Coolant temp fluctuations

[Hoeoperator320]

I've been getting some weird temp fluctuations lately and I'm not sure what to think. My truck is a 2012 with 77k on it. Did the e-fan swap and 180°thermostat a few years ago and it's been great. The temps stayed steady between 178 and 203 at the max. I've had this truck in the mountains in -20° to the desert in 120°. Driven over many mountain passes hard too. Temps always stayed steady.
I started smelling coolant in the cab a few weeks ago. Well I knew that meant heater core. A short while later the temps started fluctuating a little more then normal. Not overheating but getting up closer to 190 sometimes. I just figured the coolant was getting low because of the leak and topped it off. Wasn't very low. Finally did the heater core last weekend. It was definitely leaking. Replaced the evaporator and blend doors at the same time also. I went threw the whole process and flushed out the old coolant. Drove it a bunch and the fluctuations continued. It even spiked a couple times up to 220. It seemed random. Driving. If I let it sit and the fan kicked on the temps would drop, usually down to about 181.
I figured the thermostat was messed up so I ordered a new one from Moe's. Came fast and I swapped it in Friday. Well that seemed to make a difference. Tempts stayed low. Would hover between 176 and 183 in the driveway and around town. I thought that did it. Decided to take it out for a run up threw the mountains last night. Seemed good until I started climbing the pass. Outside temp was about 77°. I was driving somewhat hard, maybe 70-80mph . Temps climbed the whole way. When I got to the top it was at 206. Coming down it immediately dropped to 177. This seems like a massive swing in temps to me. Driving around in the woods it would stay low on level ground but any time I would start climbing a hill the temps would go up. Not overheating but higher then normal. Coming home, the other side of the pass isn't as steep and the temps didn't go up much at all. I don't really understand what's going on. I know this isn't hot for these trucks but something definitely changed. And I don't know what it will do if I'm offroad out in the desert in some real heat. I have a new factory radiator cap coming but I don't think that really has anything to do with it. I think I'll replace the temp sensor next because it's easy. My truck doesn't have the shutters in the grill. Only thing i can think of would be something with the radiator or waterpump but no sure how. The swings in temp are weird to me. If it did this from the beginning then I wouldn't think much of it but it was so steady in the past that this makes me think something is wrong. Anyone have any similar experience or ideas? Oil and coolant both looked good.

 

[Burla]

Get some rmi-25, especially since had a clogged or leaking heater core, o2 doesnt make nice with coolants. You pressure wash rad fins? Only use oem ram coolant all this time, every time you cracked it open? You have 50/50 coolant mix as well?

 

[Burla]

206f is nothing when climbing a hill 80mph, I'd expect higher, not sure there is an issue. Once your oil hits 220f and its warm outside under load, I wouldnt not expect the 203f to the max like it used to me regardless. Check oil temps next time, they were probably 250f, and the block was just hot. Plus idle down slowly as well, gasoline heads werent meant to get that hot. The oil temp is the issue I believe, once that gets super hot, through out the norm on coolant temps.

 

[Burla]

And btw no real way to fix that besides after market oil cooling systems, the bottom line warm ambiant temps under load up a hill, stuff is just gonna get hot generally speaking. And yes stopp working it and coolant will come down as well super fast compared to the oil which stays hot much longer. Next time note oil temps.

BTW, what you do in real heat is idle down truck at 260f oil temps, or you will be stranded.

 

[Hoeoperator320]

I flushed it with about 15 gallons of distilled water last Saturday. Used 9 quarts of zerex go5 coolant and distilled water to refill . Bought the truck with 21k on it so I've put about 56k on it myself. Second time I've changed the coolant. I didn't use any other additives or flushes. Haven't cleaned the fins in a while so I'll do that. I know the temps aren't that high, it's the sudden increase in fluctuation that concerned me. Randomly getting hotter in 70°weather in my neighborhood then it did exploring the desert around Havasu. I'll keep an eye on my oil temp. My tranny was between 130-160 depending. It has a bigger pan on it. That seemed normal so I think air is at least getting threw that cooler.

 

[Burla]

That coolant is one of the best so your good there. Coolant just dissipates temp especially when you change the load. For what it's worth, I dont see any issue.

 

[Hoeoperator320]

Well I ordered some of that rmi-25. I'll give that a try , clean the rad fins and just monitor it. I want to see what it does in 100° weather. Thank you for the replies

 

[Burla]

Well I ordered some of that rmi-25. I'll give that a try , clean the rad fins and just monitor it. I want to see what it does in 100° weather. Thank you for the replies

I've used rmi25 a lot, it will dislodge any slime and put it in overflow tank, if overflow tank is clean after 500 miles, your system was clean in the first place, that also happens all the time with this product, sometimes it isnt needed, but if there is any issues they end up in over flow tank were you need to vacuum them out. Even if your system is good, rmi25 still has other benefits, look them up on their page.

 

[CalDad14]

Hello. I feel like I'm getting fluctuations kind of like you're describing. What's you're set up? Mine is a 17' 1500, 4×4, 392 gears. Bought brand new at 160kms. Coming up on 40,000kms now. First 6.5yrs, never saw the coolant or oil temp above 96°C - 97°C(204°F - 206°F). No matter how cold or hot outside, towing in summer, the coolant and oil temp were always within a couple degrees.

Mid March I started seeing coolant fluctuations(4 - 10 degrees) for no reason whatsoever. Driving flat, under 50 mph, not stop and go, cool weather, my coolant temp would climb, then drop. I feel like it coinsided w/a fan that sounds like is running way more often than it should be, seperate from rad fan.

Now summertime w/hotter temps, my coolant temps still yo-yo between 94°C(201°F) and 100°C(212°F), but my oil temp is running higher than ever, 98°C(208°F) - 100°C(212°F).

We did our first trip this summer(in said Ram!), 2hr drive to the lake. My coolant did it's yo-yo thing, oil temp got as high as 104°C(219°F), even when the coolant temp was around 96°C(204°F), also my trans temp was fluctuating(only few degrees) kind of like the coolant, not normal. Was not pushing the truck hard. Maybe hit 80mph to pass, but cruise around 70mph. Highway speed limit here is 110km/h(68mph).

Had a new thermostat installed two weeks ago, but didn't make a difference. Have brand new oil & filter.

I'm with you. I understand the temps I'm seeing are w/in the safe specs, but it's not normal for my truck. I just can't shake the feeling something is up. Kind of feel like I'm sitting on a time bomb. Scared to go camping in the bush. Here in Alberta you can run through mountain passes where there is no cell service. I'm actually comparing/searching/studying up for an emergency assist device(Inreach), just in case. Have lost some confidence in my Ram, and it makes me sad.

I honestly feel that there is something up with the low speed fan that I hear running nearly all the time, and the oil temp sensor or oil pressure sensor that is making the cooling/heating system work harder. But w/out the check engine light, there's nothing really that can be done. I did think of cleaning fins like you mentioned, also Rmi25. But I battle some physical disabilities, between that, the pain that I deal with everyday, just keeping up w/my 8yr old twins is hard enough!

Again, I've towed 5,000lbs w/the truck maxed out on it's payload, family of four in the truck, AC on, middle of summer with 35°C(95°F) heat, pulling a hill w/a cross wind and the coolant temp never broke 97°C(206°F), the oil temp never went higher than 96°C(204°F). And for the life of this truck the coolant and oil temp have always, always run w/in 2°C of eachother.

I don't buy that, this is just the "new normal" of our truck.

I started a post in the 4th gen, general section, "Gremlins in the Radiator"! Anything anyone can add would be great.

Keep us posted on what you discover...

Sleepless in Alberta!

 

[Hoeoperator320]

Interesting, sounds pretty similar to mine. I did search a bunch of old posts/ other forums when this started. I noticed some people had temperature swings and considered it normal, and other people said their truck always stayed within a few degrees. Seemed to be one or the other. I also saw a lot of posts about how bad thermostat quality has gotten. I definitely saw a difference when I changed mine last weekend. So far this week my temps have stay low. 174°F-183°F. But it's been cool and rainy so far. This weekend will be hot and I'm thinking about heading over the mountain to the desert. That will test it. My oil temps have stayed pretty close to the coolant temps. Under 180 so far.
I understand your hesitancy to now take the truck into the backcountry. That's my biggest stress too. I'm often well outside cell service. If something happens out there you can be in a bad situation pretty quick. I'll check out your other thread and continue to update this.

 

[grizzstang]

Hello. I feel like I'm getting fluctuations kind of like you're describing. What's you're set up? Mine is a 17' 1500, 4×4, 392 gears. Bought brand new at 160kms. Coming up on 40,000kms now. First 6.5yrs, never saw the coolant or oil temp above 96°C - 97°C(204°F - 206°F). No matter how cold or hot outside, towing in summer, the coolant and oil temp were always within a couple degrees.

Mid March I started seeing coolant fluctuations(4 - 10 degrees) for no reason whatsoever. Driving flat, under 50 mph, not stop and go, cool weather, my coolant temp would climb, then drop. I feel like it coinsided w/a fan that sounds like is running way more often than it should be, seperate from rad fan.

Now summertime w/hotter temps, my coolant temps still yo-yo between 94°C(201°F) and 100°C(212°F), but my oil temp is running higher than ever, 98°C(208°F) - 100°C(212°F).

We did our first trip this summer(in said Ram!), 2hr drive to the lake. My coolant did it's yo-yo thing, oil temp got as high as 104°C(219°F), even when the coolant temp was around 96°C(204°F), also my trans temp was fluctuating(only few degrees) kind of like the coolant, not normal. Was not pushing the truck hard. Maybe hit 80mph to pass, but cruise around 70mph. Highway speed limit here is 110km/h(68mph).

Had a new thermostat installed two weeks ago, but didn't make a difference. Have brand new oil & filter.

I'm with you. I understand the temps I'm seeing are w/in the safe specs, but it's not normal for my truck. I just can't shake the feeling something is up. Kind of feel like I'm sitting on a time bomb. Scared to go camping in the bush. Here in Alberta you can run through mountain passes where there is no cell service. I'm actually comparing/searching/studying up for an emergency assist device(Inreach), just in case. Have lost some confidence in my Ram, and it makes me sad.

I honestly feel that there is something up with the low speed fan that I hear running nearly all the time, and the oil temp sensor or oil pressure sensor that is making the cooling/heating system work harder. But w/out the check engine light, there's nothing really that can be done. I did think of cleaning fins like you mentioned, also Rmi25. But I battle some physical disabilities, between that, the pain that I deal with everyday, just keeping up w/my 8yr old twins is hard enough!

Again, I've towed 5,000lbs w/the truck maxed out on it's payload, family of four in the truck, AC on, middle of summer with 35°C(95°F) heat, pulling a hill w/a cross wind and the coolant temp never broke 97°C(206°F), the oil temp never went higher than 96°C(204°F). And for the life of this truck the coolant and oil temp have always, always run w/in 2°C of eachother.

I don't buy that, this is just the "new normal" of our truck.

I started a post in the 4th gen, general section, "Gremlins in the Radiator"! Anything anyone can add would be great.

Keep us posted on what you discover...

Sleepless in Alberta!

First you don't have any low speed fan. You have a mechanical fan and an electric fan.

The electric fan comes on when the AC is on or when your truck gets to a certain temp.

Your mechanical fan will always be spinning slightly and the fan clutch will engage to spin it faster when it is warmer.

Check to see if your truck has AGS (Active Grill Shutters) in front of your rad. I found that they stay closed a lot more than I liked even in our cooler temps. They close at a certain speed to make the truck more aerodynamic and supposedly save on fuel. I don't feel like they saved any fuel but they do make your truck run hotter. You can remove all but the top and bottom shutters to allow for better airflow through your rad and it won't set any codes. I have not seen any negative effects from doing this, even in the dead of winter but it does allow my truck to run cooler in the summer. Do a search on how to remove them. It is pretty easy and worth it IMO.

 

[Bam930878]

So you did a e fan swap and 180 thermostat did you have it tuned to have the fan come on at lower temp as well and how does your heat work in the cold ive always been told the 180 was a little low when i did mine i went with what the 3rd gen had 192

 

[Hoeoperator320]

Yes it's tuned to come on. Heat works great. Have taken this truck ice fishing in -20°. Never had trouble keeping me warm.

 

[Bam930878]

Check of you have active grill shutters and do you recall what temp the fan was reprogramed to