Cooling system temp spike.

[Mudderoy]

I was driving home today, maybe 10 minutes into my drive home. Got on the highway and ran the speed up to 70 mph. I had the A/C on as the temp inside the Jeep wasn't hot, but warm. Running the OBDII app on my phone I noticed the temp going to 220 then 224, 226, 228 after only about a minute I was at 232, 234. That's when the traffic started slowing down. I tried A/C off, back on didn't seem to make a difference.

May have dropped 2 degrees then went back up.

I was thinking maybe the electric fan wasn't coming on.

Slowing down to 50 seemed to drop the temp pretty rapidly to 224 and it held there.

Taking a different way home, one that I could pull off somewhere and check the electric fan.

I found a place to pull over. A/C was off but electric fan was on, temp above 220 so that was right. I checked the upper hose, couldn't squish it, it was full.

Checked the overflow bottle, it wasn't empty, not even close. While I was looking things over the electric fan went off.

Checked the temp, 215. As I drove the rest of the way home, temp rose to 220, then while just before getting home I sat at a light, and 213, 210. Took off, 208, 206...

I'm thinking thermostat, or maybe low coolant.

[4.3LXJ]

Yeah, tstat could be al little sticky

[Mudderoy]

206 - 208 this morning 70+ mph no A/C. Foggy and naturally air temps were lower. They weren't high yesterday though.

Anyway no A/C going home tonight and we'll see what it does by the same spot. :D

Oh checked the coolant level in the radiator this morning, full and very green.

[msmoorenburg]

could have been air in the system

[Mudderoy]

Hit 235 yesterday, this time with the A/C off. It starts getting hot about the same "geographical" place both times.

I was back to 210 by the time I got home, but I was running the heater, and driving on the back streets by then.

Just doesn't like the highway in 80 degree air temps. Yes I said 80.

[abebehrmann]

Could it be a bad water pump?

[Mudderoy]

Could it be a bad water pump?

I guess, but it has maybe 1,000 miles on it.

[cpttuna]

mech clutch fan bad?

[abebehrmann]

I guess, but it has maybe 1,000 miles on it.


Hmm, well that prob wouldn't be it. Was thinking since it heats up at speeds and tends to cool off when you go slower that might be it. I wouldn't think it would be anything to do with the fans since I've been told at higher speed they don't really do too much. I'm stumped.

Didn't this engine do something like this when it was in the vehicle the first time?

[Mudderoy]

Hmm, well that prob wouldn't be it. Was thinking since it heats up at speeds and tends to cool off when you go slower that might be it. I wouldn't think it would be anything to do with the fans since I've been told at higher speed they don't really do too much. I'm stumped.

Didn't this engine do something like this when it was in the vehicle the first time?

Both ran hot. This spikey stuff is different, something isn't working like it is supposed to. I bet it's the thermostat.

[Brasscatz]

If it was the same geographical location, you might be near some sort of ancient vortex. Have you checked to see if there are any stone circles nearby? Or even possibly a star gate?

[dagod16]

Change thermostat. Install one with the failsafe so it will break open.

[Carves]

Both ran hot. This spikey stuff is different, something isn't working like it is supposed to. I bet it's the thermostat.


tis the most likely culprit ... You changed it yet ??

Fan belt tension OK ??

[Mudderoy]

tis the most likely culprit ... You changed it yet ??

Fan belt tension OK ??

I have not changed it yet. I'll check the belt, but I did use my graduated thumb the other day after putting in the freeze plugs.

[Carves]

I have not changed it yet. I'll check the belt, but I did use my graduated thumb the other day after putting in the freeze plugs.


;)

Dont forget that the thermostat housing bolts only need to be tightened up to, two clicks of the elbow .. :D

[4.3LXJ]

;)

Dont forget that the thermostat housing bolts only need to be tightened up to, two clicks of the elbow .. :D

Pulled a busted one out for a friend last week that was tightened up to three clicks :smiley-taunt002:

[Poorboy]

Clogged radiator will cause issues like those as well. I flushed mine when I changed the heater houses and diverter valve... Now I've got a pinhole in my radiator... Should've never flushed it.

[4.3LXJ]

Got rid of all the junk plugging up the hole?

[Mudderoy]

Change the thermostat. Had two, thought I'd try the 180 just for grins. I know it doesn't vary the top temp.

Hit 234 on the drive into with 48 degree air temps.

I checked the electric fan, running, feels like good air flow, but that doesn't explain the 234 at 65 mph.

Also temp goes down to 220ish (221) pretty quick when I slow down to 40 mph or so. 217 sitting in traffic. Rose back to 219/221 while driving at 50-55 mph.

[Poorboy]

Got rid of all the junk plugging up the hole?

Yes. :( I'm going to redneck fix mine (Bars leaks) until warmer weather when I have the time and money to replace it. For now, it's holding.


Change the thermostat. Had two, thought I'd try the 180 just for grins. I know it doesn't vary the top temp.

Hit 234 on the drive into with 48 degree air temps.

I checked the electric fan, running, feels like good air flow, but that doesn't explain the 234 at 65 mph.

Also temp goes down to 220ish (221) pretty quick when I slow down to 40 mph or so. 217 sitting in traffic. Rose back to 219/221 while driving at 50-55 mph.

I'm still betting on my first thought, Radiator and cooling system has junk in it.

In noticed on my latest trip to Umatilla, OR that I had temp spikes above 70MPH. I passed a couple big rigs that were doing fifty and she spiked up to about 240, then dropped right back down (It's always had some wave of the needle, but never above 220 or so when passing). I think, Mudderoy, you and I have the same issue.

[Mudderoy]

I did the standard procedure to fill the cooling system Sunday, so I'm thinking it's full, but it may not be. I'll check it before heading home to make sure. I think that radiator is pretty new, 2 years old, so I hope it's not clogged.

[BlackYeti]

With heat running at high speeds like that, what kind of temps is your trans getting to?

[Poorboy]

I did the standard procedure to fill the cooling system Sunday, so I'm thinking it's full, but it may not be. I'll check it before heading home to make sure. I think that radiator is pretty new, 2 years old, so I hope it's not clogged.

Lets hope not...

I think I found my issue this morning though... :banghead:

http://youtu.be/pAw7Ytk3JCM

I made the video for my Friend Kevin...

[Mudderoy]

Hit 242.6 today in 69 degree air temps.

[Mudderoy]

I forgot that I upload the data to the Torque site, show here's this mornings run...


7122

[Mudderoy]

Do you guys remember that Jeep dealership I stopped in after the last motor dropped a valve?

We'll I'll be stopping there today to pick up...

MOPAR
Thermostat $21.50
Gasket $5.00
Temp sensor $57.60
IAC $126.00 (Getting a replacement since Matt grabbed an old one off another Jeep back when it was at his shop)

Damn Jeep! :spongebob:

[autotech98]

Just empty every pocket...that always cracks me up. Till i have to do it

Sent from my SAMSUNG-SGH-I547

[Mudderoy]

The only thing I had time to replace last night was the temp sensor.

Other than that, the BIG difference is air temps of 37 degrees. Maybe I just need to move. :D

7127

Looking at this graph I noticed something.

You see the temp rise until it hits 89 degree Celsius. That's 192.2 in normal measurements. It rapidly drops to 176, then rises 187.7, drops to 176, then rises to 189.5. I think it's pretty clear this is the thermostat opening and closing. At this point there is little change in the coolant temp the rest of the trip.

[abebehrmann]

That's after the install of the new parts?

[Mudderoy]

That's after the install of the new parts?

Sorry (damn work) :D I just updated the post with more information.

[Mudderoy]

Friday it was about 60 degrees out and over the past couple of days I was only seeing 188 no matter how fast I went. That changed as the air temps increased.

I hit 228 Friday afternoon, nearing the house, on the highway at 70+ mph.

Something has changed. I didn't have this issue after the engine was installed.

The water pump is new. Since it's obvious the thermostat is opening and closing, you can see it on the graph, it must be the radiator.

I am thinking about removing the radiator from the Jeep and pouring some CLR in it in an attempt to clean it out.

I guess I could do the entire system. What do you think?

[Carves]

Could be that you have some gunk in the inlet tank, blocking a couple of the lower tubes ??

Have you got any way of measuring the core temps i.e. lower tube area compared to uppers ??


Stoopid crossflow radiators .. :rolleyes:

[Mudderoy]

Could be that you have some gunk in the inlet tank, blocking a couple of the lower tubes ??

Have you got any way of measuring the core temps i.e. lower tube area compared to uppers ??


Stoopid crossflow radiators .. :rolleyes:

I have a IR temp gun.

I'm wondering if something got into the cooling system when the #5 cylinder wall broke open. It may be oily at the bottom of the radiator.

[Mudderoy]

As air temps have increased there are no more temp spikes, it's a constant.

Here's what I've found.

At 65 mph it will hover around 230, 70 mph it will increase to 242.

65 mph is 2500 rpm 70 a little more 2600 (maybe)

The interesting part is one I get off the freeway and drive 50 mph the temp starts dropping. Over a mile from the freeway to the first light.

50 mph is about 2000 rpm.

So 50 mph, 2000 rpm the coolant temps drop, at 65 mph 2500 rpm temps increase.

I'm really wondering if the catalytic converter is just not allowing enough exhaust out. The cooling system seems to be working well once the load is reduced.

I'm at about 215 by the time I get to the house.

I'd like to try a high flow catalytic converter but so far everything I've seen doesn't have a O2 bung and I'm avoiding muffler shops, rather do it myself.

[Poorboy]

I can't remember if anyone mention the spring in the lower radiator hose yet or not....

If the spring is missing, sometimes the hose can collapse and partially block coolant flow out of the radiator.... It would most likely occur at higher RPM as the waterpump would be drawing more liquid through....

[abebehrmann]

As air temps have increased there are no more temp spikes, it's a constant.



Here's what I've found.



At 65 mph it will hover around 230, 70 mph it will increase to 242.



65 mph is 2500 rpm 70 a little more 2600 (maybe)



The interesting part is one I get off the freeway and drive 50 mph the temp starts dropping. Over a mile from the freeway to the first light.



50 mph is about 2000 rpm.



So 50 mph, 2000 rpm the coolant temps drop, at 65 mph 2500 rpm temps increase.



I'm really wondering if the catalytic converter is just not allowing enough exhaust out. The cooling system seems to be working well once the load is reduced.



I'm at about 215 by the time I get to the house.



I'd like to try a high flow catalytic converter but so far everything I've seen doesn't have a O2 bung and I'm avoiding muffler shops, rather do it myself.


To test this theory, you could try driving at 50mph, not in D, but in 3 and see what your temps do.

[Mudderoy]

To test this theory, you could try driving at 50mph, not in D, but in 3 and see what your temps do.

Great idea. I so seldom have put the transmission in "3" I didn't realize it would raise the RPM so much.

50 mph goes from about 2,000 rpm to 2,500 rpm

First I wanted to verify that the temp was going down, so when it dropped from 240 to 231 after about 1/2 mile I dropped it from drive to "3" on the shifter.

It dropped to 230 and held there a bit, then started to rise, but only to about 233, then I had to turn into the neighborhood where they frown on driving and swerving around kids at 50 mph.

I'll try it again tomorrow afternoon and since I have confirmed the coolant temp drop at 50 mph, I'll just shift into "3" as soon as I get off the freeway.

Again, great idea!

[Mudderoy]

Exited the freeway, I was up around 240 (reading gauge). Put it into 3rd, and started up the Torque app. It was down to 231 (I'm assuming it was at 240 I may be wrong). Driving 50 mph it dropped to 228 and stayed there until I slowed down. It dropped to 226 by the time I got home.

I did locate my IR temp reader, and broke it out when I pulled into the driveway. The engine just isn't that hot! Showing 228 on the Torque app (OBDII), scanning the block... 240, canning the thermostat housing? 209 to 214. The only thing that I could find that was hot was the header, about 374 degrees. Cornfused.

[Mudderoy]

Ran 242 for a good 7 miles today. After getting off freeway, about 1/2 mile, I pulled into a gas station and IR scanned a few areas.

The hottest place I could find on the thermostat housing was 217.

Now I'm wondering if that's a reliable way to tell what the coolant temp is.

Very strange, or I'm just not understanding something.

[Carves]

Ran 242 for a good 7 miles today. After getting off freeway, about 1/2 mile, I pulled into a gas station and IR scanned a few areas.

The hottest place I could find on the thermostat housing was 217.

Now I'm wondering if that's a reliable way to tell what the coolant temp is.

Very strange, or I'm just not understanding something.


Theoretically ... the housing should be as hot as the coolant,

... but ... you've stopped, opened the bonnet, and changed the circumstances a little .. ;);)

One would expect a little variation, but 217 - 242 would seem a little wide.

You done all the ohm tests on the coolant temp sensor to ensure it is accurate ??

I'm now thinking you may need to verify temps with another temp gauge,

... got something like this handy ??

http://www.xjtalk.com/showpost.php?p=94202&postcount=1

[Mudderoy]

Theoretically ... the housing should be as hot as the coolant,

... but ... you've stopped, opened the bonnet, and changed the circumstances a little .. ;);)

One would expect a little variation, but 217 - 242 would seem a little wide.

You done all the ohm tests on the coolant temp sensor to ensure it is accurate ??

I'm now thinking you may need to verify temps with another temp gauge,

... got something like this handy ??

http://www.xjtalk.com/showpost.php?p=94202&postcount=1

Same thoughts here. I was investigating a 2nd, mechanical temp gauge that I could mount in the engine bay. I was going to "T" off the heater core line, the one that runs to the heater core off of the thermostat housing.

I like that test unit though.

One other thing I should mention. A friend told me to clean my grounds, especially since the engine was recently changed. I haven't done that yet. I believe the advice was to add a few more as well.

Mindful of the changing temp, I pulled off the highway quickly, less than a minute. And I didn't take the time to put the hood stand up, just IR'd the thermostat housing right after raising the hood, 10 seconds? Checking the Torque app I was still reading 240.

I understand what you're saying about changing the conditions. I do need a secondary way to read the coolant.

[Mudderoy]

Those temp reading units are neat, and unless I missed the part where it says you have to calibrate them to read engine temp correctly it also answers my question about reading the temp from the thermostat housing.

The only other thing I have read is that reflective surfaces may not read as accurately as a dark or black surface. The thermostat housing isn't mirrored but it isn't dark either. Still 217 to 240? The IR scanner I have is a FLUKE and they make pretty good electronic test equipment.

[Mudderoy]

Just ordered the TM1, thanks Carves. I priced up a $20 mechanical temp gauge and thought about installing it in the heater core line then mounting it in the engine bay, but after mulling it over this TM1 unit I can use on my Jeep, the TJ and the other XJ. Just move it around as needed. Obviously I'm getting the one in Fahrenheit (God's temp measurement)

http://www.sig.itel.net/images/TM4-EBAY-cogs.jpg

[Carves]

Obviously I'm getting the one in Fahrenheit (God's temp measurement)


:smiley-laughing021:


Fahrenheit is fine for you 13 toed texas hillbillies ... but down here, we only have ten toes,

... so counting in metric, works good for us .. :p .. :D


That IR gun you have ... does the owners manual spec what distance, i.e. the DISTANCE TO SPOT (D:S) RATIO, has to be from a target for a correct reading ??

That little one I bought, is only 1:1 so it needs to be real close, for a correct reading.


Spend some time getting used to what the TM1 is telling you ... Do a few test comparisons with the Fluke and the XJs display.

[abebehrmann]

:smiley-laughing021:


Fahrenheit is fine for you 13 toed texas hillbillies ... but down here, we only have ten toes,

... so counting in metric, works good for us .. :p ...



Crazy Aussie logic...

Next you're going to try to tell us that water melting at 0C and boiling at 100C makes more sense than 32F and 212F. :D

[4.3LXJ]

And body temp is 37.5° Sounds kind of chilly to me :D

[Mudderoy]

:smiley-laughing021:


Fahrenheit is fine for you 13 toed texas hillbillies ... but down here, we only have ten toes,

... so counting in metric, works good for us .. :p .. :D


That IR gun you have ... does the owners manual spec what distance, i.e. the DISTANCE TO SPOT (D:S) RATIO, has to be from a target for a correct reading ??

That little one I bought, is only 1:1 so it needs to be real close, for a correct reading.


Spend some time getting used to what the TM1 is telling you ... Do a few test comparisons with the Fluke and the XJs display.

I'll have to confirm this is the correct model, but it looks like it...

Distance to spot size 10:1 calculated @ 80% energy
Typical distance to target (spot) Up to 2 m (6 ft)
http://en-us.fluke.com/products/thermometers/fluke-62-mini-thermometer.html#techspecs

Hillbilly?!?!?! I'll have you know my cousin, ahhh my Mom takes offense at that!

[Mudderoy]

And body temp is 37.5° Sounds kind of chilly to me :D

Geez if that body was your girlfriend it could be considered necrophilia! Actually if I had a girlfriend that would soon be my temp. :D

[NW99XJ]

I'd like to see a version of this in a universal A-pillar mount style.
http://gallery.lisaandmike.org/albums/carstuff/PICT3858.jpg

http://static.summitracing.com/global/images/prod/mediumlarge/atm-10101_ml.jpg

http://www.4wheelparts.com/aux_incl/images.ashx?i=007093.jpg&partNo=AMG&w=330&h=330

[nickxj94]

I've been experiencing the same issues this week. My factory gauge said the engine was starting to get in the danger zone. I got one of them lazer temp readers. Tstat housing was 195,checked heater hoses all in different spots, under 195. Tested top of radiator to the bottom. All while running and factory gauge said 220.. So replaced the sending unit on tstat housing, and added 1.5 spacers on the hood. Temp still seems off but not like it was before. Now at 210 (operating temp) by factory gauge, lazer gun says 174 on tstat. Only thing i did different was added some different kind of coolant (gold) from what i was running in the old body. May try green coolant again see if it changes.

http://images.tapatalk-cdn.com/15/04/23/85970a03eeb0c31b641fb03cc7d5408e.jpg
http://images.tapatalk-cdn.com/15/04/23/288e473f3bcf41c55eeedaad6d28e4a6.jpg

[Mudderoy]

Okay since I hit 250 (OBDII reading) coming home on Thursday I got my a$$ out there and hooked up the new toy.

I ran it for a bit and it differed from the OBDII reading as much as 30 degrees as it was warming up.

Now once the OBDII temp hit 191 I saw the thermostat open and the temp dropped to 179. It's a 180 degree thermostat show I guess that could be an indication that the OBDII reading is 11 degrees off or the thermostat opened 11 degrees past 180.

The TM1 reading never got about 176 while the OBDII was 186 (remembering those numbers by memory)

It could be the metal of the thermostat housing is just taking longer than the coolant to heat up and that would be the reason for the temp difference.

The real test will be under long sustained load where the metal has time to hit the same temp as the coolant.

I just have to wonder, does the thermostat housing EVER hit the coolant temp, or will it always be cooler? I can see that it should hold the temp longer than the coolant.

Dunno, all new territory.

[Mudderoy]

First measurements after 10 to 15 miles of driving...

High of 221 (OBDII)
High of 199 (TM1)

[nickxj94]

Mine is about 18* off Still was 22 before i changed the temp sender.

[Mudderoy]

Mine is about 18* off Still was 22 before i changed the temp sender.

Not sure if I posted it here, but I have a new Chrysler/Jeep sending unit, maybe a month ago when I started seeing this issue but didn't notice any running hot ill effects.

[Mudderoy]

75 - 80 mph last couple of miles coming home...

OBDII reading (242)
TM1 reading (210)

{facepalm!}

Most of the 20 miles it was 197 or less.

[nickxj94]

It's a demon! 👺

[4.3LXJ]

Gremlins

[Carves]

Some numbers for ya Mr Mudderoy.

Bit cool here today ... about 74*f ... Might have to have a, toasted, vegemite sandwich and a cuppa tea for lunch,

... instead of a plain one and a beer .. :D


... anyways, fired it up and left it it idling in driveway for 30min or so.

Numbers started out similiar, then a big difference for a while, and then started to match up again,

... will give you some more numbers for reference next time it goes for drivies.


Cold Start Temps

OBD2 ...77* ... 95* ... 140* ... 175* ... 195* ... 204* ... 203*

TMI .....75* ... 90* ... 120* ... 145* ... 175* ... 190* ... 198*

IR .................................................. ...................... 197*



Numbers are approx' ... since I'm using metric settings,

... and the battery in one of my calculators is getting a bit flat, for doing conversions .. ;);)


http://thumbs.dreamstime.com/x/australian-flag-thongs-sandals-18451642.jpg

[Mudderoy]

Some numbers for ya Mr Mudderoy.

Bit cool here today ... about 74*f ... Might have to have a, toasted, vegemite sandwich and a cuppa tea for lunch,

... instead of a plain one and a beer .. :D


... anyways, fired it up and left it it idling in driveway for 30min or so.

Numbers started out similiar, then a big difference for a while, and then started to match up again,

... will give you some more numbers for reference next time it goes for drivies.


Cold Start Temps

OBD2 ...77* ... 95* ... 140* ... 175* ... 195* ... 204* ... 203*

TMI .....75* ... 90* ... 120* ... 145* ... 175* ... 190* ... 198*

IR .................................................. ...................... 197*



Numbers are approx' ... since I'm using metric settings,

... and the battery in one of my calculators is getting a bit flat, for doing conversions .. ;);)


http://thumbs.dreamstime.com/x/australian-flag-thongs-sandals-18451642.jpg

This is great information, thank you!

Without taking the prob and putting into boiling water you can really never tell if it is reading the correct temp.

Matt (msmoorenburg) has told me about three times now to check my grounds. I guess I'm going to have to do it. :P

[Carves]

Matt (msmoorenburg) has told me about three times now to check my grounds. I guess I'm going to have to do it. :P


Nahhhhh.....

Dont give him the satisfaction of maybe, being right .. ;);)


:D:D

[autotech98]

I was gonna say as well know as chrysler wiring is for issues...lol.

Sent from my SAMSUNG-SGH-I547

[autotech98]

My gas gauge likes to change level randomly sometimes. Got some monster cable to replace batt cables and gonna upgrade the chasis and block grounds too

Sent from my SAMSUNG-SGH-I547

[Mudderoy]

It was only 77 today, but I drove it normal on the way home. The alarm went off after a good 80 mph run and just coming to a stop exiting the highway. Damn thing was set for 212 alarm!

Anywho more testing is in order, especially with the higher air temps, but it looks promising.

Thanks for the suggested temp unit Carves!

[Mudderoy]

I am really happy. I took a long drive into Houston today, 80+ air temps. Drove 70 to 80 mph for 30 minutes.

OBDII got up to 250.2, the TM1 said 212.

I can officially make it to the off road park!!!!!

I do need to get the problem with dash gauge temp reading and OBDII temp corrected.

[4.3LXJ]

Good news Tony. It did seem to me the temp was reading too high to not have boiling coolant

[BlackYeti]

Have you ever thought about swapping the gauges from your 99 for a week?
Not positive if its a direct swap or not either. Just food for thought.

[Mudderoy]

Have you ever thought about swapping the gauges from your 99 for a week?
Not positive if its a direct swap or not either. Just food for thought.

Since I'm reading the temperature from the PCM via the OBDII interface I don't think swapping the cluster would make a difference.

[BlackYeti]

Ah yes, forgot about that... Just seems strange still.

[Mudderoy]

Ah yes, forgot about that... Just seems strange still.

It's very strange. The horrible thought I had was what if I've been chasing the heat creep problem for the last 10(?) years and all the time it's been another issue? I'm sure I had cooling system problems in the past but I may not have needed 5 different radiators.

[BlackYeti]

Now I am curious which one of those were actually the most efficient.

[4.3LXJ]

Tony, after you get some more data, I think that maybe we might be looking at a PCM issue. But you need some consistent data to make that call

[Mudderoy]

Now I am curious which one of those were actually the most efficient.

lol yeah! Well the gauge and OBDII still worked and the other radiators let the temp go higher, we just don't know how high.

Things really changed when the heater core was swapped out.

[bruggz351]

Tony, after you get some more data, I think that maybe we might be looking at a PCM issue. But you need some consistent data to make that call

I wonder if this may be a common issue? Perhaps a glich in the Chrysler PCM?

[Mudderoy]

I wonder if this may be a common issue? Perhaps a glich in the Chrysler PCM?

I was thinking about a bad PCM myself. Matt had a problem with his, it had a crack in it and would die after it warmed up.

[NW99XJ]

So swap the PCM from the 98 with the 99, and take it for a drive.
You may notice a difference in what the oil pressure gauge is telling you, but its nothing to worry about.
(i think the sense leads are reversed in the pin layout between the two years - but that is the only difference.)
Take the same exact drive at the same time of day (roughly) and track your results.
Have your OBDII interface up and going for each drive for reference.
This might at least help in troubleshooting the underlying problem...
or at least determine if there's an issue with the PCM's interpretation of the data coming from the coolant temp sending unit.

[4.3LXJ]

I wonder if this may be a common issue? Perhaps a glich in the Chrysler PCM?

That is a good question. We have worked a little on issues with my son's 98 TJ. It always said and even 210 on a 195° thermostat. I don't think it was really that hot. It always seemed incredible to me that if it was getting that far past the thermostat opening in temp that it was so consistent. After seeing this, I think it is a good possibility that the PCMs just don't interpret the data properly

[Mudderoy]

That is a good question. We have worked a little on issues with my son's 98 TJ. It always said and even 210 on a 195° thermostat. I don't think it was really that hot. It always seemed incredible to me that if it was getting that far past the thermostat opening in temp that it was so consistent. After seeing this, I think it is a good possibility that the PCMs just don't interpret the data properly

I told Matt I was just going to put a variable resistor in line with the sensor and adjust the temp to what I liked best. ;o)

[4.3LXJ]

I told Matt I was just going to put a variable resistor in line with the sensor and adjust the temp to what I liked best. ;o)

There ya go, you will feel better for sure

[reddragon72]

Just get it up to temp and open the dash pull the needle off and glue it back on to what the other gauge is telling you :p

[Mudderoy]

Friday I had the dash light go off as the temp rocketed to 250!!!! Well at least that's what the gauge said...

So when your 4.0 over heats does it do this...

Temp climbs to 210 past 210 and seems to stay at that first hash past 210 a long time, then slowly it passes that hash.

BOOM! All of the sudden the needle shoots to 250, that mark right before the next line marked ast 260.

I powered on the Engine Watchdog TM1 and I was sitting at 226 degrees.

My Jeep has always done this and one of the reasons I was always concerned about it sitting at 210. Does your Jeep do the same thing?

[nickxj94]

Friday I had the dash light go off as the temp rocketed to 250!!!! Well at least that's what the gauge said...

So when your 4.0 over heats does it do this...

Temp climbs to 210 past 210 and seems to stay at that first hash past 210 a long time, then slowly it passes that hash.

BOOM! All of the sudden the needle shoots to 250, that mark right before the next line marked ast 260.

I powered on the Engine Watchdog TM1 and I was sitting at 226 degrees.

My Jeep has always done this and one of the reasons I was always concerned about it sitting at 210. Does your Jeep do the same thing?
Mine did that today. I checked it with a laser pointer temp gauge, tstat housing was 219 while stock gauge said 250 in the red, my e fan was on and air conditioning. Didn't smell hot and was not boiling over. I'm at lost. I have my old 94 pcm i may swap it in to see what happens.

[nickxj94]

Ok...i narrowed mine down to the rear temperature sender wire or wiring is broken somewhere or shorted out. I replaced the sender today and it pegged the gauge out.
http://images.tapatalk-cdn.com/15/05/05/db0f863c7c22616443f5355e5b5881b1.jpg
So i checked it with my infrared gun
http://images.tapatalk-cdn.com/15/05/05/74ad6525c369950bc2ac5fc2f8a24522.jpg

Checked tstat housing
http://images.tapatalk-cdn.com/15/05/05/c59ff6c257ad21d5d1dbcc8f08b7200d.jpg

I replaced the water pump today for good measure along with the inlet tube since it blew out today.
Drilled a small hole in the tstat it's self and placed the hole on bottom of housing.

Disconnected the original temp gauge and installed a aftermarket gauge.
http://images.tapatalk-cdn.com/15/05/05/d3da238242fd9d8475638dcbbbbcb3f2.jpg

Let it idle over 30 mins with AC on never did get over 190 degrees. So I'm happy with that.

Mud just disconnect that factory gauge and install a aftermarket lol

[Mudderoy]

Collecting a little more data. Had the check gauges light come on again Tuesday on the drive home. Temp gauge needle at the hash just before the 260.

Turned on the Torque app and it read 251. Plugged in the TM1 Engine Watchdog, 212.

I need to verify this but it looks like if I'm in the 240's the temp gauge needle is just shy of the first hash mark after 210. It seems 250 it's right on that same hash mark, but anything over 250 the needle rockets all the way over to the next to last hash mark.

7609

[Mudderoy]

I got ready before the temp gauge snapped over today. Torque app running and TM1 Engine Watchdog pulled in.

The needle was on that first hash mark past the 210 and as the torque app showed 255 degrees, SNAP, check gauges and that little hash before the last one on the gauge.

Temp on the TM1? 219.

As the temp dropped to 250 the needle drops back down.

I've actually ordered a 1k potentiometer. I'm going to see if I can adjust the resistance at the temp sensor and get my meter and OBDII reading correctly.

[4.3LXJ]

That will be an interesting one if you pull that off Tony

[nickxj94]

Mine broke down today...wouldn't start after work..no fire from coil.

[BlackYeti]

Mine broke down today...wouldn't start after work..no fire from coil.
Did you forget to feed the hamster before you went into work? I've done that before, he just laid around all day instead of charging up the coil.[emoji12]

[nickxj94]

Did you forget to feed the hamster before you went into work? I've done that before, he just laid around all day instead of charging up the coil.[emoji12]
I drove it on lunch about 1 pm. It ran fine went and filled it full of gas.. I replaced the cps still nothing. Ordered a coil be here in the morning. Hopefully that is it.

[Mudderoy]

Yeah my coil died driving down the freeway at 70 mph.

I did forget to mention that I am going to work on grounding stuff, but with all this going on reminds me of what happened the first time it over heated in about 2000, it did the exact same thing. I didn't have the TM1 to know what the real temp was.

[nickxj94]

Driving down the interstate.
http://images.tapatalk-cdn.com/15/05/09/3d30bfcb59a3c302750574c9a5171d09.jpg

[4.3LXJ]

That is a good temp. 195° tstat?

[nickxj94]

That is a good temp. 195° tstat?
180 with a hole drilled in it. Lol

[drakan1908]

Tony, have you seen these? http://www.jegs.com/webapp/wcs/stores/servlet/m20ProductDisplayView?catalogId=10002&parent_category_rn=10123&top_category=10109&categoryId=10125&langId=-1&productId=874786&storeId=10001&pgGrp=catNav This would let you know what the coolant temp. is at a glance. And they come in red! [emoji3]

[Mudderoy]

Tony, have you seen these? http://www.jegs.com/webapp/wcs/stores/servlet/m20ProductDisplayView?catalogId=10002&parent_category_rn=10123&top_category=10109&categoryId=10125&langId=-1&productId=874786&storeId=10001&pgGrp=catNav This would let you know what the coolant temp. is at a glance. And they come in red! [emoji3]

Gave me an error.

[drakan1908]

7623 here is a pic. Sorry link worked for me

[Mudderoy]

As air temps have increased so has my coolant temps. Yesterday the gauge got all the way to 260. Slapped on the Engine Watchdog TM-1 and it ready 224.

Highway temps. Once I get off the highway it raises 2 degrees then drops down to 217 traveling at 55mph.

I think 220 is about normal for 90 degree air temps, what about you guys?

It drops to 210-213 once off the freeway.

[abebehrmann]

As air temps have increased so has my coolant temps. Yesterday the gauge got all the way to 260. Slapped on the Engine Watchdog TM-1 and it ready 224.

Highway temps. Once I get off the highway it raises 2 degrees then drops down to 217 traveling at 55mph.

I think 220 is about normal for 90 degree air temps, what about you guys?

It drops to 210-213 once off the freeway.

Mine is the opposite. When I'm on the highway even in 90+ temps, it runs at 210-212. When I get off and get caught in traffic in high temps, then it will get up to 215-220.

[XJ Wheeler]

Same here. Mines higher when stopped. I put a 195 t-stat in and that's about where it runs while going usually at just about any speed and in this temp (outside) its constantly bouncing off the 220 efan temp.

Sent via messenger pigeon - i talk, he types.

[Brasscatz]

I have no clue. The Honda doesn't have a coolant temp gauge :/

[XJ Wheeler]

I have no clue. The Honda doesn't have a coolant temp gauge :/

Huh!?!?! :what:

Sent via messenger pigeon - i talk, he types.

[Carves]

You got that thing full of eth-gly again ??


Thankfully ... mine does not vary much from 195*-200* during summer. Town or highway.

If it got to 210* ... I'd be wondering whats wrong.

As for these nasty 40* - 65* winter days we're having ... 190*- 195*

[Mudderoy]

I hit 230 on the Engine Watchdog TM-1 yesterday. Cools down pretty quick when I stop doing highway speeds, 55 mph for example.

If you've been following my temp problems over the last 10 years, all this will sound like a repeat, but for those of you that are interested or perhaps can't remember 10 years ago... :P

Ran a static test in the driveway yesterday. 2000 rpm in drive. Went from 204 to 222 in about a minute. Clyde wants me to try coasting at highway speeds and see if temp drops, we both suspect it will.

A test I've done before and will be trying to day is no A/C. I did that this morning and I think I made it to 201, briefly, nearly 15 miles into my journey.

After getting home and the driveway test, I decided it was time to make the resistor change. Specifically to put a variable resistor in line and "adjust" the temp sensor's resistance being read by the PCM.

I did get as far as reading the resistance at 184 degrees on the watchdog, 204 on the OBDII. 790 ohms.

Digging around I found this handy little chart!

http://img.photobucket.com/albums/v123/dos0711/Jeep%20Stuff/CoolantandAirTempChart.jpg

As you can see from this chart I should have been reading about 1,100 ohms for the 184 degrees.

Clyde urged me to try a few more sensors before making this one adjustable. I may still do the variable resistor just for grins to prove it will work and for a post, but we'll see. I have to locate all my temp sensors and boil some water while checking the resistance.

[Mudderoy]

I'm trying to find out if these would make some low pressure in the engine bay and pull in more air through the radiator.

https://www.hylineoffroad.com/sites/default/files/XJ-50HLP_%28Use_As_Main%29.jpg

[4.3LXJ]

Those are nice looking hood vents

[Mudderoy]

Put the prior temp sensor back in yesterday, didn't really see a difference in the readings.

Did another no A/C test on the drive home. 78 degree air temps, but it was Sunny, never went above 203, and that was only briefly. Drove it like Cantab drives his.

[4.3LXJ]

Tony, ever think it might be the temp gauge itself that is off?

[Mudderoy]

Tony, ever think it might be the temp gauge itself that is off?

Sure, but the OBDII is 20 degrees off and the resistance read from the sensor is wrong as well, according to the chart I posted above.