Coolant boiling over, radiator not pushing?

REDLYNER

REDLYNER

Mall Crawling Race Rig
Joined
Oct 31, 2008
Location
Mountain Island
So I just got my jeep back and I've been driving it all over the place the last few days to get everything (steering) broken in and have come across a big issue. The jeep over heated in my neighborhood- never done that before in 11 years of ownership. That was yesterday, then today I drove it to the gym and when I jumped out, I could here gurgling. I popped the hood to see my coolant tank was boiling and it was completely full (usually it is at the full line, half way down the tank). Drove it from the gym to the gas station and now the coolant was just pouring out of my overflow tank. I was able to get it home, but I'm thinking the radiator isn't pushing the coolant through.
I have a call into Griffin for a race radiator, but thought I would toss it to the forum to see if any of that sounds familiar. I'm looking at replacing the radiator, thermostat, and shroud (torn up from EMC) just for a refresh.

Thoughts?
 
Sounds like you're going at it from the shotgun approach.

What's the gauge say? Is it running in a normal range? Does it overheat when sitting still, or when moving, or both?

Is the cap holding pressure? How does the fan clutch feel?

Radiators don't push anything. They radiate. So long as it's not leaking, there's probably not anything wrong with the radiator.

Thermostats generally stick open, not closed. If, by chance, it were to stick closed, then the engine would get extremely hot and the radiator would remain cool.

The fan shroud probably has little to do with the issue.

Were the radiator and overflow confirmed full after it overheated (and cooled back off) the first time?
 
Shawn-

Regarding new parts: I'm running a 14 year old radiator and thermo, it's been through a lot the last few years, I figured it is just a good to get some fresh parts in there. The last few East Coast races have been mud-fests, so I'm thinking now is as good of time as any to upgrade.


The overheating: never overheated on the street before. Normally it runs like 210, then yesterday it jumped up to 250 or so. I turned the heater on full blast and it dropped it back down to 220 or so.

Today it ran hotter than normal, but not into the 250 range. But today I had the gurgling and boiling over/spewing. Just some basic research was showing possible head gasket holes, but I wanted to see if anyone here had similar issues (common problem I'm not aware of?)
 
Two of my old ZJ's did the exact same thing. The radiator cap was old and not holding enough pressure.
If i was you i'd just buy a new cap and see what it does. I'm almost willing to bet that's your problem.
 
REDLYNER said:
Regarding new parts: I'm running a 14 year old radiator and thermo, it's been through a lot the last few years, I figured it is just a good to get some fresh parts in there. The last few East Coast races have been mud-fests, so I'm thinking now is as good of time as any to upgrade.
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If you want to spend money on parts and not fix the problem, have at it.

So long as the radiator is clean and not leaking, it should be fine.

I have had more trouble with brand-new thermostats being bad, so again, unless its not opening at all or staying stuck open, I wouldn't mess with it.

Check the coolant level, the radiator cap, the water pump, go from there.
 
Is it overheating at low speeds or when you are going down the highway? An improperly functioning radiator will cause it to run hot at highway speeds and around town.
What kind of fan are you running, and is it actually running?
Easy to check with a electric fan, just get the jeep warmed up and look to see if its running. With a mechanical fan, get it warmed up and then use a broom or something to try and stop it. If the hydraulic clutch is working right, it won't stop, but if its weak or worn out, you will be able to stop it. I actually just did this on my car a couple days ago because the AC wasn't working well around town, and it was a result of the fan clutch lagging too much and not getting enough airflow over the AC condenser (radiator/engine temp was fine).
 
jeepinmatt said:
Is it overheating at low speeds or when you are going down the highway? An improperly functioning radiator will cause it to run hot at highway speeds and around town.
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Temps seem to be ok at highway speeds. Also, not sure if it matters, but again, when I turn on the heater the temps go back down. Stock fan, stock setup.

I'm going to take it in for a pressure test this morning to hopefully eliminate the head gasket scenario.
 
My money is on fan clutch or radiator cap first. I'd also suggest mud packed into the radiator, but I know that Jay cleans the Jeep with a toothbrush after every race.
 
REDLYNER said:
Temps seem to be ok at highway speeds. Also, not sure if it matters, but again, when I turn on the heater the temps go back down. Stock fan, stock setup.

I'm going to take it in for a pressure test this morning to hopefully eliminate the head gasket scenario.
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The heater use and vehicle speed improving the situation would point to a fan or shroud issue.
 
shawn said:
My money is on fan clutch or radiator cap first. I'd also suggest mud packed into the radiator, but I know that Jay cleans the Jeep with a toothbrush after every race.
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That's actually one of the issues Shawn, the Badlands race was an absolute slop fest with mud and water and despite me spending a half hour at the pressure washer the night of the race, it still left Indiana filthy and went straight to the shop for the hydro steering install. I didn't get the jeep back until a month later, so I just now was able to start the cleaning process.


I'm sitting at the shop right now getting emissions inspected, I'm going to have them run a compression test while it's here just to eliminate other scenarios. On the 5 mile drive to the shop I did 50 to 60mph with no over heating, including a few stop lights, but I did smell the coolant about half way here.
 
Check your water pump, mine was doing the exact same thing the past two weeks. I knew it needed a water pump but hadn't changed it. Last time i drove it, the bearings in the pump went out and was puking coolant. I put a new pump on and a 180 thermostat. Going good now. Still thinking about a ebay two row radiator with being on the beach only now.
 
shawn said:
The computer won't go into closed loop until it hits operating temperature, which is north of 190F.
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This is true, I'm not really worried about that. He should stick with OEM thermostat, but for me I want it to stay cool when I'm running down the sand or cruising around looking at bikinis.
 
So far so good..... Radiator cap seems fine, no leaks can be found, and initial testing shows the head gasket is ok. Looks like the main culprit was mud caked in the condenser. We've had a hose on it for awhile breaking up the mud and after a few test drives, no over heating. I'll probably have to experiment with it and do some climbs or idle with the nose up in the air to see if I can get it to replicate. Yesterday I was flooring it and manually shifting gears at redline (getting some 0 - 60 times.... they were slow), so maybe I can try some more of that to get the coolant boiling again.

alh6.googleusercontent.com__KuzuTCaDJqE_VACod5pG0QI_AAAAAAAAFL4_6PoX0muCKJU_s805_emissions1.JPG





Also, for reference, here is a shot of where I trimmed about an inch off the upper section of the shroud (old engine mount setup had the fan blades clipping the plastic on hill climbs)-

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So after some testing (about 10 miles in the heat), the jeep didn't overheat, but when I got home, I could hear the gurgling again. I popped the hood and could see the coolant boiling in the reservoir. It wasn't overflowing, or even raised, but it was definitely bubbling.

I'll throw in a new t-stat this weekend and see if that helps.
 
Did you pressure test the cooling system? Not the radiator cap, and not an engine compression test. Use the radiator cap tester on the radiator, listen for any coolant leaks bubbling out the hoses, radiator, Tstat hsg, water pump, etc.
Stock fan...is that the viscous fan clutch? No mentions yet if you confirmed that was locking up whe. Hot, that will surely cause overheating. Drive it aroun to get it nice and hot, then jam a pizza box in the fan. If the box stops the fan, the clutch isn't locking up and you won't pull any air.
 
Radiator cap. Gurgle after drive not during is the cap. While driving in a working system the pump is constantly flowing fluid so the pressure rises from heat just a bit . So it builds to a point then maintains as temps even out. On the other hand when you stop it spikes a bit because you sit still with no air. Thus a weaker cap is revealed. A pressurized system also increases the boiling point. So now the suddenly escaped fluid is allowed to boil (lower Pressure). Now spewing down the road and overheating I'd look deeper. T-stat, fan clutch, water pump in that order. This excludes the obvious dirt dober core and chewed up fan shrouds. And a blown head gasket may pressurize a radiator but doesn't mean excessive heat. So lots of pressure and no temp spikes would seem like a head gasket.
 
Yes, if it's not overheating per the gauge, but it's still letting coolant into the overflow, that's because the radiator cap isn't doing its job. And yeah, like Warriorwelding said, you can run a higher PSI cap to raise the boiling point of the coolant and buy yourself some extra heat capacity out on the margin.
 
WARRIORWELDING said:
Radiator cap. Gurgle after drive not during is the cap. While driving in a working system the pump is constantly flowing fluid so the pressure rises from heat just a bit . So it builds to a point then maintains as temps even out. On the other hand when you stop it spikes a bit because you sit still with no air. Thus a weaker cap is revealed. A pressurized system also increases the boiling point. So now the suddenly escaped fluid is allowed to boil (lower Pressure). Now spewing down the road and overheating I'd look deeper. T-stat, fan clutch, water pump in that order. This excludes the obvious dirt dober core and chewed up fan shrouds. And a blown head gasket may pressurize a radiator but doesn't mean excessive heat. So lots of pressure and no temp spikes would seem like a head gasket.
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Yep.
Aaaaaand, make sure you bleed the cooling system before you crank it up. How do you do so on a 4.0? Easy. Unhook the heater hose from the thermostat housing and begin filling up the radiator. Keep filling until coolant comes out of the heater hose port on the thermostat housing. Then reconnect the hose and continue to top off the coolant like normal.
Water pumps do a remarkable job at pumping fluid, not air.
 
Suggestions on leak?

I replaced the radiator cap and the thermostat and that seems to be helping a little- although, in my frustrations of tearing the first gasket, I forgot to bleed the system per Jody's instructions. It's not overheating, and the boiling in the reservoir tank is less, but not altogether gone. So today I just let it idle in my driveway for 15 minutes or so after a cold start and sure enough, I could smell anti-freeze. I saw a small puddle on the ground and this is where it looks like its coming from:

alh5.googleusercontent.com__tfNCEcDQCJo_VBctL2WapVI_AAAAAAAAFP4_TNef7DP7mTQ_s640_leak.JPG


No signs of leaks from up above dripping down, appears the fluid is coming from this section. Looking like the radiator is fubar?
 
Sure looks like the radiator is leaking where the tank and body is connected. Pretty common place for them to leak on a TJ . Easy fix at this point luckily!
 
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