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Temp running 220 with A/C on

Ken G Ford

Member
Joined
Apr 29, 2021
Messages
54
Location
Gilbert, AZ
1997 Jeep Wrangler Sport automatic with 82,000 miles.

So, volunteered to stand flags at national cemetary on memorial day and while waiting, my jeep overheated. Easy to do here in Phoenix at 115deg.
identified a cracked radiator along top of plastic one inch long. Threw job JB Weld along carck to get me home, refilled with water and nursed it back home but on the highway about 10 miles from home, I over heated and had a hard time pulling over with all the traffic and ended up blowing head gasket. Confirmed when I got it home by looking at wet plugs.

Pulled the head and had a machine shop clean it, magnafluxed, new valve stems installed, three angle valve job, machined the head in case it was warped, etc.

Since I had it all apart I decided it was a good time to throw in a long tube header, Banks Monster Cat back and 62mm TB and Air Filter, new Spark Plugs, 4 hole injectors, new silicone radiator hoses along with silicone heater hoses.

Also decided to upgrade the radiator with a three core aluminum one and a temp switch controlled electric fan..... needless to say, wasn't happy with electric Fan
as it just didn't push enough air and it over heated again. Luckily, this time I was able to pull over to the side of the road at around 225 deg. I also added a digital
Temp Gauge plumbed into the top heater hose since I just didn't trust the stock gauge. Let it cool down and after getting back home.....decided this three core
aluminum radiator with weak electric fan was BS. After all, never had temp issues with the stock radiator and Stock fan.

Put a stock radiator and stock fan back in..... can feel hot air blowing down at my feet when standing in front of the jeep at idle. With the electric fan I was only able to hear it running and had to put my hand near the fan to know that it was running. Definitely have much more air flow through OEM Single Core radiator and stock fan then the electric fan with aluminum 3 core radiator but.....still running high Temp at around 224 or so with AC on.

Keep in mind this thing has rebuilt head, Water Pump is a year old, thermostat a year old, Heater core flushed last year, new single core OEM Radiator, New Silicone hoses, spark plug, 4 hole injectors, etc.....

I actually never disconnected the battery so am doing so now in case the computer is having issues relearning with all new TB and INjectors, Exhause. Maybe running lean? that and I might go back to stock rubber radiator hose on the bottom in case this siicone one is getting to hot and colapsing? obviously I can monitor it while driving but I do know some cars came with a spring inside the lower rubber hose to keep it from collapsing....

Any other ideas I should look for ?
 
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Ken G Ford

Ken G Ford

Member
Joined
Apr 29, 2021
Messages
54
Location
Gilbert, AZ
Interesting update. Since the 62mm TB was added after blowing head gasket and re-installing the machined head, i decided it was easy enough to remove 62mm TB and replace with OEM TB.......

Jeep runs and accelerates better with stock TB then the 62mm TB...... weird.

Runs so much better that the stock TB is staying on and Im gonna sell the 62mm TB. It pulls much harder from a stop and shifts better with OEM TB. Not sure if the 62mm was causing the jeep to run lean ?

Anyway, the temp was 96 deg this evening and I went for a test drive after changing back to the OEM TB and disconnecting the + side of battery for awhile to clear the computer. driving for 8 to 10 min my dash temp gauge showed needle between the 1 and the 0 of 210.
My digital gauge was showing 222 deg. Seems like when I maintained 55MPH to 60 MPH steady temp would climb to where the needle was to the far right of the 0 of 210 and the digital climbed as high as 230 at one point. Then when I came to a stop light, the temp would drop back down to 217 to 219 ...... the jeep consistently runs cooler sitting at idle rather then at 55mph. At no time did the red "Check Gauges" pop up on the dash nor did I see any boiling in the over flow tank. Both happened with the 3 core aluminum radiator and electric fan previously.
Anyway, plan to take a test drive again tomorrow with the sun out and around 115 deg to see what the Jeep does temp wise..... wondering if the digital gauge is causing me more concern since it is obviously more accurate v.s. the needle hovering somewhere above 210..... To be honest, Im not even sure at what temperature the "Check Gauges" lights comes on to be honest.
 
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Ken G Ford

Ken G Ford

Member
Joined
Apr 29, 2021
Messages
54
Location
Gilbert, AZ
OK, interesting observation. I went ahead and replaced the Fan Clutch although it felt fine....I was at a loss and it was only $52.00....
well....the temperature seemed more stable at 217 both on a morning test drive at 95deg and later in teh afternoon at 103deg..... mainly stayed at 217 to 219. Got on the freeway and at 74MPH temp climbed as high as 221.... pulled off the freeway and at 1st light it climbed to 223 to 223 and then all surface roads back home was at 219 mostly and couple of times dropped to 217. Well....decided to experiment and popped off the grill slot plastic covers. I have the ones with round holes and figured it would help protect AC condensor while wheeling.
Well what a suprise, made the same test drive on same surface streets and the temp dropped down to a steady 217 to 215.....

In summary I do think I had an issue with Fan Clutch as the old one had oil stains in the front along with dust that had attached itself to the oil. Just hard to test by hand...cold or hot.

I can also confirm that the plastic grill covers probably adds 2 deg or so due to the restriction.

Keep in mind I live in Phoenix and its been 103 or so over the last couple of days. Its also common to see 115 to 118 in Aug.....

Keep in mind water boils at 212 deg but under pressure of a 16 PSI or so....probably boils around 255 to 260. Digital Temp gauge has never gotten anywhere near that high and obviously the stock one only reads to 210. Mine sits one needle with past 210 at this time.

I also think that the digital Temp Gauge is gonna drive me crazy!! I find myself staring at it the whole time I'm driving and stressing that I see it climb deg by deg to a whopping 220..... LOL

Seeing as I can seem to leave anything alone.....I may get a louvered hood to help lower the engine compartment temp and hopefully get let the radiator work and last a little longer. Maybe a high flow cat to help hot exhaust escape a little faster as well.

So, I think the Temp Issue has been resolved :)
 
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KingCarGuyZ

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Feb 26, 2020
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1,230
Location
Dallas, TX
Seems like when I maintained 55MPH to 60 MPH steady temp would climb to where the needle was to the far right of the 0 of 210 and the digital climbed as high as 230 at one point. Then when I came to a stop light, the temp would drop back down to 217 to 219 ...... the jeep consistently runs cooler sitting at idle rather then at 55mph. At no time did the red "Check Gauges" pop up on the dash nor did I see any boiling in the over flow tank. Both happened with the 3 core aluminum radiator and electric fan previously.
I think you are finding out the hard way what a lot of us already know. The factory cooling system on the TJ's is hard to beat. They do like to run hotter than most, but they were engineered for it. Normally I would recommend an additional electric pusher fan in front of the Rad. to help with idle temps, but it seems like you are having more of a problem when you run down the road than at idle. I know it sounds stupid, but I would check to make sure your fan is oriented to pull air through the rad and not push it out the front of the Jeep, as well as check for coolant flow restrictions and make sure you are using the proper HOAT coolant. I do like the idea of possibly running lean, would explain some of the heat build up under load, I don't think the exhaust should have much to do with it. did you use the same lb injectors? - I wonder if they could be contributing to an out of spec mixture, but your O2 sensor and computer should correct that to a decent extent.

Best of luck, the digital gauges can drive you crazy. I have an ultra-gauge and have it set up to alarm at 220*, so I have been able to largely ignore it until it yells at me (well before the stock gauge does)
 

cpwolf

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Joined
Jun 15, 2020
Messages
883
Location
Cedar Park, TX
You installed a separate digital gauge on the top hose, but have you looked at one that is on the OBD port? Curious about the comparison, you would see if the hose digital is reading the same as the TJ Computer.
I have a trail dash and 215 to 220 is far too common and even higher. I’ve got a new mopar radiator coming and just flushed the entire thing and put in a stant with the hole drilled (my 2 year old didn’t have the hose. And I bypassed the Heater core I suspect a small leak.

I’m in Cedar Park, TX outside Austin, and if this radiator doesn’t do it, I just don’t get how these guys are getting 205 supposedly on 110 degree Colorado day or whatever. Everything will be stock, and I’m interested in seeing the results.
 

CharlesHS

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Mar 10, 2020
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As for the engine running LEAN; you should be able to check that with the trim specs on fuel injectors loading.
Do you have a crack or leak in the exhaust header/manifold ?
My 1998 XJ 4.0L had a crack in the exhaust header where the tubes joined causing an exhaust leak (audible ticking under load) which created a lean condition as the exhaust leak became worse.
Check the condition of the exhaust PRE catalytic converters (ball in exhaust); IF they are partially obstructed the exhaust pressure will build up causing a drop in power, the engine needing to work harder at highway speeds causing the engine to run warmer.
 

IOwnCalculus

Member
Joined
Oct 31, 2019
Messages
96
Location
AZ
So I did a little monitoring myself just now - started off already hot, and according to Weather Underground the temperature along my route was somewhere between 101 and 106 with a wet bulb of about 62 degrees. Drive was on surface roads peaking around 50-55MPH.

With the air conditioner cranked, it seems like engine coolant temperature has more to do with fan speed than anything else - and fan speed is more dependent on lack of airflow than anything else. Sitting still and idling mine would climb to 220, and I even saw 224 while in steady-state 50MPH driving. But, if I stopped at a light for a while, sometimes it would be long enough for the fan clutch to get hot and lock up. Once the fan clutch locks up, it pulls a lot of air, enough that with the clutch locked up I saw temps drop as low as 208 at speed.

Personally I'm not sure how (or if to even bother) interpreting this data any further. I suspect that the winch and power steering cooler I have are reducing airflow enough that even at speed, the engine fan is beneficial... to a limited extent. Even at 224, the engine is running fine, the engine oil isn't getting too thin to lose pressure, and the air conditioning is cold. Still nearly 40 degrees below the point where the dash starts chiming at you for overheating.
 
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Ken G Ford

Ken G Ford

Member
Joined
Apr 29, 2021
Messages
54
Location
Gilbert, AZ
Hello everyone.

Wanted to update the latest heating issue on my 1997 TJ with 78700 Miles and automatic transmission.
So, after getting the engine back together the engine developed a tick/slap knock upon startup. Usually very loud in the morning and then 10 minutes into driving, it would quite down. Started doing some research and determined the noise could be Lifters. So, after sitting over night I pulled the valve cover and attempted to move rocker to see if any had some space between rocker arms and push rod tubes. All rocker were tight as a drum so made the determination that what I was hearing was not old lifters bleeding down.

Then I hear about the flex plate bolts coming loose of some of the early TJ's and as the engine turned, caused a clicking noise. Pulled the access cover between the engine and flywheel and checked all bolts after rotating the engine. No issues found.

Then read about the dreaded Piston skirt cracking issues on early TJ's and started think about pulling oil pan.... After doing alot of soul searching and recalling the fact that I take this TJ way out to the desert in 100+ degree temperatures..... I found a good engine builder in Glendale AZ and pulled the trigger for a full re-build. Figured, even if I found pieces of piston skirt in my oil pan, I was really able to address it myself anyway. Sure enough when they pulled the motor they were able to determine scoring on the three of the cylinder walls and badly damaged piston skirts which caused piston slap. A huge surprise for me as up unto this point, I really babied this jeep with constant oil changes, filters, tune ups, etc.....I plan to drive this jeep as long as I am able to climb up into it :)

So, engine was pulled apart, cleaned,hot tanked, magna fluxed and crank turned 10/10 and cylinders bored 30 over. ALL new parts installed to include Oil Pump, Water Pump, Head completely rebuilt with new valves, springs, bushings and valves machined with three angle valve job.......again.
All new timing chain, gears, pistons, rings , lifters , etc..... what you would call a zero mile engine.

So I get the jeep back from the shop and the idle is spot on. Acceleration is buttery smooth.Doesnt feel like any more power then before but happy that the noise is gone. However, I watched the digital temp gauge I installed while driving home which climbed to 210 on surface streets but shortly after climbed as high as 230 on the highway.

Drove it to work the next couple of days and the temp climbed as high as 228 on the commute to work and back which consisted of surface streets.

Decided to make sure it was burped correctly and I drained 70% of the Antifreeze and added Red Line Water Wetter along with distilled water to top it off. Had good results in earlier testing so wanted to see if it would help again.

Well, today on the third day of driving it to work, I ran an errand on the way home. Mixed surface and highway driving......ending up having a REAL scare when the digital temperature climbed as high as 242. Pulled into COSTCO and let her cool off for an hour and then climbed back in to drive the rest of the way home using only surface streets...... Temperature climbed to between 226 and 228 for the majority of the way home but eventually climbed to 233 and as high as 237 when I pulled into the driveway.Once it was idling, it dropped to 228.

Keep in mind this is AZ and the temp outside was 109 deg. None the less I am now TERRIFIED to drive the thing which poses a problem since she is my daily driver.

In summary, new radiator, new Fan Clutch, fresh professionally built engine with new Oil Pump, Water Pump, etc....

Any ideas from anyone on here??????

ALMOST tempted to go back to a oversized 3row aluminum radiotor but just not convinced it can cool better then OEM Single Row.
 
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Ken G Ford

Ken G Ford

Member
Joined
Apr 29, 2021
Messages
54
Location
Gilbert, AZ
What is everyone's thoughts on Old Catalytic converter?

Didn't look plugged at all when I had it off but it is 25 years old after all..... Also, no CEL what so ever.
 

CharlesHS

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Mar 10, 2020
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I would suggest replacing the radiator with the stock Mopar OEM; it has been proven to cool the best.
None of the alternatives have proven to have to cooling performance and longevity of the Mopar.
The CC could have a problem; you will need to have a temperature and pressure drop performed by a exhaust shop unless you have the tools to perform these tests.
 

Sensei

TJ Enthusiast
Joined
Aug 23, 2022
Messages
111
Location
Kansas City
Thanks @CharlesHS.

I agree that OEM radiator would be best option but also wondering if it would lower temperatures by 30deg ?
Did you ever resolve these issues? My jeep is starting to run hot as well. First had issues on very hot days with ac on, so I stopped running ac. Then I started having trouble at higher highway speeds. The worst was when I came directly off the highway into a drive-thru, and was idling there for 10 minutes. During that time (turned ac on while waiting), temp gauge maxed out and Check Gauges light came on. Turning off ac seems to help in general, but not anymore. The cooling system has become marginal I believe. But my symptoms are near identical to yours so Im wondering if you've found a resolution?
 
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Ken G Ford

Ken G Ford

Member
Joined
Apr 29, 2021
Messages
54
Location
Gilbert, AZ
In the end I went with a premium aluminum 1 Row radiator from Rock Auto.

Hasnt gone over 215 deg and that idleing in 105 deg weather for 10 min at a Watta Burger drive through. As soon as I puleed out onto the street the temp dropped back down to 198. After another 10 driving surface roads at 55MPH it was back up to 210 or so. Very happy with the results.