Engine Temp Concerns - JeepForum.com
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post #1 of 37 Old 07-10-2019, 07:09 PM Thread Starter
Z_MAN
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Engine Temp Concerns

What are your guys' engine temps?

I'll start by saying that my engine usually runs very cool. It takes some time for it to get up to temp. More recently it's been getting "hot" to me. The gauge is now reading about 210 or so when it was usually reading about 170 (my guess). I will say it has been 100 degrees outside consistently; mornings are warm and morning traffic leaves it at the standard 170. The other day on the highway (100 degrees) it got to about 215/220 and it freaked me out. The past year has shown much lower temps.

I changed my oil and there's no coolant leaking into it. I've added a little bit of coolant here and there but nothing crazy.

Here's my concern. I cold started the jeep with the cap off. The radiator looked fine. I couldnt see any fluid movement though. When it approached temp i saw a little smoke leave the radiator, then fluid bubbled out. Then stopped , then started again. Quite a bit actually. Does this sound like a thermostat problem , or water pump? Where would you start ?

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post #2 of 37 Old 07-10-2019, 09:06 PM Thread Starter
Z_MAN
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The more I read and research, these engines are OK from 210 to 225 or so in hot summer Temps. I'm just not used to this.

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post #3 of 37 Old 07-10-2019, 09:36 PM
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Originally Posted by Z_MAN View Post
What are your guys' engine temps?

I'll start by saying that my engine usually runs very cool. It takes some time for it to get up to temp. More recently it's been getting "hot" to me. The gauge is now reading about 210 or so when it was usually reading about 170 (my guess). I will say it has been 100 degrees outside consistently; mornings are warm and morning traffic leaves it at the standard 170. The other day on the highway (100 degrees) it got to about 215/220 and it freaked me out. The past year has shown much lower temps.

I changed my oil and there's no coolant leaking into it. I've added a little bit of coolant here and there but nothing crazy.

Here's my concern. I cold started the jeep with the cap off. The radiator looked fine. I couldnt see any fluid movement though. When it approached temp i saw a little smoke leave the radiator, then fluid bubbled out. Then stopped , then started again. Quite a bit actually. Does this sound like a thermostat problem , or water pump? Where would you start ?
Skip what is 'supposed' to be for anyone else. Yours runs a certain way, consistently, and now it's different. A sticking thermostat is a good (and cheap) bet.

With a cold motor the thermostat will be closed and only a small amount of water moves through the heater bypass cutout. The upper hose will stay cold until the 'stat opens. Then you'll get a burst of steam and moving water that will overflow slightly. You should continue to see circulation at the neck, but little overflow, as the heat expansion settles. That sounds like what you described.

Water pumps typically start to weep out of the 'weep hole' on the bottom of the housing as the seal on the shaft wears out. That usually leaves a tiny drip or trail you can spot when parked. You won't see that with the motor running though. For 5 - 8 bucks I'd do the 'stat because it's cheap insurance. If that doesn't solve the heat issue, you can move on to the water pump. OR...see below

You did mention adding some fluid every once in a while??? Mixture could now be too diluted lowering the boiling point of the coolant. Rust could also be interfering with heat transfer. Might be time for a back flush or a radiator/system cleanout. Followed by fresh antifreeze.
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post #4 of 37 Old 07-10-2019, 09:51 PM Thread Starter
Z_MAN
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Thanks for the heads up. I just ordered a thermostat. 195 degree which is apparently what we use. Which is weird since my gauge always read lower. We'll see. And yes, I do my best to do the half and half mixture but I'm sure I am not perfect. I have an aftermarket aluminum radiator and it looks great, zero corrosion and zero rust but I'm not against a flush and fill.

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post #5 of 37 Old 07-10-2019, 11:24 PM
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Quote:
Originally Posted by Z_MAN View Post
Thanks for the heads up. I just ordered a thermostat. 195 degree which is apparently what we use. Which is weird since my gauge always read lower. We'll see. And yes, I do my best to do the half and half mixture but I'm sure I am not perfect. I have an aftermarket aluminum radiator and it looks great, zero corrosion and zero rust but I'm not against a flush and fill.

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Ours runs at 190 until I tap on the temp gauge, then it reads 210. Use a laser heat sensor on the back side of the thermostat housing when it is at tmp and running for a fairly close reading if you can't trust the gauge.

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post #6 of 37 Old 07-11-2019, 04:45 AM
Que89YJ
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If you're in New Mexico I would get the lower setting Tstat. They do have ranges they open at. Get a 185 and you might consider a 180 if you can find it. Overheating/getting hot on the freeway is not normal. Its usually where the cooling system operates the best with airflow being high enough to push past the radiator without the fans help. If you consistently run high on the freeway I would look at the rad fan clutch. It is suppose to allow the fan to freewheel when cold or spin free when the pressure pushes past the rate the fan is maxed at with engine rpm.

When cold the fan should spin free (Slight resistance). Grab it and spin it and see what you get.

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post #7 of 37 Old 07-11-2019, 05:41 AM
gutthans
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Originally Posted by Z_MAN View Post
Thanks for the heads up. I just ordered a thermostat. 195 degree which is apparently what we use. Which is weird since my gauge always read lower. We'll see. And yes, I do my best to do the half and half mixture but I'm sure I am not perfect. I have an aftermarket aluminum radiator and it looks great, zero corrosion and zero rust but I'm not against a flush and fill.

Sent from my Mi MIX 2S using Tapatalk
Rust/scale will form on the interior of the block. It usually shows up as red sludge in the overflow, but depending on how long the motor sat dry while you changed out, the soft 'muddy' gunk could turn hard on interior surfaces, reducing heat transfer and 'hiding' from you.

For the future you might want to consider a 'sacrificial anode' for the coolant. There is electrolytic action on the aluminum that over years of keeping the vehicle may eat a hole through the metal. I can't swear that it's an imperative, but it's simple enough to install in a housing or drop in the overflow tank.
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post #8 of 37 Old 07-11-2019, 07:52 AM Thread Starter
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I think a little history on my Jeep would help too. It has an electric fan and not a fan clutch. The previous owner installed this. It is a pull fan instead of a push fan, so it's behind the radiator. It is connected to a toggle switch and does not turn on and off by itself. The original owner said he did this for crawling and to have the option to start cooling before things got hot. This was originally an annoyance but it keeps me more engaged and it's been fine so far. I always remembered the e-fan sounding LOUD....and now it's just loud. One thing I am noticing is that when I used to toggle the fan off and on, it would cool the engine very fast. It would take it from 210 to about 170 in a minute or so. Now it's a bit slower.

And now, when I turn the fan on, I no longer see the quick amp draw on the battery gauge. It used to take a little dip when I turned the fan on and now it doesn't. I'm not sure what any of this means or how you'd test that issue.

I did a test today going to work, the engine temp was LOW like it usually was. I left the fan off for about 20 minutes in bumper to bumper traffic. It finally read about 195/200 and I switched the fan on and it came down close to its usual temp. Then I took a little freeway detour with the fan on and it just slightly heated up, but I'll test that more today going home.

I did contact the seller on eBay and they are now going to send me a 180 degree t-stat.
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post #9 of 37 Old 07-11-2019, 08:26 AM
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Do you know what Tstat was installed by the original owner?

Edit: also to note is that it is not uncommon for Tstats to be duds out of the box. Verify it before install by boiling it in water with a thermometer to see when it clicks open

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post #10 of 37 Old 07-11-2019, 08:30 AM Thread Starter
Z_MAN
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I have no idea about the thermostat. I'd imagine it's stock. I'll definitely test the t-stat in boiling water when it comes in.
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post #11 of 37 Old 07-11-2019, 09:05 AM
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I wouldn't turn a single bolt until I had verified actual temperatures. Guaranteed the dash gauge is not correct.
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post #12 of 37 Old 07-11-2019, 09:06 AM Thread Starter
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I wouldn't turn a single bolt until I had verified actual temperatures. Guaranteed the dash gauge is not correct.
I do have a heat gun, so I should probably do this today. If the gauge is wrong, is that a gauge problem...or a sensor problem somewhere, and how the heck do you know haha
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post #13 of 37 Old 07-11-2019, 09:16 AM
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I do have a heat gun, so I should probably do this today. If the gauge is wrong, is that a gauge problem...or a sensor problem somewhere, and how the heck do you know haha
Usually a cluster problem with corrosion. Are all your other gauges accurate? If they are you're lucky.

If you decide to replace the sender, there is a lot of bad info in the parts catalogs out there. Verify your new one is physically the correct length, and verify that it reads resistance correctly before you trash your old one.

My temp runs pretty consistently at the first mark below 210, unless I'm climbing a long hill and then it might creep up to the 210. I don't even know if those temps are actual, but I've become comfortable with them. And they haven't changed through several t-stat changes (I change them anytime the system is involved in a repair) and also before/after a radiator/fan clutch swap. So my gauge is at least consistent, if not accurate.

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post #14 of 37 Old 07-11-2019, 09:23 AM Thread Starter
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Fair enough. For example, this is where my gauge ALWAYS reads, or at least did. Probably isn't correct though right? Now it creeps up a little past 210 when I'm on the freeway. If it makes a difference, I have a 3 speed Automatic Transmission, so 65mph is 3k rpm.
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post #15 of 37 Old 07-11-2019, 09:45 AM
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A thought!
Engine temps were engineered by OEM to allow "all" systems to work at their most efficient levels, together, when at OEM designed operating temp.
If OEM calls for 195 deg thermostat, that would be so cooling, fuel, spark, air, exhaust, etc, should all be working together at peak performance levels. When you run temps cooler/hotter it effects one or more of those systems to not perform the same way it was designed at OEM levels. Cooler can be too cool sometimes!
Not that it really makes much difference in the long run on the rigs we all own and enjoy, but something to be said about OEM, they put a lot of money/time out there to figure out the base vehicles we all play with!
Oh yes, replacing radiator cap too, if it hasn't been done in awhile. Need to maintain correct pressure in the system so it works right
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