how do you drain water jacket on 2008 sienna?

if you pull the thermostat housing and the lower radiator hose that should do it.you can also stuff a rag in the thermostat opening and blow air in beside the rag to be positive.

You don't have to drain it all out - fill with water several times and flush it out. When the effluent runs clear, re-install your hoses, etc. for refill. Pour in half of the cooling system volume with straight anti freeze. Add distilled water to finish the fill. That way any water left in the block will be part of he 50/50 mixture.

even if you use water you should still stuff a rag in beside it to put some pressure behind or you could be leaving residual coolant in the heater core.

Use of air pressure makes sense, but are you sure that there is a lower hose on this model vehicle. I am not in front of the vehicle right now, but recall that both of the hoses are at the top, on opposite sides of the motor.

and you should never mix anti freeze in the block there is no way to be possitive you have a 50-50 mix and there is a range. to little water and it freezes at warmer temps, to much water and it freezes at warmer temps. and by warmer i still mean below 32 deg. fer.

they may both come out close to top side of the motor, but at the radiator on will be on top and one on the bottom. hope this helps.

Shaggy - where do you think the shade tree mechanic is going to get the volume of air to blow out a block? Do you think all thermostats are right up front where you get to them if someone had a unlimited supply of air? The anti freeze is going to be completely mixed by the time the engine warms up for the first time. It follows the theorem of random dispersal of liquids. I learned about it in my heat transfer and fluid flow classes I took to become a nuclear reactor operator. What's your experience?

read the back of the damn. bottle, if it is not mixed right it is going to freeze. and you are a nuclear reactor operator. i am 31 and been working on everyday drivers, race cars and mud trucks since i was 13 and if you read his question you would know that he is aready going to have the thermistat removed, meaning he has the accsess. and yea you may be right, he may not have the air flow, thats why i agreed with you about water, but he needs to pressurize it because he wants to eliminate all the residual fluid,that was his initial question, including the heater core. look if you want to argue further i am fine with that, but got to my garage and message me. there is no need to do this in some inocient guys question page.

Being a generally non-confrontational bloke, it does make me a bit uncomfortable. I will drain what I can, dilute and re-drain a few times. And blow out the water jacket as best I can (I have a high volume blower used to winterize swimming pool if i can get appropriate access). Presumably, I can put the thermostat housing back on without installing the thermostat and blow the air through the hose. Do I need to be concerned about flushing the heater core, or will that naturally drain with the rest?

i appologize for that, no need for it. being that the heater core is the lowest point in the system, i personaly would not rely on it naturally draining. Drain it blow it, eighther water or air. leaving the thnermostat out, also no gasket (it is going to leak), refill with water. runn for 3-4 mins. drain, install thermostat, put back together and refill with coolant. that will remove any residual coolant with out question.