Should I drain both oil and antifreeze before starting to take apart engine for head gasket replacement???
Thanks in advance

 

Definitely drain the antifreeze from the radiator and the block. The head and intake contain a lot of antifreeze and this will spill everywhere when the parts are removed if not drained. Antifreeze in the head will spill into the cylinders and contaminate the oil.

Unless you plan to remove the oil pan in conjunction with changing the timing chain, I would wait to drain the oil until after the job is done because you will get junk into the oil pan during the block cleaning. Either way, change the oil again after you run the rebuilt engine for an hour or so to get all the machining debris and junk from the job out of the engine.

Bugs

 

I second the coolant dump first and then wait until the job is done to dump the oil. Lots of dirt and junk will get into the engine after you do the head gasket (dirt, metal shavings, gasket shavings, etc...)

 

Be careful when you are taking the head off because there is some coolant left in it. It managed to spill everywhere when i removed it .