cap and fan assembly, could this be a blown headgasket and if it is, is it worth it?

Answer
Hi Kendra,
I'm Roland just for the record...but Pete is co-expert. There are several ways to distinguish a head gasket from a radiator cap and fan assembly issue.
If the pressurization/bubbling sounds/boiling over starts soon after you start the engine, and assuming that the cooling system was filled to begin with, then that is indicative of a head gasket leak. If you get clouds of white (water) smoke out the tailpipe when you start the engine that is another clue. The last test would be to have a radiator shop test for exhaust gases in the coolant coming from the overflow or the radiator cap opening which would confirm a head gasket leak.
On the other hand, if the heating up and subsequent boilover is gradual, no white smoke, no gradual loss of fluid from the cooling system other than what boils over, and the fans don't come on as the temp gauge moves to the red, then you have an issue with the coolant temp sensor or the fan relay, or the fans or their fuse.  
Either way, a '99 is new enough to warrant a repair, all other things being ok. There is no point in sacrificing a good vehicle and engine because of a head gasket leak. If it is diagnosed as a leak, you might want to remove the spark plugs and find out which one(s) are wet or which holes blow water when you crank the engine with the plugs removed. Or measure the compression to find a low reading cylinder. Then you know which side of the engine the leak is located at. And it might be the case that the simple partial loosening and then re-torqueing the head bolts could stop the leak if it was due to loose bolts rather than a frankly torn gasket. That is a long shot, but it has worked for me on several vehicles.
So make some observations and feel free to write back for further discussion.
Roland