Many cars display head gasket symptoms when the problem is just a clogged or blocked radiator. So I recommend going through the following procedure after the purchase of your new Vintage or Classic car and do so every two years.
Buy some radiator flush; make sure it is compatible with alloy heads or far cheaper use washing soda, not baking soda.
Follow the instructions if using a bought flush. If using washing soda – with the engine cold remove the rad cap and put a handful of the soda into the rad and replace the cap.
Turn the heater up full and drive around until the engine reaches normal working temperature or if your neighbours are friendly leave it running in the drive. If you have an electric fan wait until it turns on. Then turn off the ignition and allow the engine to cool down.
It is preferable to undo the bottom rad hose to drain the system (drain plugs easily break) as you get a greater flow and subsequently more crud should come out. In really bad situations where maybe the water galleries in the block are clogged, undo the top heater rad hose and using your garden hose (not in times of drought) to force water through until the water runs clear out of the bottom rad hose. The same can be done through the top of the rad until the water runs clear out of the bottom.
If money isn’t tight now would be a good time to replace all your pipes. If you are doing so try getting silicon based ones, dearer but they last longer. You should also check your thermostat.
Remove the thermostat from its housing taking care not to damage the gasket and noting which way it is facing (use your mobile camera). Fill a pot with hot water (better get permission first) and bring it to the boil. With the thermostat hanging in the water and a thermometer, watch as the temperature rises that the thermostat opens at the correct temperature (it is written on the thermostat). If it sticks, doesn’t open or if you are in doubt replace it, they only cost a few euro.
Clean all metal surfaces, smear on a small amount of light grease. I prefer to use Hylomar. Fit the gasket, the thermostat (the right way round) then the housing cover and tighten the nuts/bolts to the correct torque.
Before refitting the hoses use very fine wet/dry silicon carbide paper to clean off the metal hosepipe connections, wipe clean and using light grease smear a small amount onto the metal pipes to help to ease the hose pipes back on.
Refit the hosepipe/s making sure not to over-tighten the clips (replace the clips if they are rusty or damaged) as they may cut into the pipes.
Refill the system with the correct mix of antifreeze or as I do with my classics use full strength Blue coolant and no water. I have never had any problems. Do not however use Pink coolant, it is designed for modern engines and don’t be tempted to mix them even in a modern car.
Refit the rad cap. Start the engine with the heater on full until it gets to normal working temperature. Check for leaks. Turn off the engine and allow it to cool down then check the coolant level in the rad and top up if necessary.