My dad's 03 PSD is getting pretty iffy with the heat (120k miles). It works fine if your driving, but as soon as you let it idle or let of the throttle it starts to lose the warmth and gets cold. As far as i know the engine temp is stayin normal, so what could be causing this? Is that normal for 20* weather, or is there a problem with the heater core or somethin along those lines?

 

sounds like the heater core is getting stoped up. A flush should solve the problem. plus getting a coolant bypass filter would help prevent it from doing it again. dieselsite makes one that is very popular on here. I plan to get one.

 

I agree on the heater core.
When I was talking with Doug at GoGoDiesel/Direct Inj. Perf. he mentioned that it's common for the heater core to get clogged with all the stuff that the coolant filter will take out. I ordered my coolant filter kit for my 07 from him.

 

Alright so besides ordering a coolant bypass filter, whats the next move? Do we need to remove the heater core and clean it out?

 

have it flushed out real good that should solve the problem. A bypass filter would be the next step.

 

Where is the heater core at? Im new to the 6.0 and don't have too much knowledge on it.

 

the supply hose goes in through the firewall on the passenger side then the return line comes out and runs along the firewall to the bottom of the degas bottle. disconnect the supply line after this valve


then take it off the bottom of the degas bottle. get yourself a garden hose and flush it backwards from the degas side to the valve side. run water through it until you don't see anymore crud coming out and it should be good.