Hi everyone, I'm new to this site. I've owned a 2003 Durango 5.9l 4wd for about 5 years now, and it's been great. A few weeks ago I noticed a small bit of water on the pavement underneath it, and wrote it off as water from the AC condenser. About a week ago the "check gauges" dash light came on and a bell rang, and I noticed the temp was nearly maxed out. As I was pulling over, it dropped to normal, then shot back up, down, up. I discovered the y hose on the passenger side was broken. Towed it home, replaced the hose, filled the radiator, and after heating up it did the same thing. Replaced the thermostat, same thing. Ran it with the radiator cap off (it's not on the radiator but on the top hose going into the thermostat housing), revved the engine and I could see the water being pulled down(but apparently not flowing completely through the system, because the heater would blow cold air after a few minutes yet the hoses were boiling hot), so I believe the water pump is ok. No water is leaking, BUT both sides of the radiator will get extremely hot (mainly the driver's side) but the radiator grill itself is completely ice cold. Does anyone know if this is an indication of a plugged radiator? The oil is clear, and the water remains full. I'm not a mechanic, the few things I've deduced or repaired so far is from past experience and not from any real knowledge about car repair. I was told that I could put borax into the water and it might loosen up any corrosion plugs. I was also thinking that possibly a piece of hard plastic from the "Y" connector (it has a thin connector that the rubber hose slides on to) might have plugged the radiator. I'm just trying to figure out where to go from here, and the coolness of the radiator grill, while boiling hot on the sides, just seems a bit odd to me.

 

If indeed it is a plugged radiator then the best thing you can do is just replace it. Putting chemicals into it may help loosen it and "band aid" it now but, its also going to do damage that will lead to to replacement later anyways. Fix it right the first time and forget about it.

 

Thanks for the response! My main concern was whether or not the radiator was actually clogged to begin with, and how to tell for sure that it is before I replace it. I could probably replace it myself if that's definitely the problem, but I just wanted to be sure. I thought there might be some way to test it, or something that a mechanic might do to verify that the radiator is definitely clogged.

 

Get a temp gun (Harbor Freight usually has them for around $20) measure the temp in several places throughout the radiator.. You should be getting a pretty uniform temp across the whole thing.. If you run into an area that is much hotter than everywhere else you have a "hot spot" and 99.9% of the time that is where the clog or trouble is..

 

if the radiator itself is staying nice and cool there is a blockage somewhere, however since you said the heat is also blowing cold it is possible you have air in a line somewhere causing problems.

it is also possible that the new t-stat is bad, if you want to confirm this is not the problem simply pull it out and run the truck, see if the radiator gets hot (as designed) and the heat blows hot, if so your stat is not opening and needs to be replaced.

you can also diagnose a bad t-stat in a pot of boiling water to where it opens up

 

Actually it does blow heat-for a few minutes, then it's cool air. I was thinking maybe the water not circulating is causing the standing water in the heater core to eventually cool from the fan. I guess the same is also possible with the radiator though, since the engine fan is constantly blowing on, but there's never any heat from it like there is from the heater core so a blockage seemed feasible to me. I never thought about removing the thermostat duh, that would definitely be an easy and suspect thing to check. I'll post updates as I work to fix this in case it someone else has the same problem in the future. Got a hernia last week cutting and carrying firewood so it'll be as I can get around to messing with it. Always something lol.