To make it that much harder to accomplish the task at hand: with the heater core participating in engine cooling it takes just that much longer to get the thermostat open, and it closes again just that much faster. Especially when it's good and cold out.

 

^probably just standard instructions.

i had an 88 dodge minivan and IIRC it had a heater flow valve, which keeps the hot coolant out of the air box.

 

Have you driven the truck much? Mine will always kinda work any air pockets it might have out itself after a while. Just have to drive it around and then top it off. Never really attempted burping the system, have never had to after radiator, heater core, or water pump replacement. Weird.

 

i've never had a problem either. i just run it with the cap off till the t-stat opens. top it off, close it up, and drive it. it sloshes for 1-2 days and then stops. a final top off of the overflow tank and its done.

 

Mine does it every once in a while but the engine never overheats so I just ignor it. I am however corious about this heater core flush for more heat.... More info please?

 

Basically, its take the hose off the tube going into the water pump, separate the other side hose at the splice, and flow water/air/whathaveyou thru the heater core in both directions. Some have used compressed air, others have used the garden hose, yet others went to the pressure washer, and used that....... You could even dump some chemicals into it, let them soak in for a bit, and then flush it.

 

You know entirely too much about these trucks

 

I'd be leary of the pressure washer if its an old heater core...might clean it out good, or might make it leak. Or both maybe, which would be a waste of quarters at the car wash.

 

Here is what I did to back flush my heater core.

1) Dissconect the heater core hoses from the engine block
2) Use compressed air to back flush the coolent out of the core
3) Pour water into the core and back flush it several times
4) Put some kind of cleaner in the core (I used CLR)
5) Let the cleaner sit for an hour
6) Back flush the cleaner out
7) Pour water in and back flush the core another several times
8) Connect the heater core hoses to the engine bock.
9) Re fill and burp the cooling syestem
10) Feel that wonderfull heat

Before I did this I had zero heat, now it cooks me out of the truck.