MrViet

Like title says, do i have to drain coolant in order to put my thermostat in?

follie gatts

no. let your car warm up with the radiator cap off when you're done to let the air in the system bubble out.

rayzah_blade

sooo, how is he to get to the thermostat, without taking off the radiator hose, since it will still be filled with coolant???.....

follie gatts

some of it is bound to escape, but there is no point in removing the radiator drain plug or even the block drain bolt. neither of which, by the way, would remove all the coolant from the hose you are talking about anyway.

Dogginator

You have to drain the coolant below the housing. Since your thermostat is bad (stuck open) the coolant will drain just fine. It would drain just fine with the weep hole anyway.

rayzah_blade

this statement leads me to believe that you have never removed the thermo, possibly even changed your coolant.. the thermostat is located in spot where there is coolant heavily populating the areas surrounding it, and removing the hose leading to the thermo will most definitely allow coolant to pour all over the place, essentially draining the coolant anyways.. I suppose if there was only a quart in the system, there may not be a need to drain, but if your running your car with only a quart of coolant there are bigger issues at stake.

Mattb16teg

Technically, yes you should, on the fly I have done it many times without doing so and letting coolant drain into a pan once I unbolt the housing.

MrViet

thank you all very much. so conclusion is that i don't have to flush coolant. thank you.

Mattb16teg

No, is that you should, if you do not coolant will go everywhere!

hybrid90

You technically don't have to. I just used a pan to collect the coolant that's spilled out a lil (if not done right.. it might get a lil messy).. but I mean.. while you're at it.. you might as well just change everything fresh and new.

Dogginator

Not draining coolant = a big mess
Draining coolant = a little mess

Choose wisely.

steveo135

would probably be healthy for the car.. when was the last time coolant was flushed.. if it was recently I would say just let whatever comes out, come out and refill as needed.. as dogg said will be messy though

vladd

i went with "big mess" when i did mine. it's a pretty quick job if you don't take the time to drain it.

dothacker

when i changed my thermostat, i drained all my coolant and changed my fan switch too while i'm working on the same area.

follie gatts

ORLY do you want picture proof? do you want me to scan my thermostat and radiator barn receipts? maybe i'll go outside and put a level between the thermostat housing and the radiator, and then we can debate how much coolant is below that level depending on the pitch of my driveway and barometer pressure.

Dogginator

The coolant will drain with the thermostat installed. I have done this many times before. You just have to wait a bit. The exception would be if the thermostat was physically clogged.

rayzah_blade

yes, you will need to do exactly that.

STRDAGEY88

I changed my thermostat last week without draining the coolant... but when you pull the hose off coolant is going to come out of the hose. Also when you pull the thermostat coolant is going to start draining from behind it. So basically if you can get the old thermostat out and put the new one in quickly you should be fine. I learned this the hard way. have an oil pan or something to collect under the car