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Unread 05-12-2014, 12:32 AM   #1
Smitherd
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Join Date: Aug 2013
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Wj WJ Radiator Swap

Howdy friends, me again.

My 99 WJ (4.0 liter, inline 6) has been overheating recently and spewing coolant. Periodically (not all the time) I will park and a few cups of coolant will spill out from under the front grille and fascia onto the ground. The other day I popped the hood, and found a nice spurt coming out of the side of the radiator. It appears the seal around it is bad from overpressurization, but I could be wrong about that.

The radiator is definitely bad (now), but this leads to another question: is it possible that the water pump is also bad, perhaps being what caused the radiator to go in the first place? The first mechanic I talked to said it was the water pump, so I'm wondering if either he was incorrect or if it could be both.
The other question is this: if I replace the water pump, do I also need/have to replace the fan clutch? I've been told "definitely," "maybe if you feel like it," and "no reason to do that" by three different people. Any help would be appreciated. Thank you!

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Unread 05-12-2014, 01:58 AM   #2
kfxnando
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If you have an overppresurisation situation then I would look at fixing that as well

had a similar issue on a different vehicle
on hot days no issue on cooler days sometimes there would be coolent loss even overheating
went through two custom made exra cores radiators and kept blaming the manufactures of the radiators

when I eventually pulled the heads found the steal ring on the gasket had a crack and would seal sometimes and sometimes not
hence the over pressure conditions
Now that 4l also has a similar set up like my other motor of cast iron block and head

So maybe you have more then one issue

and just so by the way, I also replaced the water pump on that motor and did not solve the issue

hope this helps
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Unread 05-12-2014, 06:36 AM   #3
Terminal
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Check for bad fan relay and fan. Once it overheats under pressure it will eventually split the radiator at the seams. Common problem with these Jeeps. Been there done that.
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Unread 05-12-2014, 07:59 AM   #4
kfxnando
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Quote:
Originally Posted by Terminal View Post
Check for bad fan relay and fan. Once it overheats under pressure it will eventually split the radiator at the seams. Common problem with these Jeeps. Been there done that.
In no way am I disputing what you are saying

however isent the radiator cap suppose to limit the pressure to what I think the new caps are 17psi
My old one was if memory serves me right 18psi
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Unread 05-12-2014, 08:22 AM   #5
MuddyWJ
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Quote:
Originally Posted by kfxnando View Post

In no way am I disputing what you are saying

however isent the radiator cap suppose to limit the pressure to what I think the new caps are 17psi
My old one was if memory serves me right 18psi
True unless the cap is bad. On the other hand if the tstat is bad it'll cause all sorts of pressure so you'll want to replace it as well. Make sure to boil test it before putting it in.
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Unread 05-12-2014, 08:49 AM   #6
Terminal
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Quote:
Originally Posted by kfxnando View Post
In no way am I disputing what you are saying

however isent the radiator cap suppose to limit the pressure to what I think the new caps are 17psi
My old one was if memory serves me right 18psi
"Once it overheats," the poorly designed and manufactured radiators will split where the plastic end caps on radiator are glued and clamped together because it can't handle the extreme heat. This area will fatigue until it splits. The steam will then push out through that split "under pressure."
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Unread 05-12-2014, 11:33 AM   #7
kfxnando
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Ok then

so if those radiators quality is so poor, then here is another solution
And have seen it being done

have the plastic tanks replaced with custom aluminum radiator tanks and welded onto the aluminum original core - presuming that those radiators have an aluminum core

copper cores - copper tanks

hope this helps
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Unread 05-12-2014, 12:08 PM   #8
HVACNY
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Quote:
Originally Posted by Smitherd
Howdy friends, me again. My 99 WJ (4.0 liter, inline 6) has been overheating recently and spewing coolant. Periodically (not all the time) I will park and a few cups of coolant will spill out from under the front grille and fascia onto the ground. The other day I popped the hood, and found a nice spurt coming out of the side of the radiator. It appears the seal around it is bad from overpressurization, but I could be wrong about that. The radiator is definitely bad (now), but this leads to another question: is it possible that the water pump is also bad, perhaps being what caused the radiator to go in the first place? The first mechanic I talked to said it was the water pump, so I'm wondering if either he was incorrect or if it could be both. The other question is this: if I replace the water pump, do I also need/have to replace the fan clutch? I've been told "definitely," "maybe if you feel like it," and "no reason to do that" by three different people. Any help would be appreciated. Thank you!
No,you dont have to replace the fan clutch. Good luck on the repair..
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Unread 05-22-2014, 06:21 PM   #9
Smitherd
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The plot thickens. Decided to do the radiator and water pump, skip the fan clutch if it's still good. This particular Jeep has TWO fans: an electrical one right behind the radiator under a shroud, and a mechanical one immediately behind that one. Got the whole front end disassembled, but absolutely COULD NOT get the mechanical fan clutch off the water pump. We tried FOUR different "fan clutch wrenches" from AZ and O'Reilly's, we hit it with a propane torch to heat it, EVERYTHING you could imagine. Finally, we gave up on that and just got the water pump off with the fan clutch, blades, and pulley still attached. We weren't sure we would be able to get them apart, so we decided to try to replace the fan clutch, blades, AND pulley. Some Googling and forum reading led us to believe two things:

1. The fan blades and pulley (NOT the clutch) are basically unattainable because they are discontinued.
2. The mechanical fan appears to be an optional part, because it was only installed on 99 WJ's with towing packages.

So, if #1 is true, I doubt we're getting the blades and pulley, period. They're not coming off that old one without an act of divine intervention.
And if #2 is true, should we just put it back together with a new water pump, and leave the fan clutch/blade/pulley assembly out of the equation entirely? And if so, does this mean that the Jeep can no longer tow things?

Thanks for any advice you can give.
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Unread 05-22-2014, 08:03 PM   #10
fast540
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Cut enough of the water pump away to get the impeller in a vice and put a big wrench on the fan clutch it'll come off
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Unread 05-22-2014, 08:05 PM   #11
fast540
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Really use a cutoff wheel on the nut part then remove the pieces and replace the clutch u just cut up. No such thing as "can't" remove
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Unread 05-22-2014, 10:34 PM   #12
gold01wj
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Mine broke free after a few smacks with a ball peen and punch on the nut in the direction to loosen. That being said i agree with the above theres always a way to get stuff apart you just got to get creative some times
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Unread 05-22-2014, 11:37 PM   #13
DDog1
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Not sure about taking the clutch fan apart/off however, I would recommend you replace it/put it back on if you can. It came as part of the tow package. The reason I suggest putting one back on is that in other threads on this WJ forum, the electric fan relays seem to tend to fail for folks (although mine never has (knock on wood)...and I've owned it since I bought it off the lot '99 4.0. ) Additionally you want to minimize the potential for overheating as that can lead to other problems with these WJ's like a cracked head...again more threads on this issue on this forum. If you're only depending on the electric fan and it fails then you're SOL...so, I like the security of the mechanical fan if only as a "backup" to help prevent the bigger problems.
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Unread 05-22-2014, 11:46 PM   #14
DDog1
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Oh and no it doesn't mean you couldn't tow something however when towing you make the engine work harder which guess what, makes the engine generate more heat...thus the reason for the mechanical fan to help more readily dissipate the heat....You would be more likely to overheat without it if you were putting allot of strain on the motor towing something heavy..
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Unread 05-23-2014, 12:48 AM   #15
akoutdoors1
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Confession: When I tried to get mine off of my 4.7 the other day I was turning it the wrong way. It is regular, right-hand thread. Hitting things with a hammer isn't usually what i'd recommend. I ended up making a tool that works like this: http://www.amazon.com/Gates-91060-Wa.../dp/B00BNX9U4K

Good luck.
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