the heater in my 98 is not working too well... at low fan speed, its kinda warm, but on high there is barly any heat at all, even when the engine is completely warmed up. its full on coolant... i think the heater core must be pluged internally...is there anything else that could cause this? is there any easy way to change the core???

 

You could get a flushing kit and back flush the core

 

i might have to try that... my other thought is that when i bought the truck it had a v-10 in it with a small coolant leak and signs of bars leak in the radiator filler neck... i have heard that stuff will raise hell with heater cores, is there any product you might suggest to clean it out

 

I think if you go to a local parts store you can find a prestone flushing kit