Hi all, I hope to be on here a lot as I start working on my "new to me" 1998 Durango. It's a 4x4 5.2L v8 Auto and the previous owner let it go to me pretty cheap (it's in great shape, 188k miles, interior is nice, engine's strong, no rattles, everything seems tight and works as it should) cause it's overheating. He said he changed the thermostat and water pump to no avail but in the process he said he found out that he's pretty sure the radiator is plugged up due to some previous owner using stop leak type stuff. He went out and bought a replacement from the local wrecking yard and included that with the truck when I picked it up. I' just starting out so I'm wondering if you guys already have a method or order of things to check to diagnose what's causing the overheating instead of just blindly swapping parts.....(plus I can't really assume that even if they were changed, that the thermo or pump are installed or working correctly. Any advice would be appreciated.

To be more specific about how it overheats. I picked it up about an hour away. I drove 60mph down the mostly level highway for 30min and the temp sloooooowly rose to just a bit below halfway. Parked it and had lunch. Then got in and the next 30min is a 3500ft elevation climb on backroads up to my house. that's when the real trouble began. It quickly started rising and eventually I had to pull over, let it cool and add water as i was bubbling out the drain all over the place. Had to do that a few times on the way up. Seems if i stayed at below 1400rpm it would remain steady. at 1400-1600 it goes up really slow, at 2000rpm it goes up fast and overheats in a matter of a few minutes.

 

it sounds like the cooling capacity is diminished on the engine, not completely gone. That could very easily point to a partially open t-stat (not open all the way but enough to keep you ok at cruising speeds), a weak water pump, or a blockage in the system restricting flow.

you can check the radiator for hot spots with a laser temp gun, or go to your local fire dept and ask if they have a FLIR(or other IR/Heat sensing) camera they would like to show you, have them point it at the radiator with the hood open while its hot, this should nicely show the temperature gradient and confirm if the radiator is in fact the culprit.

 

Thanks for the info. Yeah I do have a laser temp gun. I watched some youtube videos last night on possible overheating causes. Just seemed like everything from the t-stat to the radiator cap and everything in between could cause it. I ruled out a headgasket based on clean oil. I ruled out the fan due to the fact it overheats at speed. After seeing how much of a pain it is to just get to the t-stat and how much I'm gonna be into it to replace the radiator I decided just to give the cooling system an overhaul. Picked up a new t-stat, t-stat tube, waterpump, radiator cap and already have the replacement radiator so gonna go for broke tonight and just replace everything and cross my fingers that the problem is gone when I'm done. If it's not then not sure what else to try. Hopefully I'll know in the next few hours....

 

If it doesn't completely go away you're not the only one. Mine will run a little hot on the highway in the summertime but not dangerous, just around 210 with a 180 t stat. Nothing wrong with 210 though. It will climb in the city. Truck got t stat, water pump, both hoses, radiator, t stat housing all replaced. Still does it. It's one of two things now. Either my clutch fan doesn't pull enough air at idle or my new radiator is junk. It's single row, and factory is double row if you have a tow package like I do. But it's a project truck. I deal with it for now. Eventually I'll stuff a big aluminum griffin radiator in there and put my big electric fan back in. Should be good to go then.

 

Well, changed out the t-stat, radiator, radiator cap, water pump and put in the salvaged radiator and problem appears to be solved. I'm almost certain it was all due to someone putting too much of that leak stop stuff to stop some unknown leak and it eventually started coming off and plugging up the radiator cause it had a lot of junk in it and still does. I'm keeping it and need to look up good ways of getting all that crud out as it's nicer than the salvage one I just put in. Haven't driven it much yet (just let it idle for a long time till i was sure the temp was up to operating and it didn't continue to climb. It settled at around 190-195 which is what the t-stat is I believe so perfect there. Went for a quick drive around the block (about 5 miles or so a little heavy on the throttle and no issues. Gonna go down to town today or tomorrow and that's a good steep climb on the way back so that should tell me for sure how it's running. It also had an irritating pully/belt noise so I replaced the idler pulley and the belt and that noise went away completely. So now down to a few issues left I need to work through but I'll start new threads for those. front HVAC vents that don't blow (I can hear the diverter moving but the air doesn't come out) and a weird one, the indicator for the gears on the tranny is off so it shows nothing when in R, shows R when in N, N when in D....etc. I'm hoping that's just an adjustment thing...

 

Glad to hear it. Continue to pay attention to it once it gets hot this summer to make sure the problem bis in fact completely solved, but it sounds like you're good. The gear selector issue is a simple adjustment on the steering column. Find the little cable and at the end of it on the column side theres a little plastic twist nut that adjusts it.

 

Yeah I drove it down to town yesterday. That's a 40 mile one-way trip. 20 miles down a mountain and 20 miles on flat. it did perfect heat wise except i did notice it getting warmer (about 210) while sitting idling for a long time at the drive thru. Soon as we started moving, it popped back down to 195ish which is were it stayed the entire trip down and back up the 3000' elevation climb. So If I'm reading that right that probably means a fan clutch is starting to go out? I know I still have air in the system, haven't been able to purge it all out and I can hear it gurgling when the car starts. I also noticed a small leak in the salvage radiator I put in. It's really small (like a drop every once in a while but it's there and I'm assuming will allow air back in the system so I either need to figure out how to clean the old radiator of the stop leak or just buy a new one online.

Got the gear indicator mostly fixed but the **** adjustment is maxed out and it's still not perfect but at least you can tell which gear you're in.

If anyone has any suggestions on a good radiator and fan to replace mine with I'm all ears. I prefer to have more cooling and not need it, especially since I hope to use the durango to haul a 16' flatbed trailer with 2K lbs of lumber up my hill occasionally so I'll be using whatever cooling the truck can muster. Today I haul our little trash trailer up and down the hill so that'll add a little more stress than yesterday and I'll keep an eye on it.

 

once the stop leak goes into the radiator is in, there is no getting it out, just spring for a new radiator if the salvaged one is leaking, they are not excessively expensive and are worth the peace of mind IMO.

Also keep an eye on the overflow, the 5.2 and 5.9 are self burping systems as long as you keep that overflow topped off the air will work its way out and you will eventually be fine.

as for the clutch fan, the best cooling you can get is a replacement clutch, most recommend the standard duty as the heavy duty clutch will engage much more frequently and that fan is LOUD and draining when the clutch engages.

 

I've noticed the same thing with mine since I've owned it. Glad I'm not the only one. Takes a long time to warm up and if it's really cold outside the engine never gets warm enough to have really good heat in the cab. It's okay, but not great. When you're sitting at idle it's not pulling as much air through the radiator so the temp will climb a bit but once that thermostat fully opens it will stop climbing if your system is okay. The coolant temp sensors in these trucks are very sensitive, or the computer, and the result is you can literally see a 5 degree difference in temperature on your factory gauges. Most modern vehicles are not like that. I guess it gives people peace of mind to never see that temp needle move.

You may still need a new clutch, i don't know. I may also need a new clutch in mine so what I find normal may not be normal

 

Just an FYI, most aftermarket fan clutches are complete ****.