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Discussion Starter · #1 ·
New jeep owner here! Cluelessness is highly likely!

Recently bought an '01 Sport to replace the high-mileage '05 Ford Escape I've been driving. Had the vehicle for about a month or so now, and haven't had any issues until today. Was waiting in line at a drive-though and heard the Check Gauges alarm go off and saw that the temp gauge was at the left edge of the red mark. Attempted to exit the line but was boxed in by cars and brick walls (lifts only help so much), so I ended up creeping along by starting and stopping the engine. Did this about 3 times to get out of line, and by the time I was out my temp gauge was back to 'normal' with the needle in the middle of the 0. Drove home with my eye glued the the gauge, never had it go into the red again despite me never going faster than 20mph and hitting a bunch of stoplights/stop signs.

I thought it might have been a fluke in the gauge, so tonight I went and drove it around the block. Needle stayed around the middle of the 0, even with the A/C running. Parked it in the garage and revved the engine up to around 1500 for a minute to see if the issue was related to airflow. Didn't see any change until I was in the middle of turning the engine off and the gauge hit the lower red again. Toggled the switch a few times without turning the engine on and had the gauge read HOTTER and move from left of the red to the far right of the red. After a while it went back to the 210 range. Went to open the hood while waiting for the engine to cool and had to use a rag to keep myself from burning my hand on the hood.

I know something is wrong, but I can't tell if it's the gauge (why would the engine get hotter if it's not running?) or the cooling system itself (does the hood usually get that hot)?

So far I've checked:
Coolant: Green, and the overflow is filled up slightly past the full mark.
Oil: Pressure hovers around 40, clean oil, near full mark on the dipstick.
Fan: Fan has resistance when engine is hot. Doesn't spin more than 1 revolution.
Airflow: Radiator looks clean, no issues on the highway. Fan moves fast and moves quite a bit of air.

Any suggestions? I find it odd that this issue has only crept up now, as I've done a lot of idling that should have caused a cooling issue to rear it's head earlier. The only other thing that could possibly be related to this is that the Jeep has a slight high-pitched whine at certain speeds/loading. Sounds like the type of whine you get from a bearing, but not sure. I have a 90-day Nationwide warranty from the dealership I bought it from, so if this is a cooling system issue I'd like to find out what it is and if I need to start heckling people.
 

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I have a 90-day Nationwide warranty from the dealership I bought it from, so if this is a cooling system issue I'd like to find out what it is and if I need to start heckling people.
More than likely one of two things either the fan clutch is bad or the thermostat is sticking intermittently. Would lean more towards the fan clutch myself.

Take it back to the dealer and use that 90 day warranty you paid for.

Let them figure it out.

(why would the engine get hotter if it's not running?)
Very common in any vehicle as there's no coolant flow
 
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Discussion Starter · #3 ·
Take it back to the dealer and use that 90 day warranty you paid for.
Called the dealer, turns out the warranty has a $100 deductible (yay....). Seeing how most of the parts are less than that, I'd rather fix it myself and learn a bit in the process.

You mentioned that the issue could be the fan clutch. How would I determine that? I can see the fan stop when the engine stops turning, so I know the fan is engaged and isn't free-wheeling.

I'll see about letting it idle without the tStat this weekend. Should let me know if that's the issue.
 

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Donny man, I get you. The same thing is happening to my Jeep and I'm going nuts. I have a '97 Sahara and it only overheats at idle. It also happened to me at a drive thru. Mind you, I live in Miami and there's a shit ton of traffic and it's always beating hot out......doesn't help the situation.

I'm still trying to figure it out. I bought it from a guy across the street from me, so I don't have the advantage of bringing it to a dealership, but my aunt is a Jeep mechanic so we're trying to figure it out. Mudbug85603 mentioned something that my aunt and I are almost 100% is the problem:

Fan clutch
Thermostat
Bad water pump

I highly doubt it's the water pump, but it's worth giving it a look.

Let me know what they tell you or what the solution is. I'm trying to figure it out to hahahaha. I hope everything works out okay for you, Donny.
 

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Discussion Starter · #5 ·
Heh. The funny thing is, I've been in longer drive-through lines before. Maybe my Jeep thinks I should have gotten burgers rather than chicken?

So far I haven't gotten hot enough to throw a CG light, but I've been spending more time staring at the temp gauge than the spedometer. You have my sympathy for Miami. North Texas is hot as the dickens, but it's not nearly as humid as there or Houston. I sweat a bit without AC, but at least I dry out when I start moving again!

Got a chance to take the Jeep to a local mechanic the other day. They said that it was getting hot at idle, but if they revved the engine it cooled down. Not sure if that's a dirty radiator or a clogged radiator. Looks clean from the outside and from what I can see inside the cap.

I can confirm I get better cooling with the engine running faster. Was running over the 210 dot today and cruised in 1st for a while and had the temp drop back down below the dot to about 195. I guess forcing more air across the radiator compensates for whatever is causing the overheat? I'll have time and tools to look at it Saturday and will report back then.
 

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A hood hot enough to be hard to hang onto is perfectly normal. After all it has a big heater sitting directly underneath.

Your overheating could be nothing but a sticking thermostat. They usually cause sudden rather than slow temperature changes. I'd replace it with a new 195 degree non-failsafe thermostat like a Stant. A Stant SuperStat would be a great choice. Avoid any thermostat that claims to be "fail safe". That sounds good but it's not as they just tend to fail in the open position.

Avoid the temptation to install a lower temperature thermostat like a 165 or 180 degree model. The computer is programmed around the specified 195 degree model.

Finally, if you replace the thermostat, use a standard paper gasket and not RTV. Make sure you get ALL of the old gasket material off (a small fine wire brush helps) or it will leak.

No guarantee your overheating is caused by a sticking thermostat but that'd be where I'd start. Not to mention a thermostat is the cheapest component in the cooling system that could cause your symptom. .

Good luck with it.
 

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I had a very similar problem, the gauge would pin to the hot.. I would freak out pull over let her cool down, and all would be normal, then at random the gauge would pin, eventually the jeep started having issues where it would not start after a short drive to the store or it would start but run very rough, turned out it was the temperature sending unit, It was making the gauge act wacky and putting the jeep into a "limp" mode, (it does not throw a code) It is a cheap fix about 20 bucks at advance before coupons and is easier to change than a spark plug, might be a good place to start and see if that helps
 

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+1 for fan clutch/thermostat. The fan clutches are known to be issues, and the thermostat sticking will cause similar issues. I used to have problems similar to yours, replaced the thermostat, fan clutch, belt (cause I was there) and the water pump (for piece of mind) Where the temps used to be 215 (as monitored via OBD port - the gauges are hugely inaccurate) and would get up to 235/240 sitting in a drivethrough - temps after the change are closer to 200-205 operating, may get up to 215 in a drive through line now. Revving the engine does help as well - need to figure out a high idle switch like the police package XJ.
 

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Discussion Starter · #9 ·
Well, spent the weekend learning the importance of being sure ALL the paper gasket is removed when you replace a thermostat. Thought I had it all off the block until I started adding coolant and heard it falling on the ground. A bit of chemicals and a second trip to the auto parts store later and I now have something that will hold up for longer than 5 minutes.

Engine still seems to run hot, however I haven't tested it idling for fear of overheating again. Got an OBD2 reader capable of reading live data on the way, so once that comes in I'll be able to be more sure about temps than "the temp gauge seems a little too far to the right of the dot".

By the way, has anyone experienced their coolant being a reddish color when drained? Prior to breaking the system to install the tStat I had green coolant in there, but the coolant I drained into the bucket had a reddish hue when the radiator was all emptied. From what I saw the coolant coming out of the drain was green, but I didn't see the initial coolant release so I may have missed something. Ran my finger in the bottom of the radiator where the lower hose connects after draining and didn't feel any silt down there. Maybe I didn't wash out the bucket well enough?
 

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Discussion Starter · #10 ·
Okay. Just got in my OBD2 sensor and can confirm the TStat didn't help. Parked in the shade and turned on the A/C and watched as the temp slowly tried to climb it's way past 230. Like before, a quick jaunt in first for a few minutes cooled her down right quick.

A few people mentioned the fan clutch. Is there a way to test if mine is bad before I go and possibly replace a good part? Fan spins with the engine, and doesn't feel loose when I turn it off.
 

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Discussion Starter · #12 ·
Finally got a new fan clutch in. Spent a week trying to get the old one off. Water pump pulley kept slipping on the belt when I went to turn the wrench on the clutch bolt. Ended up loosening three of the bolts on the pump pulley and using them as stops for a second wrench. Came off after that!

All that work seems to be for naught, as I'm still climbing above 220 idle even with AC off. :banghead:

Before I pull the pump or do something else that requires draining the radiator (again), is there a proper way to inspect tension on the serpentine belt? I find it odd that I had the pulley slip while I was trying to get the wrench off, as it didn't take too much force when I got the bracer in there. Can a slippery belt lead to the fan not turning fast enough when idle? Or am I just hoping for a "free fix"?
 

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Could be your radiator is simply clogged up from either hard water deposits (lime or calcium) or gunk from it not having been flushed properly by the previous owner. Drain the coolant down enough so you can look down into the radiator cap opening and see if you see a bunch of white deposits built up around the channels. If you can, it's likely clogged with them. Those deposits are caused by having used tap water instead of distilled water to mix with the coolant.

If you decide to replace it, keep in mind that most store-brand radiators are cheap junk that will either fail prematurely or, more commonly, not cool as well as the OE radiator design does. And also know that more 'rows' in a radiator doesn't necessarily mean better cooling. Jeep went from a 2-row aluminum core design to a better designed 1-row aluminum core design in around 2000 and achieved better cooling characteristics.
 

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Could be your radiator is simply clogged up from either hard water deposits (lime or calcium) or gunk from it not having been flushed properly by the previous owner.
I had to put a radiator in my wife's Durango last weekend. My mechanic used a heat sensor of some sort, and could tell that the old radiator was significantly hotter on one side than the other, showing how bad it was plugged.
 

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I'll give my experience with a warm running engine on my TJ. Engine would run 220 to 235 with AC on pulling I-80 grades in the lower Sierras with 100* ambient temps. Without AC on temps would be 210 to 220. I thought my fan clutch was bad because I never heard it engage, even at high temps. The fan spin test would pass. I replaced the fan clutch anyways as the temps wouldn't spike, but gradually rose. A couple weeks ago I decided to replace the radiator(Mopar), t-stat (Stant Super Stat), and all hoses as the Jeep is 14 years old now. After removing everything except the water pump(which I didn't think was the problem), I flushed the block and heater core, and using compressed air I tried to remove as much of the tap water as possible from them. I installed everything, filled with Zerex G-05 50/50 coolant and went through the process of starting and burping the system. What I have now is a cool running Jeep that doesn't go over 207-209 with the AC on driving the same area or sitting idling. What surprised me though was now when I sit at a stoplight, and upon taking off again the fan clutch is engaged for 10 - 15 seconds. This never happened before the radiator replacement. Obviously the radiator was not transferring heat as it should and the fan clutch didn't receive the heated air required to engage for better cooling. My old radiator looked good for as old as it was, and I didn't expect it to be the problem. It is so nice now to have my Jeep running cool and not worrying about the temps all the time.

Rich
 

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Discussion Starter · #16 ·
Turns out I need to be more careful in the engine compartment, and check my work I do closer. Went to take the Jeep to the shop to have them test the radiator and (hopefully) get a new one under the warranty I have a few days left on. They ended up finding that the top hose was a bit loose and had a small leak. Must've knocked it loose when I was in there trying to get the fan clutch off and didn't notice it, cause it sure as heck didn't leak when I replaced the T-Stat.

Shop tested the radiator pressure and said it was fine. Then then let it sit idle for 5 minutes and it stayed right at 210-213. Took it home and let it idle for longer and it very slowly creeped up to 217, but didn't really want to go higher. Drive through topped out at 214. Are these reasonable temps? It's cooled down about 5 degrees due to hurricane Harvey, 85-90 highs. Still a solid 208-210 when not idling.

Either way, the new (Hayden) fan clutch definitely seems to be making a difference now that I don't have a leaky hose. When I overheated I tested the Jeep in idle when it was about 90ish. Back then I got a Check Gauges light. Now I can't even crack 220. The clutch that was in there was a cheap AutoZone unit built in 2015. Not sure if I like the implications of that with respect to cooling system maintenance of the PO....

Oh, and to answer your question, Jerry: No, there weren't any obvious signs of corrosion or buildups in the rad. Took a good look at that when I had it drained to replace the T-Stat. If I'm shopping for a new rad, is it sufficient to get one with OEM specs, or is it Mopar or new rad in 3 years?
 

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Cheap store brand radiators claim OEM specs or to be OEM replacements. Best to be very picky about the radiator you install, and know that more rows seldom mean better cooling. I like a lot of aftermarket parts like Stant thermostats and Bosch fuel pumps but if it was a radiator for my TJ it'd be a single row aluminum core Mopar.

Lastly... going back to the OE constant tension hose clamps the factory installed would mean you'd never have worry about getting them tight enough again. Not to mention the OE constant tension hose clamps always provide the correct tightness no matter what the temperatures are. Those worm drive hose clamps sold by the auto parts stores are, generally speaking, inferior for radiator hoses and a downgrade.
 
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