Posted by Vaughn on Tuesday, January 29, 2002 at 1:55PM :
In Reply to: 55PW Cab heater question. posted by Mike in Indiana on Tuesday, January 29, 2002 at 12:44PM :
Take out the head valve and make sure no rust buildup is plugging it. Then get some Prestone Radiator flush and drive it is the truck with the heater valve open. You probably have scale buildup on the core tubs restricting the coolant flow through the heater core.