Radiator Leak

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berick06

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Hey Everyone,

Novice mechanic here, whose run into a bit of an issue with my 05 Rubicon. The other day I noticed that my radiator coolant was flowing into the overflow reservoir when I turned the engine off (making a boiling sound). I figured it was due to a bad radiator cap. However, after replacing the radiator cap I immediately developed a significant leak which now appears to be coming from the bottom of the radiator. I did verify that it is not overflowing at the cap. Any ideas what might be going on? Thanks in advance for the help!
 
It sounds like you have a radiator leak. In which case I'm pointing out what it sounds like you already know.

Is the coolant actually leaking out of a crack or a pinhole you can see in the radiator?

If so, replace it with one of the following OE Mopar radiators:

Part number: 55037652AA (Manual Transmission)
Part number: 55037653AC (Automatic Transmission)

Also, for the radiator cap, make sure to use Stant #10234.
 
Thanks Chris, I appreciate the input.

I can't see for certain where the leak is coming from, but it almost looks like a crack along the bottom because it's not just dripping out of one spot.

Any idea why it would start happening right after replacing the cap? Was the faulty cap just masking a bigger problem?
 
Since I have to replace my radiator, I've decided to replace the rest of the coolant system (radiator, thermostat, and water pump). I've managed to disassemble everything with only a few minor pains (stupid fan clutch). The thermostat housing and the water pump pulley are looking a bit rough. Is there a recommended method for cleaning those, or do most people just replace them? Do you also recommend replacing the serpentine belt since I have it off?

Thanks for the help everyone.
 
I would change the belt while you're in there.

The old cap may have been opening at lower pressure so replacing it let the leak show up because it stayed sealed at higher pressure. Just a guess.
 
berick06 said:
Since I have to replace my radiator, I've decided to replace the rest of the coolant system (radiator, thermostat, and water pump). I've managed to disassemble everything with only a few minor pains (stupid fan clutch). The thermostat housing and the water pump pulley are looking a bit rough. Is there a recommended method for cleaning those, or do most people just replace them? Do you also recommend replacing the serpentine belt since I have it off?

Thanks for the help everyone.
Click to expand...

I would just replace them, especially if there is no history of them having been done and they have hire miles. Even more so if they look "rough".

I would replace the serpentine belt if it has visible cracks in it.
 
Chris said:
Part number: 55037652AA (Manual Transmission)
Part number: 55037653AC (Automatic Transmission)
Click to expand...

Adding to these part numbers, you need to pay attention to the AA, AB AC identifiers; check your radiator to make sure you get the correct connections or you will be asking how top modify the setup.
55037652AA: Manual Trans./No transmission connectors
55037653AB: Auto Trans/Slip on/Clamp style connectors (hose slips over a fitting)
55037653AC: Auto Trans w/ Quick connectors
 
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I just installed a Mopar radiator last week. The quality if far better than the Sprectra junk I just recycled that was a year and a half old. A new Stant cap and thermostat to finish the job.

TJ parts are rapidly disappearing in the Mopar supply chain so grabbing one of these is good insurance. Most OEM's average 9-12 years of parts support before they leave the market to the jobbers.
 
Had basically the same thing with my jeep. Turn off, coolant boiling out of the radiator into the overflow. Replaced the cap, sprung a leak from the water pump. Ended up replacing the waterpump/thermostat. I just used a basic rotary cleaning tool for the mating surfaces on the block and thermostat housing until they were nice, new shiny metal.

Pretty sure the increased (back to stock) coolant system pressure also put a pinhole in my heater core as well but that's a fix that's going to have to wait due to the amount of time it'll take me to take apart the dash just to get to the damn box.
 
If it is the original rad, I'd bet it is rotten at the bottom header. We replaced mine 2 years ago, the bottom corner was rotten to the point it fell apart.
 
Thanks for the input everyone. Greatly appreciated. I'm hoping to have everything put back together this weekend. I'll let you know how it goes.
 
LCL-Dead said:
also put a pinhole in my heater core
Click to expand...
Definitely buy quality parts.

I had a new heater core installed in April, it was leaking in December, 8 months later so new core under warranty in January. Here we are 2 months later and it already leaking.

Thankfully Tune Tech in Spokane stands solidly behind their 12 month warranty and will be replacing it again when I am in Spokane for a Rotary Convention. Fabulous service from Tune Tech, they drop everything for warranty work.

Not sure what brand the parts were but Tune Tech is using a different part this time.
 
Cooling system overhaul complete...and successful. Only issues were a fully cracked thumbnail from trying to loosen the fan clutch, and waisting an hour trying to figure out what the front axle vent hose was and where it plugged into. 😁

Thanks for the help everyone!
 
So back from Spokane and another heater core replacement. While in the shop they found a leak in the 2 year old rad. While pressure testing it it split apart so, even tho it was installed 2 years ago with a 1 year warranty, they replaced it under warranty.

Have to love a shop which just does things right.
Tune Tech on Monroe in Spokane gets all my work.
 
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