Truck went back to the dealer for a TSB, they replaced the water pump. Truck was still overheating. Replaced fan clutch (2x now), Temp sensor, thermostat (once after market, once direct from dealer), and flushed (with running water) the radiator, engine, heater core hoses to the cab. After all that, the truck is still constantly, yet randomly overheating. It will work normal for a few hours and than start to creep up to 230. Let it sit, might instantly overheat again (removed cap, let air out to cool, check fluid level each time). Sometimes spiking as high as 260. The fan never seems to sound "like a jet engine" as I've heard on these forums, but I can't stop or slow the fan with a newspaper either, so it seems to be spinning with resistance. At this point, I'm not sure what the problem is, or could be. Is there any other common causes or diagnostics methods? anything obvious i missed?

 

Where did you get the fan clutches?...What brand?...Here is a recent thread concerning overheating on older trucks which will still apply to later models...Welcome to DTR......Ben

 

Both fan clutches came direct from the dealer

 

Unless some of the new parts are bad, it seems that the radiator may be plugged. A garden hose will not clear out a clogged radiator, they have to have something much stronger. Does the rig heat up real fast or is it kind of a slow process of it inching up? My experience has been that when radiators start to lose capacity because it is clogging by degrees, the temp slowly rises. This, as opposed to a failure of the water pump or no coolant, will heat up real fast. Has it ever been run with just water in it? (I doubt this)...Mark

 

Definitely never run it with straight water, we've gone through gallons on gallons of the pink mopar stuff at this point. It is most definitly a slow creep in temp, usually. Once it hits that 215 point though, it can quickly his 230. But generally we'll be there 190....5 mins later...194....next ed light creeps up to 200...than next light, might go like 200-220

 

It still sounds like your radiator may still be cruded up. I had an MC that did the same. After throwing some parts at it, it turned out to be the radiator was full of crud. My 90' Cummins did the same thing, so I took it to my favorite local radiator shop that I had used for years and he told me that he couldn't rod it out and that if he recored it with the material he had, it would have diminished the capacity. So I ended up buying a new radiator...Mark