We have a 2002 Dodge Ram 1500 pick up truck and have continually experienced problems with the heater core being gummed up to the point of not having any heat in the winter. We have replaced the heater core twice and have had the complete engine flushed numerous times only for this to happen over and over again. Nobody can tell us why this happens or what the actual gun is. We have made sure to use the proper antifreeze and distilled water in the cooling system and nothing stops this from occurring. We have owned this pick up truck since it was brand new and have taken extremely good care of it and quite honestly it still looks brand new. Trouble is, we have no heat. What’s up with this?
If your pickup has an automatic transmission, it could be that the transmission cooler section of the radiator is leaking transmission fluid into the radiator.
If that was the case I would think they would have ruined the transmission by now (running out of fluid) though I dont know why this keeps happening .
Rather than go through it all you might read through this and consider whether or not it’s a case of electrolysis gone wild or the possible lack of a restrictor plug in the core inlet tube.
In theory electrolysis should cause a pinhole but in the real world who knows.
This is all assuming there’s not a blend door issue or something of that nature at fault.
I am not sure how yours works but a quick search showed a heat control valve for your vehicle, maybe that is what is failing.