Accidentally overfilled the tank by a lot. I did a coolant flush and was tired and added too much coolant to the overflow tank. Is there a way I can maybe drain it without taking a lot of things apart?

 

Just create a gravity siphon with any hose/tubing.
Or... if you hate nature, just drive the car and as it expands it'll just bleed off excess on the road.

 

Won't driving the car without doing that cause problems? Besides just spilling toxic liquid onto the street

 

Nope, the overflow tank is just that - a place to capture "excess" coolant. Here's how the system works:

Starting with the engine, radiator, heater core and all coolant hoses/plumbing fully topped off with coolant and burped of all air, and a proper working pressure cap, as coolant gets hot driving it will expand and increase pressure up to the cap's rating. Typically if the system is healthy it wont exceed that cap pressure in operation, but if it does, the cap opens and coolant can now flow to the overflow tank. More commonly, when you shut the car off hot, since the coolant is no longer flowing, the engine heat soaks, coolant temp/pressure increases and some coolant will flow to the overflow tank. As the engine cools down, it creates a vacuum in the engine's coolant system, and the coolant is pulled from the overflow tank back into the engine, replacing what was sent to the overflow tank.

 

I see! Thanks! I hope everything will be fine

 

Use a turkey baster with a bit of hose on the business end to suck some of the coolant out of the overflow tank.

 

That worked! Thanks

 

I'll just add, mitivac with the brake bleeding attachment if you don't have a turkey baster lying around (I guess more people have turkey basters than mitivacs but not me...)

 

One of each, just in case!