High Coolant temps

[Tedmeister]

Last couple of days I have noticed that my coolant temps have really jumped in stop and go traffic. Normal temps are in 200 to 210 range.
Temps hit a high of 240 while I was sitting in traffic. As soon as I started moving it dropped to 215. Then during slow down and waiting
temps jumped again. As long as I am driving the temps stay in the normal range. No codes. What should I start with.
Truck has 180k miles. Engine was replaced two and a half years ago at 120K miles, with a Jasper re-man. I bought the installation kit, which came with a new water pump.

 

[Ken226]

Last couple of days I have noticed that my coolant temps have really jumped in stop and go traffic. Normal temps are in 200 to 210 range.
Temps hit a high of 240 while I was sitting in traffic. As soon as I started moving it dropped to 215. Then during slow down and waiting
temps jumped again. As long as I am driving the temps stay in the normal range. No codes. What should I start with.
Truck has 180k miles. Engine was replaced two and a half years ago at 120K miles, with a Jasper re-man. I bought the installation kit, which came with a new water pump.

Check your clutch fan.

Check out a few YouTube videos on the subject, as there are a few ways to test it

 

[wrench78]

Check your overflow tank to make sure you have coolant in there. Also look for leaks. Sounds like you might have an air pocket in your system. I had the same issue a few months ago. My water pump was going bad and leaking.

 

[jws123]

Just keep in mind if you keep hitting 240f Your going to blow the engine so whatever your issue is dont wait to fix it. as mentioned above clutch fan,leaks,water pump ECT ECT.

 

[62Blazer]

My first suspicion with those symptoms would be the cooling fan. The primary purpose of the fan is to blow air through the radiator when the truck is stopped or going real slow. When driving down the road at 50+ mph you naturally have high air flow going through the radiator and the fan doesn't turn on much.

 

[wrench78]

My first suspicion with those symptoms would be the cooling fan. The primary purpose of the fan is to blow air through the radiator when the truck is stopped or going real slow. When driving down the road at 50+ mph you naturally have high air flow going through the radiator and the fan doesn't turn on much.

Actually, the fan pulls outside air in through the radiator towards the engine.

 

[Tedmeister]

I added less than a quart to the radiator, but then used the rest of the gallon to fill the overflow tank.
Temps are still odd. Doesn't matter if I'm stopped or moving at 60 mph, the temps cycle from
210 or 212 up to 217 or 219. It is a slow up and down between those temps.
It is going in to be looked at by a mechanic. Good time to get my exhaust leak taken care of as well. I'll
post remedies when I get the truck back.

 

[Wild one]

I added less than a quart to the radiator, but then used the rest of the gallon to fill the overflow tank.
Temps are still odd. Doesn't matter if I'm stopped or moving at 60 mph, the temps cycle from
210 or 212 up to 217 or 219. It is a slow up and down between those temps.
It is going in to be looked at by a mechanic. Good time to get my exhaust leak taken care of as well. I'll
post remedies when I get the truck back.

Sounds like a bad thermostat.The days of a thermostat lasting 10 years are long gone,now if you get a year or 2 out of one,go buy a lottery ticket.It's not uncommon for a new thermostat to die with-in a couple months of install.
Always check a new thermostat before install,by chucking it in a pot of water on the stove,and using a meat thermometer to monitor the temp of the water when it starts to open.

 

[Tedmeister]

We did replace the thermostat and it has solved the problem. I also got rid of the gas cap icon on
the dash and check engine light by replacing the leak detection pump or "ESIM".

 

[TJP440]

thanks for the update