Bad thermostat, air bubbles in the line, cooling fan relays not working, or the worst, bad head gasket. You can tell if it's a bad head gasket by white smoke coming out of the tailpipe, brown, sand-like gunk in the old radiator (and possibly new one) and oil mixing with your coolant.
Does your heater still work? If not, there's likely a bad thermostat or air bubbles in the line.
Make sure you reconnected all coolant temperature sensors. There is one in the radiator.
Check your starter it may be grounded when hot.
thermostat is not opening.
In the overflow tank as well as the radiator. You should not do this while the engine is HOT!
Other than an obvious external leak that you can easily see, you may have a blown head gasket.
thermostst is stuck
you broke something when you took the blower off .......
Worn or damage electrical motor, rotate the motor, movement should be smooth. You can always take it out and test it with the car battery. Be careful because if the motor is shorted it will become very hot.
check the distributor cap and rotor also check the coolant temp. sensor.. can cause a hard start condition when cold.
A common problem on Acura Legends (and other Acuras and Hondas in general) especially in hot weather is the fuel injection ("main") relay. In many cases, this relay is usually the cause of hard starting problems rather than the fuel pump. The fuel pump is misdiagnosed because many people are unaware of the fuel injection (also known as the "main") relay. The main relay is located under the dash, on the driver's side.
The fan under and behind the glove box is bad. I just bought one on eBay for $75. They are over 300 at the dealer.
Check all electrical connections battery cables etc. for looseness and corrosion Bad connection could cause spike and excessive heat Check voltage input and output of alternator' Check for a reverse polarity
It's not always the case if your car is overheating. This could be a sign the head gasket is bad but many other things could cause overheating as well. If your car got hot or runs hot it won't always require a new head gasket