Replacing the radiator in a 1970 Mustang is a fairly simple task. There are very few steps, even with an automatic transmission. It should take less than an hour, even for someone with little or no experience.
Begin by draining your radiator. You will need something to catch the fluid, and you will want to be sure to store and dispose of the old fluid in a safe manner. Animals are attracted to it because it is sweet, but it is very poisonous. You will find the drain plug at the bottom of the radiator. Remove this, and keep track of it. You will probably need to install it in your replacement radiator. Next, remove the two hoses. One is at the top of the radiator and the other is at the bottom. If you are going to use the old hoses, they only need to be disconnected on the radiator side.
I recommend replacing the old hoses. To do that you will need to disconnect both ends. The top hose can be removed right away. The bottom hose should be disconnected from the radiator now, then wait to try and disconnect it from your motor until after you have removed the radiator. It will be easier to access then. Removing the old hoses can be difficult because they have usually gotten hot and are stuck on. First, loosen the clamps completely. Save these clamps, you will need them later. Try to pull the hose off. If it is stuck use a quick twisting, pulling motion to try and break it free. You may have to work on it for a while. If you cannot pull it off you will have to cut it off.
If you have an automatic transmission disconnect the transmission cooler lines. These are at the bottom of the radiator. This requires using two wrenches at once, and it will be the most brain-boggling part of the procedure. Be sure you do not twist these lines! Use one wrench to hold the line still and the other to loosen it. When you have these disconnected you will have a nut in each hole still in the radiator. Later you will remove these and install them in your new radiator.
Disconnect the shroud. It will be bolted or screwed to the radiator. You are almost ready to remove the old radiator now. There is a bracket on top of your radiator, holding it in place. Look at this from the front of your vehicle and you will find the bolts that hold this bracket in place. Remove those bolts. The bracket will come free from the car, and you can easily pull it off of the top of the radiator.
Now you can gently lift the radiator from the car. If you are keeping your old shroud, leave it there. If not you can remove it now, also. If you are replacing your hoses, do not forget to disconnect that old bottom hose from the engine now, and go ahead and attach the new one there. You will probably use the clamps you saved earlier. Slide them onto the hose, put the hose in place, then slide the clampdown to about one-quarter inch from the end of the hose and tighten.
Prepare your new radiator by installing the drain plug, attachments for the transmission cooler lines, and cap. Your new radiator may have come with these things already in place. If not, use the old ones. If you are replacing your shroud put it in the car now. Gently lower the new radiator into the car. Replace the bracket from the top, and bolt in place. Attach the transmission cooler lines, and hoses.
Bolt or screw your shroud to your new radiator, making sure the fan still has room and is not going to hit the shroud or the radiator. Fill your radiator with the proper mixture of water and anti-freeze. Half and half is a good mix. You can use an anti-freeze tester to check your mixture if you are not sure. Start the vehicle, and watch your fluid level. It will go down.
You need to keep filling it until it stops going down. Securely replace the cap, and check all connections for leaks. With an automatic transmission, check the transmission fluid in case any leaked out of the cooling lines.You need to keep
You are ready for a test drive!