[R0CKKR4WL3R]

Did a search of the site and read almost all of everyone else's problems. Found some to be very informative and others could have been, but the thread stops with someone's insight, but no fix or remedy. Your idea sounded good, but "how"?

So on to my jeep...'01 Grand Cherokee Laredo 4.0 with 250,000 miles. Cooling fan is engaged ALL the time. Even when off, I need to remove the fuse or disconnect the fan plug. Up until today, the temp gage USED to read correctly. I found at 210-degrees, the radiator cracked and puked coolant all over the ground without warning. I was actually quite happy until that moment, that it was running great aside from the fan issue. This is the THIRD radiator in a month that I've had to install. Every day it has exploded, the temperature outdoors was 86-92 degrees and humid. Thus making me VERY unhappy!

The radiator, cooling fan, and waterpump were replaced before I bought it. I've had it a year and a half and now I'm at the mercy of the cooling system.
So far I've replaced the cooling fan once, the fan relay 8 times with some working fine and dying, others keeping the fan on all the time, and some not turning it on at all.
As I stated, the radiator has been replace 3 times (not by choice), and the thermostat replaced once.
The heater core is BRAND NEW, from Mopar.
At this point I'm about to replace the waterpump...again, and the Temperature control sensor.
I'm just trying to have a NORMAL RUNNING VEHICLE, in which at this point, I've forgotten what that's like to own. This is my first Jeep after 12 GM vehicles and I'm trying to build a loyalty to the brand, but finding it difficult as my patience is running VERY low. Especially after installing 3 radiators in a month and 2 in under a week. So now it's sitting as I use public transportation, which I hate, until the ENTIRE cooling system is brand new.
If the factory cooling system was touchy from the beginning, has anyone come up with a good aftermarket build that keeps the engine cooler than factory? Trophy truck style? I love building this thing, but I HATE repairing the cooling system every week!
Thanks in advance.

 

[R0CKKR4WL3R]

Also...Using Mopar bright orange coolant straight from the dealership.

 

[R0CKKR4WL3R]

No idea on reason for radiator cracking..if I knew that, I wouldn't come to this site for help. Tired of it cracking though!!!

The first time since I owned it, that it cracked, there was a 10" crack down the driver's side plastic tank. The second time, the crack was small and hidden, I assumed it was near the top, as I was able to limp the vehicle home by stopping, allowing to cool and adding fluid.
This last time, there was a 3" crack near the top of the plastic tank near the radiator cap, surrounded by stress marks or white lines in the plastic.
The cap came with the Jeep and shows no signs of damaging wear, although the release valve in the cap does not seem to exist.
Check all the grounds? In regards to the fan and relay and what else? I just want to make sure I don't miss anything. The relay ground might be a bit of a challenge due to it's location under everything. An access panel has been cut into the heavy plastic, but from there, I have no idea wear that wiring harness goes.
Does the relay use it's mounting bolts to help it ground out through the heat sync into the fender well? Was thinking there might be corrosion in the metal and the mounting location might need to be moved.

 

[R0CKKR4WL3R]

Wanted to add...when it overheats, I'm usually in a high traffic area, lots of cars moving slow and lots of red lights. On the highway, it does okay.
The temp gauge, up until yesterday, would go up to 240 and just under 260 before it would pop. At these moments I would pull over and let it cool before it would do so. It would release fluid from the reservoir while sitting for a few minutes. With the fan constantly running, the engine would cool within 20 minutes and I'd be on my way. Yesterday it just barely passed 210 and as soon as I parked it, the radiator popped with a 3" crack and stress marks up high on the driver's side plastic tank.

 

[R0CKKR4WL3R]

Replaced original fan with another Mopar fan. Yes, it is coming from the overflow reservoir, however, hasn't happened in the few days after changing the thermostat. Of course, it's only been a week and before the overflow reservoir could boil out, the radiator cracked instead.
Going to buy a new radiator cap, water pump and temperature control sensor. Thinking about buying a different Mopar fan along with a new relay as well. Just so they're matched, new fan and new relay. In the meantime, the jeep is parked for the week. I can't trust it to cross town if the temp gauge isn't registering the correct engine temp. I'll look into having a leakdown test of the head gasket done as well.
Thanks again for the help!

 

[R0CKKR4WL3R]

Carlos-

Previous owner had Jeep and on first hot day popped the radiator. He claims he replaced the rad, water pump and fan. Used Jeep for 2+ years before selling it to me. I racked up 25,000 miles before this issue has occurred with me.
I got it with a cracked heatercore that was seeping. The result was no heat. I replaced the heatercore.
As stated above, I'm letting the Jeep sit for a week until I can acquire the proper parts needed to rebuild the cooling system.
Upper radiator hose IS getting hot and lower is warm, or not as hot as upper hose.
Clogging doesn't seem to be an issue, as I replaced the lower hose yesterday no gel or solids visible. Upper I could see into...same thing. Radiators are new going in, so those definitely are not clogged, and the heatercore I can only assume is the same way. All clear.
Bubbling occurs MOSTLY right after I shut off the engine, I haven't noticed the bubbling otherwise, due to engine noise while running.
Oil does NOT look like a milk shake. Never a puddle on the ground, so it doesn't seem to be leaking any fluids. No white smoke or sweet smell from the exhaust.

Thank you Carlos!

 

[R0CKKR4WL3R]

Carlos,

FINALLY! Some good news! Thank you! I needed that! So water pump is operating accordingly....correct? No need to swap out?
When it comes to my screen name, you can just spell it out. No need to add the numbers in. It gives me a hard time, sometimes, when I'm logging in. Kicking myself for the choice.
I started the Jeep today with the cap off and let it run. The fluid eventually came up and then dropped down a bit before coming back up again. Unplugging the temp control sensor though, wreaked havoc. The engine kicked up in RPM's a bit and shortly after the radiator boiled over. Temp gauge was at 120 when disconnected, and within moments the radiator just erupted. Plugged in fuse for the fan, killed the motor and restarted a few minutes later and all was back to normal. I'm wondering if the temperature control sensor works intermittently. When it fails, I blow the radiator(s)? Unplugging it made the gauge read absolute zero. which never usually happens when I'm driving. What do you think?
I bought a Stant Radiator Cap with the red release valve today. Valve releases at 18 PSI.

 

[R0CKKR4WL3R]

UPDATE: Installed a new Temperature Control Sensor. Let it run for quite a while with no overheating, didn't even budge from the second notch. Let it run a while longer and still no movement in the needle. Checked everything over and no boiling over of the overflow reservoir.
No boiling over, no eruptions, no cracks in the radiator, no leaks, no drips....seems pretty solid. Could this be it? Temperature control sensor wreaked this much havoc?

If that's it, then on to the cooling fan issue and relay. Going to buy a new relay and quite possibly a new fan. I've heard of people saying the relay fails and something gets reversed. "What" is getting reversed? The fan is spinning the opposite direction? What exactly was meant by that? Looking to learn a little bit of how this relay is thinking.

Thanks in advance!

 

[R0CKKR4WL3R]

PROBLEM SOLVED!

Temperature Control Sensor caused a bunch of anguish and frustration. $30 part.
Once the Sensor was replaced, it took just one Radiator Fan Relay to correct the staying-on-all-the-time problem. (Instead if 8 in 2 weeks time)

Thank you to EVERYONE who provided support and ideas! You were ALL a great help!

 

[R0CKKR4WL3R]

Well, since I'm no expert, I am pretty good at guess-timating. So this is my educated guess...

After speaking with you guys, and getting input on this frustrating situation I was in, I followed a few steps and came up with the only thing I can possibly think might have happened.

Someone stated in checking for water pump failure, open the cap and let it run until it gets hot and the coolant starts to circulate. This will tell you that the pump is doing it's job.
After doing so, I decided to un-plug the Temp Control Sensor. Which I was also told would make the jeep turn on the fan. Since the relay I had kept the fan on all the time, I swapped it with one that wouldn't to see if it would still kick on.
Approximately 30 seconds after unplugging the temp sensor, the RPM's kicked up and the open radiator erupted coolant everywhere.

I figured that since the Temp control sensor tells the computer when to turn on the fans and do what it does to keep the engine running cool. That it was apparently failing, not at start up, but during road use, causing the radiators to build up pressure they couldn't hold.
I bought the new cap with release valve which seemed to help, but not sure if there is anything happening there. It still got hot, but I shut it down before I ended up buying a FIFTH radiator. However, the relay for the fan had a better response to the new Temp Control Sensor than it did for the old one. I never bought a new fan relay, I re-used one of the 8 I had and when turning on the AC it came right on, and turned off when I shut the Jeep off. The boiling over of the overflow reservoir hasn't happened at all and the loss of coolant has subsided, since the temp sensor was replaced.

As odd as it may sound, and trust me, it's ALL Greek to me, this is the only guess I can come up with as to how I managed to fix it. With ideas from you guys and a really good guess on my part. A $30 Sensor, if it weren't for warranties, might have cost me over $500 in radiators and give or take a head gasket or new replacement engine! Amazing! ...not to mention the mental anguish that went along with it all!

 

[R0CKKR4WL3R]

Makes sense. So in reality, I just had a cap the was holding in pressure rather than releasing it. An even cheaper fix at $6.50. Ah well, at least the fan, radiator, thermostat, temp control sensor, lower radiator hose and radiator cap are all replaced. Slimming down my chances of failure in those items.

Thanks again, because without the information you guys provided, I might not have been able to get through this. It was literally driving me crazy! You guys and this site are awesome!

 

[R0CKKR4WL3R]

Alright, so I found out today I have 2 pinholes in the top driver's side of the radiator about 3" from the filler neck. This is the same location as all the other radiators have been breaking from. Going on radiator number 6 in a month and a half's time. It ISN'T overheating anymore, but it is creating a problem for me. Any ideas? They are Autozone "Spectra" radiators.

 

[R0CKKR4WL3R]

Sorry. No pics available...Radiator already swapped out, installing in the morning. Hose is not obstructed. Checked it out.

It was literally 2 pin holes pissing a very thin stream at the back of the grille and driver's head light.
Spoke with Autozone clerks, and one immediately asked me if the tank keeps cracking. I was like, "WHAT?!?!" So apparently I'm not the only one to experience this.
I told them I've had it with replacing radiators, they all crack in the same spot, this one being the only one to get pin holes. Also told them I wanted out of the warranty circle I'm in, and was told if it happens to this one, bring it back, they'll refund my money and I'm out of the warranty trap I'm in. I'm looking to try another brand other than "Spectra", and it's the only brand Autozone sells. I was told of the possibility of cracks due to body flex and vibrations...I doubt its the problem.
I also bought a 16 PSI radiator cap over the 18 PSI I just bought for it. So hopefully that alleviates some of the pressure and stress on the radiator.
Again, the list of repairs:
-Water pump
-Heater core
-Thermostat
-Temperature Control Sensor
-Radiator (6 times)
-Radiator Cap 18 P.S.I.
-Radiator Cap 16 P.S.I.

The overheating has stopped, but now there seems to be a pressure issue.
What is going on???!!! If I had the money, I'd drop in a Trophy Truck cooling system! Indestructible!:lol:

 

[R0CKKR4WL3R]

Trans cooler is on the drivers side, same side as pin holes. Looking to alleviate the trans temp by adding a trans cooler in the near future. Think it's the transmission? Heating up the left side of the radiator enough to crack it open or cause the pinholes? Guy at parts store was surprised mine didn't come with one from the factory.
There weren't any signs of a weak spot on any of the radiators. No white discoloring of the plastic or damage to the boxes. They all seem legitimately in good working order. Any questionable markings might have made me questionable and not install it. But there was nothing.

 

[R0CKKR4WL3R]

You and me both! I just want to drive it...NOT fix it, especially fix the same thing 6 times in a month and a half.
New radiator is in this morning. I made sure NOTHING banged or touched the upper left corner of the radiator. So now if ANYTHING goes wrong, it's while the vehicle is in use. Not that it was an issue before, but why always in that corner??? I also don't see the issue with the trans cooler in the left side. Hopefully the new 16 PSI radiator cap will make a difference.
Unfortunately, I know I'll be back to respond to this post and most likely not with good news...trying to be positive, but so far only pretty positive I'll be replacing the radiator ....yet again....just how long will it take?
Maybe your right with the bad batch, We'll see.

Thanks for trying...:thumbsup:

 

[R0CKKR4WL3R]

Carlos,

Yes, I am using a wrench. Turns out, the one they sold me had TWO washers between the brass nut and the radiator tank, which caused the lower trans cooler line to leak coolant around it. Upper was normal. Didn't even notice until I returned it. Looks like a factory screw-up.

So far so good. Running at normal temps. Never gets higher than 210. At first it did, but I re-burped the system and caught a few stray air pockets. At that point it was at the 3/4 mark on the gauge at 98 to 100 degree outside temp. Made me nervous. Haven't had her in heavy traffic yet, and not confident she'll perform properly.

As far as the radiator fan is concerned... should it be sucking IN to the engine bay, or OUT of the engine bay? Right now it's blowing out. Which seems odd if you're driving forward, it's actually fighting the outside air.

Again, faulty relay is keeping the fan on all the time, which I guess is good on these hot days, but sucks every time I stop somewhere I have to pop the hood and pull the fuse.

I'm tired of fixing and swapping out items, I just want to drive it.

Thanks for the help. :thumbsup:
​

 

[R0CKKR4WL3R]

I knew it! No one I spoke to ever heard of this happening, so it was thrown on the back burner. Nothing seems to be crossed. Everything is original, so no wire splicing has taken place. What would cause this to happen on it's own? A bad module? Where is that located?
FINALLY getting to the root of the problem!

 

[R0CKKR4WL3R]

Going to try to flip the wires, just got home, and coolant is hot! So when she cools down, I'll see what I can do. Interesting info! I appreciate it!
I'm certain it's blowing out and not sucking in.
The fan only fits into the shroud one way, so getting it wrong during installation seems impossible. The wire harness clip only allows it to be joined one way. So that seems fool proof. Seems like a manufacturer flaw is the issue. Odd. I REALLY hope this solves the problem!

I'll keep you posted! Thanks again guys!:thumbsup:

 

[R0CKKR4WL3R]

Got the fan working correctly now. Used a receipt and it got sucked against the grill, and blown against the engine.
Got to get a new relay and HOPEFULLY problem solved! Tested 4 I have with Air Conditioning and only one of them work, 1 stays on all the time, the one Ive been using the whole time.