got a strange little conundrum here, my truck since the day i bought it hasnt had heat. figure its the heater core and procrastinate doing it, i put a tstat in it with the hopes of a change and well at first it did. after bleeding the air out of the system the interior was toasty. i put the radiator cap on and went home from work. next day no heat. weeks later there i am, sitting at home thinking about just doing the core on sunday. last night i went to the bar to throw some darts, i get there, truck still running i pulled the radiator cap, minimal release of pressure but thats been my experience with all my second gens. they dont really explode in a skin melting display of coolant, anyways, i get back in the truck and instantly there was heat. it just came on when i took the cap off, put the cap back on and went inside. hours later i remote start it and let it sit for a bit and when i leave there was no heat. makes no sense, anyone have some ideas????

 

Sounds like it keeps getting a huge air bubble in the system which releases when you open the cap. Have you done a flush of the heater core? Do the park-up-hill-cap-off trick? New cap? New pump? Ultimately, core is king. I fought weak heat for years (blamed it on the 180 stat) and finally did it last spring. Holy cow there's heat before the needle moves!

 

 

I had a mechanic shop tell me that one of the culprits of Dodge heater cores clogging up or springing leaks was insufficient grounding. He said if you would attach a wire between the heater core and the body metal, it would make the problem go away.....wish I had known that when I had to change out mine on my '95.

 

Why would the heater core need to be grounded? Not like it passes any current? I could see it as maybe a curb for electrolysis.... but even that is a serious stretch.

 

I wondered the same thing when i was changing mine and seen the ground strap going to it. For whatever reason i put it on the new one.

 

Well, there is a puzzle that is going to keep me up tonight.

 

And just for fun, here's a link that tells you NOT to ground the heater core, and explains why.

 

Yeah, the core is already grounded. Whatever.

 

I have exactly the same problem. I reviewed about twenty pages of posts yesterday and it seems like an air bubble in the system is the most likely candidate followed by a problem with the door in the distribution box. I'm searching for a big hill. We got our first snow yesterday and I seriously needed heat from my defroster.