[v8volvo]

Try doing the "bubble test" to see if you are leaking compression into your cooling system. You can still do it even with the coolant out, as long as you put the hoses back on to seal the system up again.

Here is how you do the test: get a medium-sized glass jar or other container and fill it most of the way with water. Start the D24T. Make sure you have all the hoses attached and tightened enough so that the system is airtight like it's supposed to be. The expansion tank cap should be on and tight. Now, disconnect the little breather line that runs from the top of the expansion tank to the top of the radiator. Leave one end connected to the rad and stick the other end into the jar of water, while using your finger, a cap, etc to seal off the opening on the expansion tank. Let the engine run for a little while while watching the hose. (Don't run it too long without coolant in it or it will overheat...) If bubbles are coming out of the end of that hose, then your headgasket is blown, since the bubbles are combustion gases that have leaked out into the water jackets.

The heat exchangers do fail sometimes, but not as often as headgaskets. ;-)