I’m going to get started on replacing my head gasket this week, but I don’t think I’ll be able to do it all in one sitting. Is that going to be necessary, though? I can wait until the weekend if that’s the case. I keep the car outside, and I don’t want any water, dirt, or bugs getting inside of the engine. Would it be safe to just lightly clamp/rubber-band plastic bags over any openings that I have to leave? And if so, will that be sufficient in the event of rain? I’ve seen that it should be a 5-hour job for an experienced mechanic, so I’m guessing it will take me around 10, give or take a few, plus however long it takes me to have the cylinder head pressure tested at a shop. (Also, out of curiosity... Am I supposed to test the head itself, the cover, or both?) I also need to flush my coolant while I’m at it. (oil is leaking outward through the gasket into the coolant, so I’m replacing it before the leak starts going the other way) That’s why I want to space it out over two or three days.