I have a problem with my colloing system on an 02 Ram 1500 4x4. The temperature gauge was typically right in the middle but a week ago it started rising. Afer about 10 miles it would get close to the hot line so I would shut it down before it would get any hotter. I replaced my thermostat but the same thing would happen. I ncould get to work which is about 15 miles away in the morning and it was okay. Coming home in the afternoon I couldn't make it all the way home without having to pull over and letting it cool down first. On a reccomnedation from a friend I just changed the fan clutch and nothing changed. I can let it idle in the driveway all day long and it won't get hot. Does anyone have any ideas or suggestions?

 

When it overheats is the lower radiator hose hot? You could have a problem with the water pump.

 

check your radiator cap,if your thernostat had failed, they are designed to fail open. That would just cause it to take longer to warm up. If you radiator cap is bad, wont hold enough pressure. It is usually the weak link in a cooling system.

 

something is wrong, when you drive the truck it will want to overheat but just letting it sit in the drive way idling it wont get hot? i cant understand that.

 

thats because when at idle, the cap is holding enough pressure to compensate, but the temp rises as does the pressure at driving speeds, and the cap wont handle it.. You raise the boiling point of the water 3 degrees per pound of pressure, so 15 psi raises the boiling point above the antifreeze adjusted temp by 45 degrees. thats why i figure it could be the cap.

 

Try the radiator cap first, seeing that I had the same problem with my project jeep. Would be fine until I took it out driving, loss of pressure in the system. Of course, that was after I had already replaced the water pump. So, try that first, its cheaper.

 

Do a flush of the cooling system and change the anti-freeze. I doubt that the pump is bad this early in the game. More likely, you have a build up of sludge in the bottom of the radiator causing a lack of flow/tube blockage. You can easily verify this by using an infared temp gun to look at the individual passagesof the radiator as the systemheats up. Another thing you can do is start up the engine cold with the radiator cap off, leaving it at idle to heat up, as the thermostat opens, you should see flow through the top of the radiator, increase engine rpm's slowly, you should see increased flow across the top of the rad. it also might be a good idea to drain some of the fluid down to the middle of the top radiator tank so you don't get coolant spilling all over as the heat comes up.
I'm a BIG fan of changing the fluid every three years, even though the coolant is supposed to last much longer than that. Often times the coolant starts turning acidic and begins eating away the aluminum causing even worse problems, such as heater core failure-----we've all seen how much that can cost or how much time it can consume to repair here on the forum
A simply fluid change with a good chemical flush can prevent an awful lot of work and money expediture long term.

 

A good coolant flush could and will always help but is a ways away, in my opinion, from the present problem. Like FFMedic and i have said, sounds like the cap. Autozone maybe able check it for you. It is usually the weak link, and the easiest to check. So check that first, but gone fishin is right, you may consider a coolant flush afterwards. 3 yrs is about the right time. Hope this helps

 

For some reason... did you happen to add coolant to your system? if so... was it of a different color? is so... that could be your problem....

 

I would also just try a flush and cap first, about the cheapest thing you can do.

I am not sure about the Ram, but some vehicles also require you to bleed the coolant system of air. If it does require this you will see "bleeder screws" near the t-stat housing or somewhere along the upper hose. Open the bleeder with the engine running and hot, keep open until only coolant comes out.