Got a 2000 durango 5.9 R/T that I'm at my wits end with! JUST hit 100,000k miles!! Ok, starting in Jan 2010, the radiator blew. Replaced that. Not even 2 weeks later, water pump leaking. Replaced water pump, thermostat, hoses. STILL LEAKING. Suspected freeze plugs. Added stop leak pellets to get me through the week...it worked, no leaks. In the meantime, it through a code - transmission. Suprise, it's a dodge!( Went ahead and had the trans reman'd because I'd been down that road with dodges numerous times before. ) During that process, had all the freeze plugs replaced with copper ones, and the trans lines flushed. STILL LEAKING!!! (grrr!) based off from advise, and process of elimination, (also inspected timing chain cover for errosion) suspected water pump gasket may have not been installed correctly. Replaced that with an aftermarket gasket...YAY! No more leaks! Now, yesterday, 3 months to the day after all this began, radiator blows! It was 3 hours after my husband got home from work, we stepped outside to smoke a cig when for no reason, PSSST! radiator just blow, gushing antifreeze, yet again! The one thing that was not replaced was the radiator cap, because that was replaced in the last year. OK, let back up a min...sometime last year it quit producing heat as well. Now, looking at the cap, it says 18PSI, which at that point a light went off in my head...GEEZ thats a high psi, that would explain all the problems, no heat, exploding radiators, excess pressure in the system...sweet, easy fit! NOPE! called the dodge dealer today, and its supposed to have a 21PSI cap!!!!!!

I doubt it's a warpped head, although plan to check that anyway this weekend, because there is no excess bubbling when the cap is off and vehicle is running, and its not forcing anything intothe overflow. It drives fine mechanically otherwise. ANY suggestions would be GREATLY appreciated!!!

 

if you dont have heat, you probably have a clogged heater core, you could back flush it if you want to try that, or replace it, either way the entire cooling system needs to be flushed, you need to use a 50/50 mix with DISTILLED WATER in the cooling system, if you had to replace your transmission that is a separate issue, and i hope that you had it rebuilt with a shift kit, but that is for another thread please and if it blew after just sitting for a while it sounds to me like you got a faulty part installed, if it was done by a shop it should still be under some sort of 'warranty' take it back and complain

 

Yeah, all the parts have "lifetime" warrenties. So first things first, getting back in there to replace the radiator! I've been using the premix or 50/50 -antifreeze/distilled water. (I should've taken stock in antifreeze!) The reason I brought up the trans was because in the process of that, the entire system was flushed (not just the lines) because last august, I went through this with my 96 ram...trans burned up due to clog in the system. When the vehicle is running, the temp gauge indicates just below the half mark....?

 

that is a normal temp reading on these trucks, and you should NEVER FLUSH a chrysler motors transmission, it causes way more problems than it solves, when they replaced the transmisison did you make sure that they used atf +4 fluid? and in all of this did they replace the trans cooler (if you have one that is)

 

Oh I know...NEVER flush a dodge transmission! (I had a complete reman job done on it, and yes I know to use ATF+4...my husband is a (honda)tech and I work in a parts store...we're not complete idiots, lol. And the trans cooler is internal in the radiator, which again, was replaced. (On the ram, same thing, but we actually put an external cooler on it too) The reason I brought up the temp gauge readings is that because it is indicating normal temp readings, I'm at a loss as to where to go from here. No warnings, it just blows when it wants to! (Its sort of hard to express my meanings in type I suppose)

Pretty much what I am looking for is, if anyone has experienced something like this before, am I maybe overlooking something? Since we've replaced the hoses, thermostate, water pump, and radiator, plus had the cooling system flushed, where do I go from here?
Now, I know NOTHING of the A/C system, but a radiator shop did mention that if there was an issue with the A/C system, this could cause my issues - ever heard anything about that, or know anything about that?

 

CAP!! it is the pressure controll of the system. if it's rated too high as you have allready surmised popping heater cores & radiators are the result. Even a cap of proper rating can stick & cause an overpressure fail. Replace the cap with a name brand one of the proper rating.

the engine is it's hottest right after shutdown. no more coolant flow & no cool air comming in. after you shut it off it got hotter gaining more pressure till the radiator decided it was out. in a way the delay prooves no head gasket problem to that point. if the system held a high pressure that long after shutdown the gaskets must be tight.

 

Good Point Dislander, about being able to hold the pressure for so long. Yeah, I'm gonna replace the cap too.

I know some vehicles have a cooling sytem bleeder valve on the actual engine, or sometimes below the thermostat; looks just like a brake bleeder valve/screw. Checked around the thermostate, but didn't see anything. Has anyone ever come across this on the 5.9 and if so, where is it at?