03 KJ rad removal, install and system flush

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New Member
Aug 28, 2013
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Ottawa, Frozen North
Hi all,

I didn't find a write up that I liked for this task so thought I'd better contribute to the community. I've found so much help on here. :happy107:

My rad failed at the top (!!) from one of the horizontal runs, not at one of the endtanks like most do. My little KJ puked its coolant all over the place.

Before you start, make sure you have everything you need. I picked up a Koyo OEM replacement for $169 at my local auto parts place, Dayco upper/lower hoses for $30 and a new Stant rad cap for $8. You will need a minimum of ~7L of mixed coolant (buy one full strength bottle). If you are flushing the system (recommended), you can buy an extra bottle. Also, make sure you have plenty of distilled water on hand which you can also use for the flush and for mixing up your coolant (50% minimum, but up to 70% coolant to water ratio).

I have an electric fan on my KJ, so if you have a mechanical or hydraulic fan, I have not included any instructions on their removal. Sorry folks.

Also, ensure you have all safety gear on hand and USE IT. Big men swallow their pride. Small men lose an eye.

1. Let the Jeep cool down. The coolant system is under pressure when the coolant is hot and even more so in a KJ (compared to other vehicls) which is pressurized to 16 psi.

2. Leave the cap on. The cap is on top of the coolant expansion tank on the passenger side, near the windshield.

3. Set up a drain pan underneath the driver's side of your Jeep under the drain on the driver's rear side of the rad.

4. On the drain attach a hose to the spigot and direct it into the drain pan.

5.a) Using an appropriate wrench, open the drain valve by turning the hexagonal plastic 'bolt' counter clockwise until it funs freely. Let it drain while you complete some of the other steps. Once it slows down, remove the cap on the tank and let it drain some more. Once that has slowed down or stopped, close the valve and empty the pan.

5.b) You now want to move the pan over to the psgr side and remove the lower rad hose - you may need vise grips to compress the hose clamp. This gets messy. If possible, use a wide funnel, otherwise it will run all over the bottom side of the bumper and create a coolant rain that is as wide as your Jeep...don't ask how I know!! lol You'll want many old rags, or a couple rolls of paper towel in case you spill...

6. Remove the battery (10mm bolt on the locking bar at the rear side of the battery, 2x 10 mm nuts on the terminals)

7. Remove the battery tray. You will need to do this to slide the rad out. 3x 14mm nuts, one will need an extension as it is down by the horn mount (under the tray). The other two are easily visible.

8. Remove the bolts holding down the top metal brace located just under the leading edge of the hood. 4x 10mm

9. There are two rivets holding the hood latch mechanism to the metal brace. You can leave them attached and 'deal' with manoevering around it, or dremel/drill them out and replace with bolt/net later. I chose to dremel them out.

10. There are 4 Torx screws holding the top of the plastic grill in place - one above each headlight, the other two above the grill. Remove them and lean the grill towards yourself and then lift it up. There are four hooks at the bottom of the grill which link into the bumper skin, no fasteners.

11. Looking at the front of the vehicle through the grill, remove the 2x 10mm bolts securing the small power steering cooler located on the driver's side.

12. Pry out the plastic fasteners holding the edges of the rubber pieces that attach to the vertical supports under the plastic grill - two vertically on each side of the rad.

13. Push/pull the rubber pieces out of the way to access the long 10 mm bolts securing the top of the rad to the metal brace in the engine compartment. You will need an extension for this.

14. Look toward the bottom of the rad from the front of the vehicle to see where the external transmission cooler (if equipped) is attached to the rad. You should be able to remove these 2x 10mm bolts with an extension going *through* one of the holes in the bumper where two of the grill 'hooks' go through to attach. On the driver's side, it helps to use a wobble bar, the psgr side is fine with a regular extension.

15. Lift the cooler so that the tabs come up and out of the hook holding them to the rad. If you do not do this, you will pull the cooler up when trying to remove the rad from the top.

16. Remove the 2x 10mm bolts holding the top of the AC condenser (if equipped with AC) to the rad.

17. Use some sort of pry bar or long screwdriver to pry the rubber piece off of the mounting points located on the rad for the transmission cooler and the AC condenser. If you do not do this, the rubber pieces will prevent you from lifting the rad out from above.

18. Looking from above the rad, unclip the red tab on the wiring harness for the fan. Then press down on the main tab of the connector and slide the plug apart. Remove the 2x 10mm bolts holding the top of the fan to the rad. Then finaggle that fan out of there.


20. Lift and manoever the AC condenser out of the hooks holding two tabs at each side of the condenser at the bottom. You will need to pull the rad up to get the bottom rubber feet/posts of the rad out of the rad support running under the rad.

Viewed from the side the condenser tabs sit in the hooks on the front of the rad to support the condenser. In the simple diagram below, the R's represent the vertical portion of the rad (ignore the dots, spacing problem). If you do not take it out of the hooks, the condenser will prevent you from removing the rad from above.
| | R
| | R

20. Before you start pushing and pulling on the rad, you might want to remove the connector mounted with 2 10mm bolts to the rad support on the driver's side. You can mash this up pretty easily if you don't. I'm not sure what it is, perhaps a ground?? Someone fill me in and I'll update the write up.

21. I assume you have removed all hoses from the rad now, if not, remove them now and get them out of the way.

22. Now the tricky part if you have AC. If you don't have AC, well this will be easy. Manoever the rad towards the driver's side of the vehicle and upwards at the same time to get the upper mount to clear the upper rad support. The psgr side mount will be stuck under the high-pressure AC lines. If you leave that connector (mentioned in step 20) in place, it might get bashed. Also watch for the lines near the bottom of the rad and anything else in the way. You will need to move and shake it diagonally and this way and that way. I can't think of a good way to describe it, but may the force be with you!!!

22. Once it is out, transfer the upper rubber supports and the lower rubber supports to the new rad. If you have an internal transmission cooler, you will have to attach the lines to the rad. If you do not, you can plug them with electrical tape, doesn't matter much since it's a separate system from the coolant.

23. Lower the rad carefully into place in the reverse awkward order. Get the tabs of the AC condenser seated in those hooks, get the bottom of of the rad (with rubber bits!) seated in the lower rad support, slide the tabs of the external transmission cooler into the other hooks, reinstall all mounting bolts, attach the grill, etc. Double check that everything is reinstalled and all hoses are reattached. Ensure your hoses are as round as possible. If they look 'squished', rotate one side where it is attached to the rad or the vehicle until it is 'round' again.

24. If you want to do a flush of your system, fill it with distilled water (unless it is below freezing!!!), ensure you have enough in there, it takes about 7-8 L. If you only got about 3-4L, gently squeeze the upper and lower hoses to circulate the water. Once you have sufficient volume in it, run your Jeep to normal operating temp with the heat on HOT and fan on high, let it cool somewhat, then drain it through the spigot at the bottom of the rad. You may need to do this several times depending on how crunchy it is in there. I did two cycles of water, one cycle of mixed coolant (60%). Dispose of this responsibly.

25. Once you are satisfied with the clarity, ensure it has been fully drained of water/coolant, refill with a minimum of 50%, max of 70% coolant to water mixture. Run it to operating temp, heat on HOT, fan on high. Let it cool and check the coolant level again.

You are ready to go.

Now :grd: :icon_smile:

Function > Form
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Full Access Member
Jun 25, 2014
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Tucson, Arizona
Is it possible to remove the fan without removing any hoses?
I need to replace the electric fan.


Full Access Member
Mar 3, 2013
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Townsend, MA
Yes. You may need to take the top crossbar off though but that is easy.

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