I'm going to post this since the rads. on these cars like to go bad often for various reasons. Feel free to suggest improvements/add info that I may have missed. It's 1:17am and I've been up since 5:30 yesterday so I may have missed something, lol..
Since my stock rad. died I decided that while it was out it was a good time to look around for an upgrade. Might as well go bigger/better if it won't break the bank. After digging through some old posts here and a few other sites I found that there is a 1 3/8" core rad. that will swap into any W-body with little modification and loss of room under the hood. This was done on my 2000 GP GT. I don't have headers yet but don't see an issue for any of the guys that do. Also, this will require that you have the 99+ coolant bottle mounted on the pass. side strut tower as the overflow tube is on this side of the rad. For you 97-98 guys there is are threads on this site that detail how to swap over to it. Do a search, it works, trust me.
The parts list I used is as follows:
1. Murray Radiator from OReillys (Lifetime Warranty)- 1 3/8" core- Is listed for a 1998 Monte Carlo w/ the 3800. Just choose the HD cooling. Their site lists 3 different radiators. One is the stock 5/8", a 1", and the 1 3/8". Word to the wise would be to bring a tape measure with you when you pick it up so you can measure it in the store to be sure you got the correct one.
2. 1 gallon of your choice of coolant. Since I run conventional green, that's what I went with.
3. New radiator cap. Not a necessity but I discovered someone installed a 15lb cap on it, and stock is 16.- $7.99 at Autozone
4. Dayco LOWER radiator hose from Autozone. Part # C71700- $13.99
5. New longer bolt for the center of the fan assembly where it bolts to the top edge of the rad. You'll see it when you remove the fan assembly. The stock bolt is a M6x1.00 according to my tap and die set. The replacement I got was 1" longer than stock.
Now that you have the parts, lets move on to removal/install...
1. Remove radiator support bars on both sides. One covers the airbox and the other the battery.
2. Disconnect Battery (both cables) and remove it from the engine bay.
3. Remove airbox assembly. You can leave the tube on the throttle body but the entire box has to come out. The ECM is inside the bottom half of the box so gently move the wire harness from the side of the box and lay the ECM on the inner body where the airbox was.
4. Drain radiator into a large container. I didn't mess w/ the petcock, just pulled the lower hose off and let it drain into my pan. Personal preference and a lot quicker.
5. Remove both dogbones from the radiator core support.
6. Disconnect the wiring harness from the fans to the main loom. Should be a large gray plug up near the top between the fan shrouds.
7. Now that the radiator is empty, remove the lower hose entirely, and disconnect the upper hose and move it out of the way of the fans. I chose to leave mine on and just fold it back some. You could also remove it from the thermostat housing as well.
8. Remove the 3 bolts holding the fan assembly to the radiator. One on each side near the edge, and one in the center up under the edge of the core support. Should be 10mm bolts.
9. Disconnect the transmission lines from the bottom of the fan. There was a plastic holder on mine that they cliped into.
10. Disconnect the low coolant sensor harness.
Once this is completed the fan assembly should be free and ready to come out. NOTE: Remove your oil dipstick and set it aside until you get the fans out and reinstalled at the end as it is possible you may hit the dipstick and crack it like many of them already are. Just don't forget to replace it before driving! I pulled my fans out towards the drivers side. Just pulled up on that edge and worked it to the right and up. It is kind of heavy and can have some sharp edges on it so be careful.
11. With the fans out, you can disconnect the 2 trans. lines from their fittings on the rad. When you remove the clip for the snap-in style lines be sure not to loose it. A small retractable magnet can come in handy if you loose one. They will most likely end up on the lower air dam or on the bottom of the core support somewhere.
12. With all lines and hoses disconnected you can now remove the mounts on either side of the tank. There is one per side. Then simply push the radiator towards the motor and lift it out. There are 2 rubber feet on the bottom that you need to save as well once it is out. They are to fit the radiator properly and give it the proper mounting height.
With the old rad out, now would be a good time to clean out the A/C condenser coil. I used my air compressor to blow it out from the backside. Quite a bit of junk was removed. Just don't bend the fins on the condenser. If any are bent from removing the radiator then straighten them out.
Now, onto the install of the larger radiator.
Here are some pics to help illustrate..
Side by side comparison of the old on left and new on right
Here is a shot of the new radiator core measurement
13. Transfer the rubber mounting feet to the new rad. May need some WD-40 or something to help install. Remove the 2 trans. cooler line fittings from the old rad and install on the new one. I used some teflon tape on them to ensure no leaks. Remove and clean the low coolant sensor from the old rad. Notice in the pic below that the new rad. has the coolant sensor port on the side of the tank, not the backside. Mount it so the plug is facing UP as shown in pic 2 below.
Now you can install your new radiator. It drops into the original space. Install the 2 metal clips that are used to hold the fans on. One per side. Make sure the rubber mounts are all the way in the core support at the bottom. Once in, reinstall your side mounts to hold it in place.
14. Reinstall the 2 clips to the transmission lines if you have that style. I chose to wait to reinstall the lines until I had the fans back in place. You can do what you feel comfortable.
With the lines back in place, reinstall the fan assembly being carefull NOT to bend up the fins on your new radiator. Bolt it down on both sides and use the longer top bolt.
Reinstall the upper radiator hose. Reassemble and install the airbox/ECM. You can now put the drivers side core brace back into place.
Now I'm sure you've noticed that the lower hose mount on the new rad. is angled inward towards the motor, not straight out like your stock unit. This is where the new lower hose comes into play. Test fit the new hose to be sure you have it at the proper angle and not upside-down. It should be pretty obvious once you look at it. Cut a 1/2" off the end that connects to the waterpump outlet. This will ensure that the bend at the bottom of the hose is not too severe and does not create a restriction in the system. This also allows safe passage of your A/C compressor pulley and the belt. This is a cut-to-size hose, so cut however much you need, or none at all.
With all hoses and lines back in place, reconnect the fan assembly harness. You can now also reinstall the battery. I had to unbolt and swing the fuse block out of the way a bit to get enough clearance to snake the battery back in. It is tight but will fit. Make sure the hold down is completely removed for this. Once in replace the hold down and reinstall your brace.
Reinstall the dogbone mounts to the core and use a ratchet strap or the like to rock the motor forward enough to get the bolts back through.
Check over all your work to be sure there are no loose ends. Especially check the airbox as mine was being a PITA and wouldn't go back together correctly at first. If everything looks good then reconnect your battery after cleaning both the terminals on the battery and the cable ends.
Fill up your new radiator w/ the gallon of coolant and then fill the coolant bottle with water. This should give you the proper mix once you get done topping it all off. Then simply start the car and let it warm up to temp w/ the heat on full blast. Once the thermostat opens then use the bleed screw on top of the thermostat housing to bleed out the air. Once you see a solid stream of coolant then it should be good to go. Leave it run and check for any leaks. If none are found then go take a drive to get everything filled. Let it cool off overnight and then check the coolant level again in the rad. and the bottle and top off as needed.
Below is a completed shot from top to show clearance between the fans and stock N/A exhaust. And no, I did not measure it, but can if someone requests it.
FordMan77
