Hi, I need some help diagnosing or at least get pointed in the right direction on an issue with my 2006 1500 Ram (5.7L). Was riding home today, last 15 minutes of a 90 minute drive, on the highway with the AC going, I didn't realize my temp. gauge creeping up until the light came on, at which point I turned the AC off and cranked the heat, temp quickly came right down to a little above the halfway mark. I was able to get her home, as soon as I shut the engine down, i had coolant pouring out everywhere, couldnt pinpoint exactly where because it was spraying so much. There are no obvious blown hoses or anything, and I still cant tell where it is leaking from. I still have fluid in the reservoir, so I ran it for a second to see where it was leaking from and does not appear to be leaking anymore...kind of stumped. Anyone else ever have a similar issue?

 

Thermostat may have failed. You may want to try a fail-safe (fail-open) thermostat next. I"d also recommend replacing the coolant and both hoses while you are at it.

 

Turning the A/C off didn't help any. None of its heat is dumped into the coolant. Bad 'stat sounds like a good first guess. You should have left it running and sprayed the radiator with a garden hose for a few minutes.

I've not had much luck finding fail-open 'stats. I know they exist, but no one wants to sell them.

 

Ok, thanks. Would a failed thermostat explain the coolant spraying out once I shut it off? It now looks like it may be dripping from the water pump, so I think the pump may have failed.

 

Yep, a failed thermostat could result in the problems you described. You should replace it before driving the truck again. Your water pump may not be bad and I think you should watch it for a while before replacing it. Keep an eye on your radiator and overflow tank levels, and also for puddles of coolant on the ground.

 

The spraying came from the pressure spike when you shut it off. Once the motor's off, there's no cooling, so the heat and pressure go up.

 

Ok, this helps alot, thanks again.

 

Ended up being the water pump, just noticed the shaft is loose and appears that's where the coolant was leaking from, a little easier to see now that all the excess coolant has dried. I changed out the thermostat this morning and went to top off the radiator and it started pouring out of the fan housing where the shaft penetrates.

 

Glad you found the problem so quickly. While it has been suggested that you replace the hoses, it is just as important to change the oil, especially if it's regular dino. Since the belt is six years old, it makes sense to change it now while you have it off.