Over-heated, but not low on coolant

[Jim McClain]

When I drove up Mt. Hough the other day, the temp gauge indicated my KJ (2005 Limited) was very nearly pegged hot. I opened the hood and the coolant was bubbling. It cooled off while my friend and I shot photos and it didn't over-heat on the ride back down the mountain. I got some G-05 rated coolant to top it off when it was cold, but the fluid level seemed to be where it's s'posed to be already.

It was kinda hard to see the level because, 1, I'm not familiar with this vehicle yet and, 2, the coolant reservoir seems to be discolored for some reason (but that could be because of 1).

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The previous owner maintained this vehicle regularly, but I don't have anything that says coolant flush. I'm wondering if that is something that is a good idea at 105,000 miles. I s'pose there are a lot of things that should be done with this mileage, but I have a limited budget, so need to schedule things one at a time.

I haven't noticed over-heating before, but that's not to say it didn't happen and I just didn't notice. It isn't hard to mistake that bubbling sound though, so this was prob'ly the first time for me.

The tank seems to have 2 chambers. I can't see any fluid in the right side chamber. The left side fluid level isn't actually level - it's higher on each side than in the middle (you can see that in the pics).

Any experienced advice would be appreciated.

Thanks,

Jim

 

[LibertyTC]

Jim do not let the jeep get pegged, if I saw 3/4 + is too hot, then shut er down & then open hood for a while!
Suction out some of the coolant in reservoir and inspect for particle or even oil.
Consider a pressure test for leaks.
Add to reservoir only when cold to cold line.
If it is overheating like described many conditions can cause it.
A new water pump may be recommended with new thermostat 195 Mopar, and flush ya, well over due if it has not been done. A good time to do Upper & lower rad hoses too.
I let the dealer do my coolant flush, not overly expensive, but they have the right recirculating machine and distilled water mix already. No hassles, no dealing with recycling hoat coolant.

 

[TwoBobsKJ]

I agree with Tim. The dealership charges a reasonable fee (comparable to any local shop) and they do a true system flush.

Based on your pics, Jim, there's plenty of fluid in the reservoir. The center mold line is the "Cold Full" line and the 'tab' above that is the "Hot Full" line. Don't know how hot your Jeep was when the pics were taken but the level is actually above the "Hot Full" line.

I also wonder if the water pump is going bad... If a previous owner used anything but HOAT the impeller blades on the pump may have 'melted' due to an incorrect coolant. That's one of the reasons Chrysler specifies HOAT (GO5 is also my preferred coolant.)

These engines like to remain cool - next time up the mountain keep your eye on the temp.

Bob

 

[LibertyTC]

One thing we forgot to mention when it was hot doh. or ask was...
Was the fan spinning at high speed ? Do you just have the electric fan or HD clutch cooling as well?
Oh & if the reservoir is kinda nasty, it does not take much to remove it & give it a good cleaning or even get a new reservoir...I wonder how much a new reservoir is..??
They tend to get discolored easily from the hoat brownish stuff, likes to stick inside.

 

[Jim McClain]

I agree with Tim. The dealership charges a reasonable fee (comparable to any local shop) and they do a true system flush.

I understand that. I wouldn't try to do that kind of work myself.

Don't know how hot your Jeep was when the pics were taken but the level is actually above the "Hot Full" line.

I saw that. It wasn't cold, but it was nowhere even near hot when the photo was taken.

I also wonder if the water pump is going bad...

Good question. Is there a simple way to determine? Water pumps aren't terribly expensive, but RockAuto lists several. Is there a known better quality pump?

These engines like to remain cool - next time up the mountain keep your eye on the temp.

Of course. All my normal driving, so far, has the needle directly in the middle of the dial. Is that where it should be? I have no idea what thermostat's in it. I s'pose I should change that too.

One thing we forgot to mention when it was hot doh. or ask was...
Was the fan spinning at high speed ? Do you just have the electric fan or HD clutch cooling as well?

Don't know. I think nothing was spinning after I shut the Jeep down - don't know if, like some cars, the fan's supposed to continue to spin until the engine gets to a certain temp. 'Fraid I don't know what a "HD clutch" is. I just assume the fan was working during the ride up, but maybe it wasn't. :think:

Oh & if the reservoir is kinda nasty, it does not take much to remove it & give it a good cleaning or even get a new reservoir...I wonder how much a new reservoir is..??

$48.62 and free shipping on Amazon. I will probably get that, the water pump and a thermostat and then take it to the shop for a flush and parts replacement. I'm guessing, at the least, that would be good preventative maintenance. The hoses look in very good shape.

Appreciate all the help,

Jim

 

[tjkj2002]

Don't rely on that temp gauge as being correct,it's a dummy gauge.


At the halfway mark the coolant is between 178 degrees and 229 degrees,at 3/4 mark it's between 230 degrees and 259 degrees,and at full hot mark the engine is 260+ degrees.


The main electric cooling fan should come on at 219 degrees(+/- 2-3 degrees).With HD cooling the OE fan clutch fully locks at 230 degrees.


The OE t-stat(and only one you should be using,IE dealer only) is 195 degree t-stat,starts to open at 195 degrees and fully opens at 218 degrees.Located engine side of lower radiator hose,cone facing towards radiator and spring side facing engine.


As far as waterpumps MOPAR is best but good aftermarket options are Napa's "new" trueflow or Cardone's "new" WP with metal impeller.

 

[LibertyTC]

Jim the electric fan should be running at high speed automatically when A/C is on for instance.
The fan should also run when the engine is hot, so that is something to definitely look for when Jeep is running. You should inspect the fan to know if it is working & running properly.
When ignition is off, the fan is off.
The dash gauge is approximate, I have an Autel ****-trip TP-100 reader plugged into the OBD2 port, which will report the computers coolant temp sensor, which is way more accurate and stays working in the Jeep at all times.
Turns off check engine light, reads codes & tons more.You can see in this photo it reading 215 Fahrenheit,water temperature.
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There are numerous readers out there, just helping you to spend more cash or add to a wish list:icon_lol:

Avondale wholesale lists the OEM jeep coolant reservoir at $48.96 shipping included.

 

[boboborino]

My money is on the fan and relay.

Bert

 

[ltd02]

My money is on the fan and relay.

Bert

I'd check that first too. Then water pump. However, when my fan relay went I got a P1491. If just the fan quit there would likely be no code.

 

[M38 Bob]

Probably redundant, but first I'd check for restrictions in air flow. Dirt, bugs, deformed radiator fins, etc.

Bob


Sent from my iPad using Tapatalk

 

[Jim McClain]

UPDATE on engine heat problem

Turns out the problem is a broken fan clutch. My shop has to order the part, which means the fix is delayed until Friday.

I looked on RockAuto and there is a Hayden 2736 Reverse Rotation Heavy Duty Thermal Fan Clutch. My shop wants to use a CarQuest fan clutch. Is anyone here knowledgeable about such things? The CarQuest part is private labeled, so I don't know if it's a quality part or just some cheap crap made in China to optimize CarQuest and my shop's profit margins. For all I know, the Hayden part is made in China. :shrug:

This is the problem with small town rural shops. I rarely shop the local CarQuest because their prices are generally higher than Napa for the same or lower quality.

Jim

 

[HoosierJeeper]

I would personally get the Hayden but Carquest should usually be in line with Napa quality wise I think. But you'd probably be ok with Carquest.

 

[TwoBobsKJ]

When I needed the fan clutch I purchased the Hayden at Summit Racing - a place not known for their low prices - and it was around $55. Personally I'd buy the Hayden just cuz I've used them in the past and they worked well. Plus I went there because nobody else had one in stock and Summit is only 15 minutes up the road. And I always like looking at the incredible muscle cars they have in there loaned by local gear heads. They had a '70 Super Bird Hemi in there last time I swung by - lady had to give me a bucket to catch the druel dripping from my mouth :happy175:

I tend to get impatient when I make up my mind to do a mod or repair. Gotta have it now :mexsmoke:

Bob

 

[Jbergun]

I am the same way when i want/need something done to my jeep i want it now like its life or death. Its a blessing and a curse. I am worried about your cooling level jim. In the first picture you posted the tank is full to the top . That is not an ideal level hot or cold.

 

[Jim McClain]

I am worried about your cooling level jim. In the first picture you posted the tank is full to the top . That is not an ideal level hot or cold.

I took note of that from previous replies and I used a turkey baster to pull some of that out to the cold line. I'm gonna schedule a coolant flush and replace all the fluid.

Thanks.

 

[uss2defiant]

Napa clutch fan is also recommend here in the forum.
Lifetime warranty as well
NAPA AUTO PARTS

 

[tjkj2002]

Turns out the problem is a broken fan clutch. My shop has to order the part, which means the fix is delayed until Friday.

I looked on RockAuto and there is a Hayden 2736 Reverse Rotation Heavy Duty Thermal Fan Clutch. My shop wants to use a CarQuest fan clutch. Is anyone here knowledgeable about such things? The CarQuest part is private labeled, so I don't know if it's a quality part or just some cheap crap made in China to optimize CarQuest and my shop's profit margins. For all I know, the Hayden part is made in China. :shrug:

This is the problem with small town rural shops. I rarely shop the local CarQuest because their prices are generally higher than Napa for the same or lower quality.

Jim

A broken fan clutch on a HD cooling system installed on a KJ will not cause it to overheat unless your towing 5000lbs up a 12,000' pass.


The electric cooling fan on any gas KJ is the primary cooling fan and those with HD cooling the added mechanical fan is just for added airflow at extreme use like max towing up long grades.You can totally remove the mechanical fan and you should never overheat if the ecletric cooling fan and cooling system are functioning correctly.




The OE clutch doesn't even fully lock till 230 degrees,11 degrees after the electric cooling fan turns on.

 

[Jim McClain]

A broken fan clutch on a HD cooling system installed on a KJ will not cause it to overheat unless your towing 5000lbs up a 12,000' pass.

The electric cooling fan on any gas KJ is the primary cooling fan and those with HD cooling the added mechanical fan is just for added airflow at extreme use like max towing up long grades.You can totally remove the mechanical fan and you should never overheat if the ecletric cooling fan and cooling system are functioning correctly.

The OE clutch doesn't even fully lock till 230 degrees,11 degrees after the electric cooling fan turns on.

I just started the engine and both the mechanical and electric fans run. I turned off the AC and both fans continue to run. Of course, when I shut the engine off, both fans stop spinning.

If the mechanical or electrical fan is only supposed to run when the engine reaches a specific temperature, then something is amiss. My Jeep has not been operated all night and morning. There's no way it could be even slightly warm to the touch, let alone be at a temp that triggers the operation of a fan, unless that trigger point is about 80° F.

Jim

 

[tjkj2002]

I just started the engine and both the mechanical and electric fans run. I turned off the AC and both fans continue to run. Of course, when I shut the engine off, both fans stop spinning.

If the mechanical or electrical fan is only supposed to run when the engine reaches a specific temperature, then something is amiss. My Jeep has not been operated all night and morning. There's no way it could be even slightly warm to the touch, let alone be at a temp that triggers the operation of a fan, unless that trigger point is about 80° F.

Jim

The mechanical fan will always spin when the engine is running.The electric cooling fan will run when the engine temp reaches 219 degrees or a selection on the HVAC that uses the AC is selected like defrost and on newer models floor vents along with any AC mode.

 

[Jim McClain]

The electric cooling fan will run when... a selection on the HVAC that uses the AC is selected like defrost and on newer models floor vents along with any AC mode.

I turned the HVAC off. The electric fan continued to run. :shrug: