Top up radiator

Drain coolant, discharge A/C lines. remove front bumper for access. remove condenser, remove upper and lower hoses, remove hold down bolts on the top of radiator.

You can look at this 2 ways. If the hose is bound to the old radiator, it may be rotted in place and a poor candidate for reuse. You can always take the other end of the hose off of the motor and pull the hose off with the radiator. Then you can try to twist off the hose once the radiator is out of the vehicle.

Open front hood "frunk" remove radiator cover plastic.

Remove upper radiator bracket supports.

Disconnect radiator fan wiring connectors.

Remove upper radiator fan bolts.

Jack up front of the car. Place jack stands and use ebrake and some kind of wedge to stop rear from rolling backwards for safety

Remove lower radiator fan bolts and lower fans down and place to the side.

Connect the factory clear tubes to the drain nossle by the lower passenger side of radiator if you still have them if not use a large enough collection pan so it doesnt splash much.

Open top release. Top of radiator driver side.

Place your bucket under the drain nossle and open that up. Let the coolant drain. When finished close both nossles.

If the radiator has not been replaced before or if it was put back the right way. Youre radiator hose clamps will be facing downward. Use some long needle mpse pliers to remove hose clamps and then remove the radiators hoses from radiator. Keep collection bucket under.

Once both sides of radiator hose are removed. Gently lift the radiator forward and upward to release the bottom of the radiator from where it is seated and then lower the radiator out the bottom.

Reverse to install and make sure to follow factory manual for bleeding coolant system after

Sorry friend - heading to bed and heading out tomorrow - Try this link and then check the 1991 MR2 Repair Manual - Good Luck
http://manual.teq.org/

It hard to tell, Your thermostat may have stuck....i seen that before...Fan relay the same???

I've even seen a top radiator hose collapses when engine is running...

Radiator removal is not difficult if you pay attention to what you are doing. Difficulty depends on your skill level. (I've seen people who cant change a license plate, and some that can rebuild an engine. If you are one of the first, don't try it)You need to remove the bar that goes across the top, all hoses and lines, the plastic shroud, then without damaging it, lift it out.
Both chiltons and haynes have decent instructions.

The relay is located down at the left lower corner of the radiator support. Little flat box, like a box of matches. common to be bad.

get a Haynes Manual for your car from auto zone or advance auto.You will have to take off the front grill and it sets in your face. The Haynes Manual will show you step by step how to fix your problem........runjoe

the radiator cap is right there on top of the radiator at the front of the car....if nothing else and you still cant find it pour the stop leak into the overfllow and it will do the same thing

There is a special tool you need to purchase . It connects on your front motor mount located on top by radiator.. This is what is called the dog bone in the industry . The specialty tool is put in the place of dog bone mount and is adjustable whith vehicle placed in neutral... The tool pulls the motor towards the radiator giving you complete easy access and complete visibility for what you are trying to achieve