Hi I have a 2004 Chevy Venture 3.4 with 167,000 miles on it. I had a leaking intake gasket and after fixing and completing it I broke the 8mm rocker bolt on one of the valves. I then did a Heli-Coil thread repair on that valve and put everything back together. After I started the van up it made a valve noise so I decide to change the heads (used heads) on both sides with the better 10mm bolt head (which don't break) and a brand new head gasket. After 4 days it started mixing oil and radiator fluid on the top of the engine and not the lower half and it’s also losing anti-freeze and its burning 2 quarts of oil every 4 days. It's also overheating due to coolant and oil loss at the same time. It’s not smoking from the tail pipe, it’s not leaking anywhere and the head gasket is brand new. What could be the issue?