'90 Talon With electrical problems

the statement is correct and the reason will be over pressure in the cooling system or boiling off the coolant. If you have a viscous fan hub then the hub will need replacing.
if there are electric fans ,check that they are operational
Have a compression test done to check for head gasket or cracked head

how long did you run it hot, chances are if you run it hot too long more than 10 or 20 minutes you are going to end up with a blown head gasket. Most cars usually restart after cooling off for 30 minute to an hour or by lett it cool off and topping it off with more antifreeze or even plain water if you continue to drive it without water for any length of time you are going to have a major head job ahead of you. If you run it to the point where you warp the head it will cost major $$ the way you tell this is check the radiator when it is cool and see if it looks like oil is mixed in with the coolant (usually looks like chocolate pudding ) or check the oil fill if there is thick chocolate mud like film on the filler cap chances are you have a blown head gasket and a warped head. time for an overhaul, can cause more internal problems as well water mixed with oil causes many mechanical problems. never ever run a car hot for any length of time pull over and sit until cool and top off with water if nothing else.. or have it towed.. not worth the major cost to repair when you blow a head gasket or warp a head. past experience 20+ yrs and working on automobile repairs.

have a compression teat done to check for head / gasket damage. When engines go to over heat the ring tension is lost and the compression falls . Heads crack and warp and gaskets blow

unfortunately this is probably correct if the car got very hot.
most new cars have alloy heads and if the car gets too hot due to cooling problem the head can warp.
a new head gasket and having the head skimmed flat again is one solution, the other is a new engine.

if you want a second opinion then most garages will be able to do a pressure test on the cooling system which would confirm a blown head gasket

If the head gasket did not seal from the previous rebuild the anti freeze could travel across the holes in the gasket when under pressure. The real problem you may be dealing with is a crankshaft that is wandering back and forth. The previous owner fixed the worn parts but may not have fixed the cause of the problem. I believe the lower end knock is probably caused by the wrong size lower connecting rod bearing (another potential disaster). If the car body is in good shape I would search for a good salvage motor or see if there is still a factory rebuild available. From what you describe there is probably no hope for your old engine.

Please check that the electric cooling fan operates when the engine gets up to temperature. Quite a common fault.

You can do a few quick checks: turn your heater on full blast in side the car and start the engine. As the engine heats up, you should feel heat blowing inside the car. If not, coolant is not circulating. No circulation can be caused by an air bubble caught in the radiator after it was flushed. Look inside the radiator to check the coolant level. It should be within an inch of the top. Don't remove the radiator cap when it is hot, you can be burned by steam. Leave the cap off and start the engine. As it heats up you should see movement in the coolant if you rev up the engine. If you find no circulation, the new thermostat may be bad or not opening at the proper temperature. Check the fan to be sure it is coming on as the engine heats up. The fan is electric and is designed to cycle on and off to maintain a steady temperature in the coolant. If it is not operating properly, engine will overheat. Hopefully when the radiator was flushed, the fins were also "blown out" to allow good airflow through the radiator, if not clean the fins with a good blast of a garden hose until all the dirt, dust and bugs are gone. These are simple tests. If the engine has overheated, there is a good chance you may have warped the engine head. This is beyond the repair capabilities of most drivers. Again, simple tests are: pull your oil dipstick. If the oil is frothy and the color of hot chocolate, you have water in the oil. If you can see spots of water clinging to the dipsitck, you have water in the oil. Check your new coolant. If there is oil in the coolant, (frothy brown layer or sheen on top of coolant) you have oil in the coolant. Either condition indicates you have a blown head gasket caused by warping the head by overheating. Blown head gaskets often cause overheating. The fix is to remove the head, have it planed and rebuilt and reinstall with new head gasket. This procedure is complex and expensive. Do it yourself requires a head gasket kit and planing and rebuilding the head. Expect that repair to exceed $600.00. Good luck, hopefully you will find a circulation problem.

Not generally, unless the engine's been run hot, if even only for a moment. If the head gasket is blown prepare for major out of pocket expenses because if the engine overheated it will bend every valve and usually warp the head beyond repair. I honestly hope this is not your problem, it's an extremely expensive fix. Hope this helps, good luck!

I replaced my whole engine foe $500.00 with a 90 day warranty from junk yard motor ran great and it only had 40,000 miles on it do not wast your time with just the head if you plan to keep the car . good luck

remove the spark plugs and turn the engine over could be the head gasket if so the stop leak additive is a tempory soloution to a perminent problem. replace head gasket