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Radiator Leak

5K views 19 replies 6 participants last post by  Frango100 
#1 ·
I have a radiator leak in the fins of the radiator. I am going to replace it. Looking for any tips out there. Are any radiators better then the next? Should I go ahead and replace the hoses? It's an 04, 4.0L with 84K on it. Thanks
 
#2 ·
First of all, can you see if the leak is caused by for example a.stone? Because it can.be that the cause is electrolysis. If the cause of the electrolysis is not solved first, you could end up with a leaking core soon again. You have to measure with a multimeter in the volts setting and put one probe on the negative side of the battery and the other in the.coolant at the radiator fill opening. Not sure anymore.about.the limit, but i thought that if its above 0.5 V that electrolysis will cause damage.
I bought a Spectra Premium from Rockauto.com for my jeep and it performs well. It comes.assembled, so you only have to change it out.
Its.always a good idea to change thermostat, hoses and radiator cap at the same time.
 
#3 ·
I was thinking about changing the thermostat but wondered if I should go with a cooler one. What's the stock thermostat, 180 degrees? If I went with a 160 degrees one would I benefit from it because it would run cooler?

I can see fluid from the fins on the front left, if looking at it. Also you can see a slight spray on the back left, again looking at the engine, and fluid will be everywhere on the left side of the engine bay. Looking at the rear of the radiator, looks as if the top two rows of fins are angled downwards.

Another question I have is the line on the bottum of the radiator is for tranny fluid. If I have a leak does that mean its possible the tranny fluid is low now too? My coolant reservoir was damn near empty but now I'm wondering if I should check the tranny fluid as well. What do you think?

Even if the hoses are good, you would change them anyways?
 
#4 ·
My thinking about the thermostat is when a cooler type would be better, why would jeep not use it from the beginning?
The tranny cooler fluid is separated from the coolant, so when you have a coolant leak, the tranny fluid is not affected. Only with a catastrophic failure of the radiator it could maybe happen, but normally not in cases like yours. But you could easily check the fluid level to have a good feeling about it.
When the radiator hoses are still the original ones, i would replace them. They are not expensive and could prevent problems lateron.
Eventhough they maybe look ok, they probably have become stiffer and will seal off less. I changed mine at least together with the radiator.
 
#6 ·
I'm going with the stock thermostat, 195*. Which gaskets will I need?

I was going to flush the whole system before installing the new stuff. You think its a good idea or a waste of time? My only concern is water sitting in the system and corroding the interior of the system.

How much coolant will I need?
 
#8 ·
I am also about to install a new radiator in a WJ 4.0. let us know how your repair goes. I have a Spectra Premium on deck for install this Sunday. I have read extensively on the install, only things im unsure of is as folllows: does the e-fan come out as one assembly still attached to the radiator, and im unsure of how to disconnect the AC compresor from the radiator avoiding opening the pressurized system. Also, is the headlight removal necessary, I know the upper crossmember and hood latch must be removed. I do plan on a small amount of pipe dope on the threaded tranny cooler threads, this has been debated before....keep us posted and I will as well.
 
#9 ·
Flushing is in fact a must, it will remove all (or at least most) of the debris and all old coolant. Best is to do a reverse flushing, against the normal flow direction. Small openings (ie for heater core tubes and alike) could be (partly) clogged and with the reverse flushing you have a change to work those small particles out again. Corrosion due to the water in the system is not a problem, since you will fill the system up with coolant, which normally is a 50% mixture with water.
Not sure about the seal for the thermostat. If its the same as for the 4.7, then its just a round seal which first around the thermostat. Yoy can buy it together with the thermostat.
On the 4.7 i have a hydraulic fan and that one comes together with the radiator. I also didn´t knew it and was trying to get the lower bolts out, which was not an easy thing, but at the end i discovered that it was not necessary to remove first.
 
#11 · (Edited)
Alright, my radiator is installed. it was a pain, but done. I used a little thread sealant on the tranny cooler lines, no leaks thus far. Upper and lower hoses appear to be leak free as well. I filled new radiator to top with fresh coolant and topped overflow tank to full, capped radiator and ran to operating temp watching efan kick on and feeling heater hoses and upper hoses for warmth which all checked out. Heat is good too. Do I need to run engine with rad cap off to purge any remaining air from system. I followed the drain and fill instructions from WJJEEPS.com which says to only add to overflow tank after initial fill of radiator, and to never run with cap off, as this is an 'open' cooling system. Will the air purge itself by warming up and cooling down, only adding coolant to overflow reservoir as needed? This is how it was explained on the wjjeeps procedure, but other sites have said run it with cap off up to operating temp, this seems dangerous as it should overflow out of the rad fill neck. Thoughts? I am not overheating, the temp flucuates just a bit once it gets to 210 then it drops right below 210.
 
#12 ·
After the initial bleeding no need to run without the radiator cap anymore. The air will stay in the upper part of the radiator, which is the filler neck. As soon as the engine heats up, the coolant expands and the radiator cap pressure relief valve will let coolant and air escape to the overflow reservoir. Next time it cools down again, coolant will be drawn back from the reservoir into the radiator. It can take maybe a few warm up/cool down cycles to get rid of all the air.
 
#13 ·
thanks frank. Yep, while cooled completely i opened cap and poured maybe 1/2 qt more coolant into radiator, and it was full once again, capped it. Been great so far. The fittings on the transmission cooler lines were identical to OEM and i don't anticipate any seepage.
 
#20 · (Edited)
The reason that it leaks with the radiator cap installed is that it will build up around 18 PSI of pressure, so you will have more change to discover a leak then. When you are sure its leaking from the gasket, a little RTV or liquid gasket on the gasket faces should solve that.
Heat on or off should not make any difference, since the coolant always flows through the heater core.
 
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