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How did you flush out the heater core? Also, are both hoses to the heater core hot with the heat on?


As for later heads on the '98, pretty sure that the '99-04 #0331 heads require a different exhaust manifold. Plus they are known for problems with cracks.





Took the heater core lines off at the nipple fittings (on the engine). Flushed them with semi-high pressure water, back and forth till the water ran clean and open. I think the both heater hoses are hot.