Ressurrecting this with a new question. I finally got about to finishing this, which involved removing the fan pulley and A/C compressor, of course, buttoned it all back up and tested it w/ a pressure tester I rented. Coolant and air bubbled out the housing/block union. So, took it apart and took another look and found some pitting on the mating surface of the housing. I was thinking about using JB weld to fill the slight pit and sanding it flush, then trying again. I did use Permatex water pump gasket maker the first try (in addition to paper gasket), though I could also try just using more Permatex to fill the pitting. Thoughts? I'm not too keen on having to do this job a third time, so trying to get it right this time!

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)