Overheating problems

[Mayooo]

So I've developed a little overheating problem. Went to work last week everything was fine. On the way home the temp never went into the red but it boiled over. My setup is a 3 core alumi. Radiator with 3 10" efans. A highflow water pump and all new hoses. Also run a remote oil cooler and a remote trans cooler as well as all of my A/C system removed. I've been running this setup close to a year now and have never had any problems. Nothing is blocking my radiator, all fans are running and have tested the Tstat.

I'm going to try another Tstat tomorrow but just not convinced that it will fix the problem.

What it's doing is getting up to temp at the start of my trip then the Tstat opens and you can see the temp drop. Tstat closes and repeat.. Now after a few cycles of the open and close it starts to cool down less and less. Meaning when it opens at 210 it drops to 185, opens at 210 drops to 190 opens at 210 drops to 200. ect.ect. To the point the temp just keeps rising.

I'm completely stumped with this.. Any ideas?

[GoneWithTheWind]

It sounds like your Thermostat is getting tired. And it sounds like the rest of your system is working like it should.

[GoneWithTheWind]

It sounds like your Thermostat is getting tired. And it sounds like the rest of your system is working like it should.
I'm sorry but that's all I got.
In the olden days, thermostats would sometimes get old, wore out and stick open.

[Mayooo]

I'm sorry but that's all I got.
In the olden days, thermostats would sometimes get old, wore out and stick open.

Yeah agree. It's a new thermostat.. Only about a month old. Installed it when I did my flush. I understand new stuff can go bad that's why I pulled it and tested it..

[Mayooo]

So I haven't done anything to the cooling system yet.. Today it worked like a charm. Seems like when I mess with the radiator cap is when I start getting problems?

[OldFaurt]

So I haven't done anything to the cooling system yet.. Today it worked like a charm. Seems like when I mess with the radiator cap is when I start getting problems?

Radiator caps have a little vacuum valve built in. look at the part of the cap that goes in to the radiator. there should be a little round metal disk that you can easily pull a little ways from the rubber seal if it has any gunk dirt or stuff under it or just dangles from the cap, clean / replace it. that allows the overflow tank contents to be pulled back into the radiator when it all cools down. if it does not seal, you will blow most of your antifreeze out but not pull it back in causing growing air pockets in the head. then it gets hot!
Have a look. also the lower hose can collapse at higher RPMs if it is getting old or in your case, a high output water pump??? some of the older ones had a spring inside that stopped that but newer ones don't. see if it is squishy (tech term) if it is soft, replace!

Also, some people think "distilled water only" is best if you don't have freeze issues, that's crap advice as antifreeze also raises boiling point of the fluid. other wise it boils at 212F degrees, Straight ethylene glycol's boiling point is 387F and 50:50 is around 265F - 285F and with a good sealed system held to +15 PSI raises it another 20F - 30F. So, Check that cap!, & the overflow tank and hose as well !
Good luck!

[slvmart]

With radiator caps running under $10, it would seem like a good thing to swap out. If you want to check if the cap is functioning properly, you can either use a coolant pressure tester or I would suspect that any auto parts store can check it for you.

Also .... http://www.speed-wiz.com/calculations/chassis/coolant.htm

[GoneWithTheWind]

Did you get your overheating problem fixed?

[Mayooo]

Nothing yet.. Checked the water pump and replaced the Tstat and cap. Some trips it gets hot others it's normal. I have also noticed it's been running rich as well..

[GoneWithTheWind]

I'm at a loss, I don't know enough about these computer systems yet. I'm used to setting my own dwell, idle, timing. You say it runs rich at times? Could it also be running very lean at times? Have you had a look at your plugs to see how they're burning? I think if things are getting hot in your cylinders then your plugs might be a bit white. could be a part of your problem?

[Mayooo]

I just replaced the coil, wires and plugs about two months ago.. I'm starting to lean towards a map sensor and going to rerun my vacuum lines with new hoses.

Yeah I'm pretty mechanically inclined and have been working on cars since I was a kid with my father. But I'm stumped as well..

[downsy]

Do you have an OBD reader and program? Something like those bluetooth/wifi units off of Amazon? If so get O2 sensor data. The O2 sensor voltage data can give you an idea of what the mixture is doing during driving. And most of these OBD programs have data logging which is helpful in situations like this.

I use a program called TORQUE on my Android tablet. Works great and even the free version does data logging.

I'd data log two parameters. Coolant Temps and O2 sensor data for both sensors and bounce the data off of each other. If it's running lean and causing overheating issues it could be injectors. Or it could be the Catalytic converter is starting to clog up and give you issues.

Either fix is pretty cheap. You can pick up Dodge Neon injectors off of Rock Auto for about 150 dollars, or a new Catalytic converter for about the same price or cheaper.

This is all assuming your cooling system is in top notch shape. And the fins in the radiator aren't clogged up causing an airflow problem.

If you ever replace that 3 row go back to a thick single core or 2 core radiator. Three row radiators in Jeep Cherokees don't have the best track record for cooling efficiency. I can run up a mountain at 70 mph with the AC on MAX using a fully stock cooling system and the OEM tow package radiator. Same for the fans. I've seen too many threads of guys with the 3 fan setup complain and do the cooling system rabbit chase (I'm guilty as well) finally get fed up and go back to all OEM cooling system (the rad is really important here most aftermarket "OEM replacement" rads are garbage you need the MOPAR unit) and magically all their overheating problems were fixed.

This unit will work with iDevices or Android. Android so far seems to have the better apps for this purpose.

Amazon.com : PWOW®ELM327 OBDII Car Auto Diagnostic Scanner Adapter Reader, WIFI Wireless ELM327 Diagnostic Scanner for iPhone4S/5/iPad4/iPad mini/PC in XP System, with Micro Disk : Car Electronics@@AMEPARAM@@http://ecx.images-amazon.com/images/I/51-iNGpIRjL.@@AMEPARAM@@51-iNGpIRjL

[Mayooo]

Do you have an OBD reader and program? Something like those bluetooth/wifi units off of Amazon? If so get O2 sensor data. The O2 sensor voltage data can give you an idea of what the mixture is doing during driving. And most of these OBD programs have data logging which is helpful in situations like this.

I use a program called TORQUE on my Android tablet. Works great and even the free version does data logging.

I'd data log two parameters. Coolant Temps and O2 sensor data for both sensors and bounce the data off of each other. If it's running lean and causing overheating issues it could be injectors. Or it could be the Catalytic converter is starting to clog up and give you issues.

Either fix is pretty cheap. You can pick up Dodge Neon injectors off of Rock Auto for about 150 dollars, or a new Catalytic converter for about the same price or cheaper.

This is all assuming your cooling system is in top notch shape. And the fins in the radiator aren't clogged up causing an airflow problem.

If you ever replace that 3 row go back to a thick single core or 2 core radiator. Three row radiators in Jeep Cherokees don't have the best track record for cooling efficiency. I can run up a mountain at 70 mph with the AC on MAX using a fully stock cooling system and the OEM tow package radiator. Same for the fans. I've seen too many threads of guys with the 3 fan setup complain and do the cooling system rabbit chase (I'm guilty as well) finally get fed up and go back to all OEM cooling system (the rad is really important here most aftermarket "OEM replacement" rads are garbage you need the MOPAR unit) and magically all their overheating problems were fixed.

This unit will work with iDevices or Android. Android so far seems to have the better apps for this purpose.

Amazon.com : PWOW®ELM327 OBDII Car Auto Diagnostic Scanner Adapter Reader, WIFI Wireless ELM327 Diagnostic Scanner for iPhone4S/5/iPad4/iPad mini/PC in XP System, with Micro Disk : Car Electronics (http://www.amazon.com/gp/product/B00MP6GSWQ?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00)

Yeah I have one for the car but the xj is a 94, can't use it.

[GoneWithTheWind]

Try and get a snap on scanner. I've seen some on e bay, but make sure you get the cartridges for the jeep and jeep trouble shooting.
http://i781.photobucket.com/albums/yy96/herein97217xj/DSC00529_zpssockjmfi.jpg (http://s781.photobucket.com/user/herein97217xj/media/DSC00529_zpssockjmfi.jpg.html) these are the cartridges you'll need.
http://i781.photobucket.com/albums/yy96/herein97217xj/DSC00530_zpsnze2hfmg.jpg (http://s781.photobucket.com/user/herein97217xj/media/DSC00530_zpsnze2hfmg.jpg.html) this is the adapter you'll need. It's a snap on diagnostics scanner MT2500.
I hope this helps.

[Mayooo]

Update... It seems my problem is limited to highway speeds. Saturday did a mild break-in run and on Sunday a few of us went out and wheeled some extreme trails.. Almost rolled twice. Both times coming home at 55+ mph the temps was creeping to the red. But while wheeling, even on Sunday's low range, high rpm's adventure the temps never went over 210.. ???

[OldFaurt]

Update... It seems my problem is limited to highway speeds. Saturday did a mild break-in run and on Sunday a few of us went out and wheeled some extreme trails.. Almost rolled twice. Both times coming home at 55+ mph the temps was creeping to the red. But while wheeling, even on Sunday's low range, high rpm's adventure the temps never went over 210.. ???

I have a 92... Replace your temp sensors, when they get old they drift like a Honda street race enthusiast!! Mine was all over the map... Now.. it's all cool.... well... Normal!

[Mayooo]

I came close to overheating again today. Not sure what caused it. Thought I got it worked out with the new o2 and cat. My driver side hub and rotor was smoking hot as well. Really don't think they go hand in hand. I've gone thru and checked and rechecked over everything..

I just don't know. When I'm wheelin it stays nice and cool.

[4.3LXJ]

Is the radiator core clean and allowing good air flow?

[slvmart]

I came close to overheating again today. Not sure what caused it. Thought I got it worked out with the new o2 and cat. My driver side hub and rotor was smoking hot as well. Really don't think they go hand in hand. I've gone thru and checked and rechecked over everything..

I just don't know. When I'm wheelin it stays nice and cool.

Actually, the 2 might be connected. The hub friction could be causing enough drag to make the engine work harder than normal. But I suspect your right foot should be able to feel that. As well as feeling it through the steering wheel.

[bluedragon436]

Hey, at least your overheat issue, seems highway speed related, and occurs quite a bit... Mine overheats randomly, whenever it feels like!! I drove mine down the highway, as well as down back roads, so higher speeds and semi slow speeds... and had no issues, but I've done slower speeds down back roads absolutely fine, then it randomly starts to stutter a little bit and creeps to what I'd say is "overheat" and shut off, and after it cools down a bit, it starts up and runs again, just fine... Almost wondering if it's not heat soak, that folks talk about, but seems odd that it hasn't done it other times that it heated up higher... So figure I'm going to replace everything in the cooling system, except the heater core (going to flush/back flush that though for hopefully getting heat back inside the Jeep before the winter comes).. and then I'll be doing my 99+IM, bored TB, 4 hole injectors and header.. and figure I'll see what I can do to protect against heat soak!!

[Mudderoy]

I came close to overheating again today. Not sure what caused it. Thought I got it worked out with the new o2 and cat. My driver side hub and rotor was smoking hot as well. Really don't think they go hand in hand. I've gone thru and checked and rechecked over everything..

I just don't know. When I'm wheelin it stays nice and cool.

Hmmm I wonder if you have a problem with driver's side brake which is more load on the engine to keep the vehicle moving. Maybe it's a combo.

[Mayooo]

Hmmm I wonder if you have a problem with driver's side brake which is more load on the engine to keep the vehicle moving. Maybe it's a combo.

I thought that too but the overheating started when I was taking my son to camp. That was about 2 weeks prior to the new hub and brakes. I was running the a/c up the mountain to camp when it overheated.. That is when it all started.
Both the front brakes where binding when they got changed and I believe the hub went to. I do have another new hub to try and also try to get the brakes sliding freely.