Finally got around to replacing my old block heater today. This is not an easy job if you have to replace the block heater rather than just install one. Its really difficult to get the old one out of the bore that is machined into the block. I bought some Silver and Demmings HSS hardened drill bits as I knew the old block heater had to be drilled out. After I broke off the heater's element, this is what I was left with and started to drill it with regular HSS drill bits. This metal (not sure what it is) is extremely hard.
This was the progress using a 9/16" Silver and Demmings with 1/2" reduced shank.
Next went up to a 3/4", then to a 7/8" Silver and Demmings bits. Finally drilled with a 15/16" Silver and Demmings and got it free.
Here is the bit sequence I followed to get the old block heater out of the block bore.
And a picture of the bore ready for the new block heater.
Here are a couple of others showing how the old block heater came out.
Very happy that job is done and the RAM is ready for the -40 C temps we get here during the winter months. Feels good!!!!!