Running hot at idle normal?

[adventureboss]

I feel like there's no general census on this, some people say that the TJ's cooling system sucks and others say it has more than enough capacity, but I'm just wondering specifically about coolant temps at idle. It was 90+ degrees today, and going through a drive through I watched the coolant temps hit 230 a couple times (OBD scanner) when I was sitting there with the AC on. The dash temp gauge stayed pretty much at 210, so it lies. Turning the AC off or increasing my RPM to 2k+ brought the temp down of course, but I'm wondering if this is just normal for these old Jeeps.

Reason I ask is because I've literally checked and replaced everything in the cooling system, used OEM parts, and it's basically brand new and has done this for as long as I've had it. I suppose I could have got a bad fan clutch or something, but I can hear it engage and disengage when I'm driving around on hotter days so I'm assuming it's working okay. Is it just normal for them to run hot when it's hot outside and you're idling? In other conditions, even when driving up the mountains when it's 115 outside, I've never seen the temp on my OBD scanner go above 215. It's only when idling. It never overheats, but does get pretty hot. As far as I can tell there is nothing wrong with my Jeep. I also have done several flushes.

I asked my mechanic about it and he says that it's normal and it's just that older cars with fan clutches were not meant to sit and idle for 30+ minutes in the heat. Thoughts? How hot does yours run when it's hot out and you're idling?

 

[KennethS]

Idling means lower engine RPM, which means the water pump and fan are turning slower, which means reduced cooling capability. That is “normal” in the sense that any / all engines will operate the same.

I would not worry about it.

 

[DuckNut]

Your temp gauge does not lie. It may not be accurately calibrated. But more importantly the temp sensor has a delay in it's output to the gauge. It is routed through the PCM, smoothed out and sent to the gauge.

When you start your jeep in the morning and start warming it up the thermostat will open and cooler fluid will enter the block. Ever see the gauge go down in this situation?

 

[xXDavidCXx]

I feel like there's no general census on this, some people say that the TJ's cooling system sucks and others say it has more than enough capacity, but I'm just wondering specifically about coolant temps at idle. It was 90+ degrees today, and going through a drive through I watched the coolant temps hit 230 a couple times (OBD scanner) when I was sitting there with the AC on. The dash temp gauge stayed pretty much at 210, so it lies. Turning the AC off or increasing my RPM to 2k+ brought the temp down of course, but I'm wondering if this is just normal for these old Jeeps.

Reason I ask is because I've literally checked and replaced everything in the cooling system, used OEM parts, and it's basically brand new and has done this for as long as I've had it. I suppose I could have got a bad fan clutch or something, but I can hear it engage and disengage when I'm driving around on hotter days so I'm assuming it's working okay. Is it just normal for them to run hot when it's hot outside and you're idling? In other conditions, even when driving up the mountains when it's 115 outside, I've never seen the temp on my OBD scanner go above 215. It's only when idling. It never overheats, but does get pretty hot. As far as I can tell there is nothing wrong with my Jeep. I also have done several flushes.

I asked my mechanic about it and he says that it's normal and it's just that older cars with fan clutches were not meant to sit and idle for 30+ minutes in the heat. Thoughts? How hot does yours run when it's hot out and you're idling?

What brand radiator cap?

 

[JKP]

230 @ 90 ambient while idling with AC on is not normal.

If you didn't replace the fan clutch, you haven't rebuilt the cooling system.

 

[bohuggabee]

I feel like there's no general census on this, some people say that the TJ's cooling system sucks and others say it has more than enough capacity, but I'm just wondering specifically about coolant temps at idle. It was 90+ degrees today, and going through a drive through I watched the coolant temps hit 230 a couple times (OBD scanner) when I was sitting there with the AC on. The dash temp gauge stayed pretty much at 210, so it lies. Turning the AC off or increasing my RPM to 2k+ brought the temp down of course, but I'm wondering if this is just normal for these old Jeeps.

Reason I ask is because I've literally checked and replaced everything in the cooling system, used OEM parts, and it's basically brand new and has done this for as long as I've had it. I suppose I could have got a bad fan clutch or something, but I can hear it engage and disengage when I'm driving around on hotter days so I'm assuming it's working okay. Is it just normal for them to run hot when it's hot outside and you're idling? In other conditions, even when driving up the mountains when it's 115 outside, I've never seen the temp on my OBD scanner go above 215. It's only when idling. It never overheats, but does get pretty hot. As far as I can tell there is nothing wrong with my Jeep. I also have done several flushes.

I asked my mechanic about it and he says that it's normal and it's just that older cars with fan clutches were not meant to sit and idle for 30+ minutes in the heat. Thoughts? How hot does yours run when it's hot out and you're idling?

Ive never had mine hit above 210 on the gauge. But it will heat soak. Mine is the 4.0. These engines are infamous for it. Even in the wrangler with a large engine bat. I cant sit too long or i get sputtering. One time some dumb cops were traffic training. I had to rev my engine because it was particularly hot. So i could burst the fan. He thought i was insulting him. So he kept me longer. And wouldnt let me go... i have bosch 4 hole injectors too. Which help with engine knock and smooths the running of my engine. However, they cant handle engine heat and will cause pre combustion, and start to sputter . Sometimes our construction crews hold up traffic far too long. One time i sat for 30 minutes for no reason. Just shut the car off... people today have no idea how older beasts work. And they think they can just make you wait all day at your expense.