2021 1500 5.7 coolant temp went nuts

[Gravel Roads]

Hi everyone. First time poster here. I have a 2021 ram 5.7 and the coolant temp on the digital readout started changing from when it was new.

I've done a number of searches on this forum and others and I have not been able to find any posts similar to mine.

For the first few thousand miles the coolant temp seem to operate like others have posted on this forum. Running with a low of about 203 degrees fahrenheit once warmed up to about 215 or 217 on the highway. A few months ago it started swinging quickly as soon as I accelerate. For example if it was running at about 206 as soon as you accelerate it would jump to 208 then 210 then 212 within a couple of seconds. After maintaining steady speed or decelerating the temperature would go back down to approximately 206. Sometimes it would drop to 199 and other times it would run up to 228 and then the fans would come on. Now all of a sudden when started when cold at ambient temp the coolant temperature starts shooting up right after cold start and gets to warm up temperature within a couple of minutes. For the first couple of thousand miles it did neither of these things.

The coolant level only dropped in the overflow tank a little bit since it was new. It now has about 8000 miles on it. Out of frustration I replaced the thermostat and purged all the air. This did not solve the problem. One thing that surprised me was the coolant changed smell to a terribly stinky sickly sweet smell, kind of like the old green coolant that has gotten real hot. I see no signs of a blown head gasket other than what I just listed. No apparent coolant in the oil and no smoke out of the exhaust. I have not seen or heard of a 5.7 hemi having head gasket problems. I like this truck and this is frustrating.
I did not take this to the dealer yet. I've had bad experiences before trying to get a problem repaired under warranty with Chevrolet. The bottom line is they didn't want to touch it until it was literally broken down and not running or flashing the check engine light with all kinds of codes. I know what it's like to come up against warranty. I'm pretty sure Dodge won't touch it until it's actually blowing coolant out of the radiator or so hot that it's obviously shouldn't be driven. So I'm trying to gain some experience with these 5th gen Ram pickups so I know if others have had this problem before I go to the dealer. I know this sounds like a head gasket. The pickup is so new that I'm not sure what to think. Has anybody else had or heard of this problem with a 5th generation Ram? I apologize for the long post. I hope I listed the pertinent details. Thank you.

 

[IvoryHemi]

Temps look normal to me

 

[SD Rebel]

Seems completely normal to me, matches up from what I've seen on my RAM.

Normal driving without a load (i.e. not towing), once up to full operational temp, your coolant temp should range from 205F - 230F, cycling through that range pretty regularly. Modern vehicles run at higher temps for better efficiency. I believe the highest you should see while towing is 245F, you will get a warning at about 250F.

If you notice, your analog coolant gauge won't budge at all during all this, because they only show large movements. However, if you put an OBDII reader and look at the live coolant temp data on any of your other vehicles that don't have a digital gauge, you will find they have a wide cycle range as well, usually 20-30 degree swings as the thermostat operates.

 

[Gravel Roads]

Temps look normal

Temps look normal to me

Thank you I will keep an eye on it.

 

[Gravel Roads]

Seems completely normal to me, matches up from what I've seen on my RAM.

Normal driving without a load (i.e. not towing), once up to full operational temp, your coolant temp should range from 205F - 230F, cycling through that range pretty regularly. Modern vehicles run at higher temps for better efficiency. I believe the highest you should see while towing is 245F, you will get a warning at about 250F.

If you notice, your analog coolant gauge won't budge at all during all this, because they only show large movements. However, if you put an OBDII reader and look at the live coolant temp data on any of your other vehicles that don't have a digital gauge, you will find they have a wide cycle range as well, usually 20-30 degree swings as the thermostat operates.

 

[Gravel Roads]

I definitely noticed my temp gauge dosen't respond to changes! I'm going to keep an eye on the huge spikes under acceleration. If it gets worse I'll make a video of it happening and post it. Thank you.

 

[SD Rebel]

I definitely noticed my temp gauge dosen't respond to changes! I'm going to keep an eye on the huge spikes under acceleration. If it gets worse I'll make a video of it happening and post it. Thank you.

Your range isn't unusual, but if you notice some crazy rapid stuff, maybe there could be something there, could even be the sensor itself.

On a side note, many modern vehicles have different coolant temp profile depending on the driving conditions, to maximize efficiency and performance. I haven't bothered to see if the RAM has special cooling profiles, but here is the one on my old BMW E90, just so you can see how varied the temps can be ...

For example, the BMW E90 (2007 328I Sedan), 3 different temperature coolant temp profiles
• 234F = ECO mode (fuel economy)
• 221F = Normal mode
• 203F = High Load mode (lots of idling or sustained high rpm)

 

[Fatherof3]

Hi everyone. First time poster here. I have a 2021 ram 5.7 and the coolant temp on the digital readout started changing from when it was new.

I've done a number of searches on this forum and others and I have not been able to find any posts similar to mine.

For the first few thousand miles the coolant temp seem to operate like others have posted on this forum. Running with a low of about 203 degrees fahrenheit once warmed up to about 215 or 217 on the highway. A few months ago it started swinging quickly as soon as I accelerate. For example if it was running at about 206 as soon as you accelerate it would jump to 208 then 210 then 212 within a couple of seconds. After maintaining steady speed or decelerating the temperature would go back down to approximately 206. Sometimes it would drop to 199 and other times it would run up to 228 and then the fans would come on. Now all of a sudden when started when cold at ambient temp the coolant temperature starts shooting up right after cold start and gets to warm up temperature within a couple of minutes. For the first couple of thousand miles it did neither of these things.

The coolant level only dropped in the overflow tank a little bit since it was new. It now has about 8000 miles on it. Out of frustration I replaced the thermostat and purged all the air. This did not solve the problem. One thing that surprised me was the coolant changed smell to a terribly stinky sickly sweet smell, kind of like the old green coolant that has gotten real hot. I see no signs of a blown head gasket other than what I just listed. No apparent coolant in the oil and no smoke out of the exhaust. I have not seen or heard of a 5.7 hemi having head gasket problems. I like this truck and this is frustrating.
I did not take this to the dealer yet. I've had bad experiences before trying to get a problem repaired under warranty with Chevrolet. The bottom line is they didn't want to touch it until it was literally broken down and not running or flashing the check engine light with all kinds of codes. I know what it's like to come up against warranty. I'm pretty sure Dodge won't touch it until it's actually blowing coolant out of the radiator or so hot that it's obviously shouldn't be driven. So I'm trying to gain some experience with these 5th gen Ram pickups so I know if others have had this problem before I go to the dealer. I know this sounds like a head gasket. The pickup is so new that I'm not sure what to think. Has anybody else had or heard of this problem with a 5th generation Ram? I apologize for the long post. I hope I listed the pertinent details. Thank you.

Sounds to me like a temp sensor problem . Only because of you stating that the temp rises quicker now even at cool ambient temps when first started .

 

[Oldphart]

I have a feeling that most of us are used to looking at a standard temp gauge which uses a needle against a scale. Those type of gauges are notoriously over-damped and barely, if ever register a change during normal driving. The digital readout gives us real-time temp changes. It's not going crazy, just reporting it accurately.

 

[Gravel Roads]

Your range isn't unusual, but if you notice some crazy rapid stuff, maybe there could be something there, could even be the sensor itself.

On a side note, many modern vehicles have different coolant temp profile depending on the driving conditions, to maximize efficiency and performance. I haven't bothered to see if the RAM has special cooling profiles, but here is the one on my old BMW E90, just so you can see how varied the temps can be ...

For example, the BMW E90 (2007 328I Sedan), 3 different temperature coolant temp profiles
• 234F = ECO mode (fuel economy)
• 221F = Normal mode
• 203F = High Load mode (lots of idling or sustained high rpm)

Thank you for the information. Today when I drove it to work it got worse. It shot up to about normal operating temperature within a couple of minutes from an 86 degrees start. When I started my commute took a while for it to cool down from 215 degrees down to about 203 where it will normally run in the morning for a couple of minutes.

 

[knightro84]

Don't forget these trucks have the active grill shutters... for fuel economy purposes, the grill shutters stay closed during warm up to get the engine up to temp as quickly as possible. Before I had removed them, my truck was typically up to operating temp by the time I drove the mile or so to the entrance of my neighborhood. The active grill shutters will open/close while driving to keep fuel economy up and temps will fluctuate accordingly. As others have said, your temps and the fluctuations appear normal.

 

[Gravel Roads]

Your range isn't unusual, but if you notice some crazy rapid stuff, maybe there could be something there, could even be the sensor itself.

On a side note, many modern vehicles have different coolant temp profile depending on the driving conditions, to maximize efficiency and performance. I haven't bothered to see if the RAM has special cooling profiles, but here is the one on my old BMW E90, just so you can see how varied the temps can be ...

For example, the BMW E90 (2007 328I Sedan), 3 different temperature coolant temp profiles
• 234F = ECO mode (fuel economy)
• 221F = Normal mode
• 203F = High Load mode (lots of idling or sustained high rpm)

Thank you for the information. Today when I drove it to work it got worse. It shot up to about normal operating temperature within a couple of minutes from an 86 degrees start. When I started my commute took a while for it to cool down from 215 down to about 203 where it will normally run in the morning for a couple of minutes.

Your range isn't unusual, but if you notice some crazy rapid stuff, maybe there could be something there, could even be the sensor itself.

On a side note, many modern vehicles have different coolant temp profile depending on the driving conditions, to maximize efficiency and performance. I haven't bothered to see if the RAM has special cooling profiles, but here is the one on my old BMW E90, just so you can see how varied the temps can be ...

For example, the BMW E90 (2007 328I Sedan), 3 different temperature coolant temp profiles
• 234F = ECO mode (fuel economy)
• 221F = Normal mode
• 203F = High Load mode (lots of idling or sustained high rpm)

Thank you for the reply. Believe it or not this is my first forum of belonged to so I'm still trying to get the hang of it. This morning the situation got worse the temperature rocketed up to almost 146 degrees from about 86 degrees before I even got it out of my shop garage area. It then went to about 206 degrees which is normal then it went up to 215 and stayed there awhile. But what happens next is it starts to get really hot goes up to somewhere in the 220s and hangs there and then doesn't drop until you slow down. Sometimes it'll drop down to about 206 at that point. Then as soon as you accelerate within a few seconds it will go up to 215 or 217 or so and stay there. Then when you come to a stop it'll go up to about 228 and the fans will be running high speed and it will eventually drop down to about 217 once you start moving again. I wouldn't have known about any of this if I hadn't been watching the digital readout. The reason I began this post is because it acted totally different when it was new. It would vary between about 203 and 215 back and forth. The normal time it takes me to get out of my garage at this ambient temperature it would go up to about 120 degrees. It was usually a couple of minutes of a swing between 203 and 215 when it was new going down the freeway and I never noticed it shoot upwards as soon as I accelerate. The other surprise was when I changed thermostats the coolant smelled burned. I will probably take this somewhere and get a chemical block check done before I take it to the dealer. When I started this thread I was wondering if anyone else had these rapid temperature swings, and if this era Hemi was known for head gasket issues. Thank you.

 

[Gravel Roads]

Don't forget these trucks have the active grill shutters... for fuel economy purposes, the grill shutters stay closed during warm up to get the engine up to temp as quickly as possible. Before I had removed them, my truck was typically up to operating temp by the time I drove the mile or so to the entrance of my neighborhood. The active grill shutters will open/close while driving to keep fuel economy up and temps will fluctuate accordingly. As others have said, your temps and the fluctuations appear normal.

Yes. Im never see them closed when its sitting idling, other than when it does its self test at startup, (cold startup?) so they must only close at a certain speed (among other factors) so I will keep that in mind. Thank you.

 

[Hydroblueguy]

Hi everyone. First time poster here. I have a 2021 ram 5.7 and the coolant temp on the digital readout started changing from when it was new.

I've done a number of searches on this forum and others and I have not been able to find any posts similar to mine.

For the first few thousand miles the coolant temp seem to operate like others have posted on this forum. Running with a low of about 203 degrees fahrenheit once warmed up to about 215 or 217 on the highway. A few months ago it started swinging quickly as soon as I accelerate. For example if it was running at about 206 as soon as you accelerate it would jump to 208 then 210 then 212 within a couple of seconds. After maintaining steady speed or decelerating the temperature would go back down to approximately 206. Sometimes it would drop to 199 and other times it would run up to 228 and then the fans would come on. Now all of a sudden when started when cold at ambient temp the coolant temperature starts shooting up right after cold start and gets to warm up temperature within a couple of minutes. For the first couple of thousand miles it did neither of these things.

The coolant level only dropped in the overflow tank a little bit since it was new. It now has about 8000 miles on it. Out of frustration I replaced the thermostat and purged all the air. This did not solve the problem. One thing that surprised me was the coolant changed smell to a terribly stinky sickly sweet smell, kind of like the old green coolant that has gotten real hot. I see no signs of a blown head gasket other than what I just listed. No apparent coolant in the oil and no smoke out of the exhaust. I have not seen or heard of a 5.7 hemi having head gasket problems. I like this truck and this is frustrating.
I did not take this to the dealer yet. I've had bad experiences before trying to get a problem repaired under warranty with Chevrolet. The bottom line is they didn't want to touch it until it was literally broken down and not running or flashing the check engine light with all kinds of codes. I know what it's like to come up against warranty. I'm pretty sure Dodge won't touch it until it's actually blowing coolant out of the radiator or so hot that it's obviously shouldn't be driven. So I'm trying to gain some experience with these 5th gen Ram pickups so I know if others have had this problem before I go to the dealer. I know this sounds like a head gasket. The pickup is so new that I'm not sure what to think. Has anybody else had or heard of this problem with a 5th generation Ram? I apologize for the long post. I hope I listed the pertinent details. Thank you.

While under warranty you should have take to the dealer, now they will try to say you caused the problem! Also if you thought the Chevy dealers were bad for repairs, just wait till you go to the ram dealers Good luck!

 

[Gravel Roads]

While under warranty you should have take to the dealer, now they will try to say you caused the problem! Also if you thought the Chevy dealers were bad for repairs, just wait till you go to the ram dealers Good luck!

I know. That's another reason I defer to you guys before I take it in. But I will let everybody know what happens.

 

[Gravel Roads]

Your range isn't unusual, but if you notice some crazy rapid stuff, maybe there could be something there, could even be the sensor itself.

On a side note, many modern vehicles have different coolant temp profile depending on the driving conditions, to maximize efficiency and performance. I haven't bothered to see if the RAM has special cooling profiles, but here is the one on my old BMW E90, just so you can see how varied the temps can be ...

For example, the BMW E90 (2007 328I Sedan), 3 different temperature coolant temp profiles
• 234F = ECO mode (fuel economy)
• 221F = Normal mode
• 203F = High Load mode (lots of idling or sustained high rpm)

Thank you for the information. The good news is, it's 105 degrees out and so I'll be running the AC at max. That seems to keep the fans on and it actually sometimes runs cooler.

 

[HemiDude]

One thing I didn't see in your posts... what do the other fluid readouts say? Oil temp, trans temp? If you are truly running hot, these are likely going to rise right along with your coolant temp. If they stay in their respective "normal" ranges, you probably have an electonic malfunction in the coolant circuit

 

[Gravel Roads]

One thing I didn't see in your posts... what do the other fluid readouts say? Oil temp, trans temp? If you are truly running hot, these are likely going to rise right along with your coolant temp. If they stay in their respective "normal" ranges, you probably have an electonic malfunction in the coolant circuit

The oil temp runs about 10 degrees hotter than coolant temp until the coolant temp gets hot say 226 degrees then the oil temp starts to follow coolant temp and then will max out a little higher until the vehicle cools down. Trans temp almost always runs about 181 to 185. It's been a little bit more noticeable lately since I haven't been using AC and so the fans haven't run as much. I have noticed it goes from ambient temp to warmed up thermostat opening temp within about 5 or 6 minutes. This morning pulling out of my garage it went from 78 degrees to 147 degrees in a minute or two. Watching my digital readout it seems to gain about a degree or second for a while during warm-up. In total it was around six and a half minutes to when the thermostat opened. My commute is always the same. The thermostat would always open right at my off ramp in the morning. Now it opens up a little bit earlier. Thinking about buying a block check device to check for combustion in the coolant because it smells so burned. As for today the temperature would run between 204 and 221 and when you get to a stop it would come up to 228 and then the fans would turn on to pull it down to about 219 and then repeat. I suppose it could be the thermostat even though I replaced it with a brand new Mopar unit but likely the thermostats okay. I'm shaking my head. Have you happened to notice how quickly your engine comes up to temperature?

 

[HemiDude]

I haven't lately. I will watch it in the few days and let you know what I see

 

[Gravel Roads]

I haven't lately. I will watch it in the few days and let you know what I see.

I haven't lately. I will watch it in the few days and let you know what I see

Thank you.