Try to just flush the core out with a hose. Disconnectboth lines going in to it and hook the garden hose up and just let it push the crud out. Only takes a minute.

 

Well, those who guessed water pump were right.

Yesterday morning it was 8 degrees and my radiator went. The quality of the coolant didn't help. But, I think it was the water pump's fault. Once he got the radiator in - still no heat and the temp gauge kept crawling upward.

I should be back on the road tonight on my way to St Louis. Wish me luck.

Thanks for all the help. This is a great forum!