Water pump

NoBusKing911

I have 02 Durango with the 4.7. The radiator blew up on me while driving the other day. Apparently it was overheating but due to an electrical issue and the no bus code my gauges will occasionally not work so I couldn’t tell. But that’s a another story for another day. I have another truck identical to this one. I swapped out the radiators and fired it up, let get to normal operating temp. Took it for a drive and it started to overheat again. Which leads me to this question, would this be signs of a bad water pump?

Mr_Shiftright

Overheating can be tricky to diagnose, since there are so many different components involved. You could have water pump problems, but unless the pump is leaking, the only possibility there is a broken impeller in the pump itself---a rare occurrence to say the least. You'd have to gauge, once the thermostat is opened, if water is indeed circulating around the top of the radiator (with cap off, you can look in and see the "currents" of coolant). If the water is churning in there, then the pump is good.

You could have issues with the electrical cooling fans not kicking in on time, or failing to work at all. This is usually seen as a low speed, or idling overheat. If the truck only overheats at freeway speeds, or driving around town at moderate speeds, then it could be a circulation problem--like a stuck thermostat.

you could also have a bad head gasket--not out of the question on a 16 year old car. And no, you don't need to see water in the oil for this to be diagnosed. The head gasket leak could be from the combustion chamber only to a coolant galley, not an oil galley. You can test the coolant for combustion gases using a chemical kit you can buy at Autozone or some such place. You can also test by pressurizing the coolant system, and while it is still under pressure, extracting a spark plug or two or six, and looking for coolant on the tip.

Most head gasket failures result in a pretty fast overheat.

NoBusKing911

I’m pretty sure I’m getting circulation, as I was filling the radiator I had the bleeder valve open and as it got full it would start pushing fluid out of the bleeder plug. The rad fan works just fine. I’m hoping it’s a stuck thermostat, haven’t checked that yet. I hope it’s not a bad head gasket. I have an identical truck for parts so swaping motors would be an option if a head gasket is bad. The doner truck I ran for about a year but couldn’t pass inspection due to computer problems and check engine light wouldn’t clear, even after a new computer was put in, it ran very well the time I had it on the road.

Thanks bud, I appreciate the help.