Novak Conversions Jeep Wrangler TJ radiator

Radiator Exploded (Need Advice)

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cuttinAR

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Been trying to diagnose a radiator issue on my '02 tj and apparently the radiator was dissatisfied with my effort and decided to blow today. A quick rundown and if anyone could offer some advice on what caused the issues and my planned repairs I'd appreciate it.

This is mainly a trail rig and I don't drive it too often in the summer. Noticed last spring quite a bit of gurgling noise when shutting off the engine after rides. Also deal with heat soak issues in the summer even after insulating the injectors. Head gasket was replaced earlier this year.

After driving last week I noticed the reservoir was empty and it was essentially steam going from the radiator to the reservoir. So, I decided to get a new thermostat and start with replacing that. Gauge reads slightly over 210 and has since I've owned the Jeep. I'm kicking myself for not changing the radiator fluid last year when I bought the Jeep but I've noticed it rusted pretty bad over the spring and summer this year. I decided that before I installed a new thermostat I'd do a flush with Thermocure which I began earlier this week. Went ahead and put a new cap on and drove it a couple days with no issue or boiling and it's hot right now, damn near 100 degrees and humid.

Planned on the last drive to be this afternoon to get enough time for a good flush. Spent a little bit on some gravel roads and was only going 20 mph which is what I think reveal the problem again. Stopped and heard gurgling so I popped the hood to hopefully let it cool. It was boiling into the reservoir pretty good, I was trying to figure out how to relieve the pressure cause I figured what was about to happen did. Boom! Radiator split right down the middle!

So, I now plan on completely replacing the cooling system because I don't trust it. What could the cause be? Stuck thermostat? Faulty water pump? Clogged radiator? Recommendation on what to replace? Assuming all Mopar?

Thanks for the help.
 
Step 1: replace radiator
Step 2: done

Just kidding, gurgling is a sign of a pressure leak, most often the radiator cap. Radiators are know to blow, it happens to everybody. Replace the radiator and the cap then do a pressure test to check for other leaks. Mopar radiator if you can find one, I don't really care about the other stuff but some do, do what you can afford.
 
At a minimum I'd personally replace the cap, upper and lower hoses, thermostat, thermostat housing, if you filled out your damn profile the fan clutch if you have a 4.0 and obviously the radiator. Probably not the water pump, it's never the water pump unless it's leaking.
 
pagrey said:
At a minimum I'd personally replace the cap, upper and lower hoses, thermostat, thermostat housing, if you filled out your damn profile the fan clutch if you have a 4.0 and obviously the radiator. Probably not the water pump, it's never the water pump unless it's leaking.
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Dang take it easy I'll get the profile going! lol. Yes its the 4.0.

On the water pump can the impeller not be bad and you wouldn't know even with no leak?
 
I did find the cooling system parts FAQ post so got that going. Also just replaced the cap prior to the explosion.

Anyone have an idea on what caused the pressure?
 
cuttinAR said:
Dang take it easy I'll get the profile going! lol. Yes its the 4.0.

On the water pump can the impeller not be bad and you wouldn't know even with no leak?
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Glad you have a sense of humor, I am an ass for sure. I'm sure the impeller can fail but it is really rare and the other stuff is really common, I am super lazy so I go with the common stuff.
 
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pagrey said:
The radiator is know to burst a seam at the top due to age alone, it doesn't need any help.
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Yep I get that but I'm trying to determine what the increased pressure cause was so the next one doesn't do the same.
 
cuttinAR said:
Yep I get that but I'm trying to determine what the increased pressure cause was so the next one doesn't do the same.
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Mine seemed perfectly fine until the seam gave way and exploded. I was on Golden Spike and it was 105 degrees that day.
 
cuttinAR said:
Yep I get that but I'm trying to determine what the increased pressure cause was so the next one doesn't do the same.
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Your system pressure is at 18psi set by the cap. You can't change it. If the next radiator gets old and can't handle 18psi it'll blow too after 20 years. Not a bad deal overall, not perfect but not bad. I think @mrblaine carries fiberglass tape, like drywall tape, and epoxy to fix it on the trail, good advice if you go out in the sticks.
 
pagrey said:
Your system pressure is at 18psi set by the cap. You can't change it. If the next radiator gets old and can't handle 18psi it'll blow too after 20 years. Not a bad deal overall, not perfect but not bad. I think @mrblaine carries fiberglass tape, like drywall tape, and epoxy to fix it on the trail, good advice if you go out in the sticks.
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So the boiling over into the reservoir is just a function of the cooling system not functioning properly? Could be radiator, thermostat, etc.

No smoking gun? Just a smoking radiator.
 
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Your radiator is dead, lets move on from that one. I don't know exactly what happened but ya, cap is key to the operating pressure of the system and you need to check for leaks after you've replaced what is obviously busted.
 
pagrey said:
Your system pressure is at 18psi set by the cap. You can't change it. If the next radiator gets old and can't handle 18psi it'll blow too after 20 years. Not a bad deal overall, not perfect but not bad. I think @mrblaine carries fiberglass tape, like drywall tape, and epoxy to fix it on the trail, good advice if you go out in the sticks.
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I do not. I do tell folks who call me from various places across the US how to do that repair to get back to camp or home. Mesh drywall tape, 5 minute JB, acetone based brake cleaner, coarse sandpaper.
 
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mrblaine said:
I do not. I do tell folks who call me from various places across the US how to do that repair to get back to camp or home. Mesh drywall tape, 5 minute JB, acetone based brake cleaner, coarse sandpaper.
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I just replaced a radiator that was fixed exactly that way and it held for who knows how long...it was definitely an older repair..the entire top seam was cracked
 
cuttinAR said:
I did find the cooling system parts FAQ post so got that going. Also just replaced the cap prior to the explosion.

Anyone have an idea on what caused the pressure?
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You put a new cap on an old rad which brought the pressure back up where it should have been, and the old weak rad exploded.
 
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