Changing coolant in radiator

**Blue2KTA** · 06-07-2009, 07:16 AM

I want to drain the coolant in the radiator and pour some new dexcool in. I'm not looking to do a full flush, just replace whats in the radiator. Do i just open the drain cock, drain it all out and replace with 50/50 ? Will air get into the block if only drain the radiator ?

Thanks

**ls1camino** · 06-07-2009, 09:36 AM

There's almost no point in just changing what's in the radiator, it's only 1/2 of what is in your system. If you're dead set on just doing the radiator, then yes, just open the drain and let it empty out, then fill it with what you have in there...DO NOT MIX THE ORANGE STUFF WITH THE GREEN STUFF!!! 50/50 is best. No, air will work it's way out, the system is designed to do so.

**pajeff02** · 06-07-2009, 01:48 PM

There is quite a bit of coolant that remains in the block if you simply drain the radiator. The block drains are not all that bad to get to. On the passenger side, the drain is located above the starter. Use a 5/16" allen head on a 9" extension (it may actually be metric, but this had the best fit).

On the driver side, the drain is a 17mm allen head located above and behind the alternator. The only thing I had to remove was the alternator splash guard. You can purchase a set of large allen head sockets from Autozone for about $12.00.

There is an air bleed built into the thermostat to allow air to escape as the system is filled. I just did a slow fill over time, adding a bit of coolant every 5-10 minutes, rocking the car and bouncing it on the suspension helps work the air out.

On start up, just keep an eye on your gauges. You can also feel your hoses (careful of the belts) to ensure that coolant is flowing. If you are going to the trouble of dropping the coolant, it is best to get all the old stuff out. Flushing it is even better (no chemical flush!) and is easiest with the thermostat removed from the housing.

**Blue2KTA** · 06-07-2009, 03:32 PM

Thanks for the info guys

**egod** · 06-07-2009, 03:55 PM

when i did mine i just drained it at the radiator, then filled with water and ran it open until it was all water. Then seal it up, top it off with coolant, run it while adding more fluids.

**pajeff02** · 06-07-2009, 04:06 PM

Originally Posted by egod

when i did mine i just drained it at the radiator, then filled with water and ran it open until it was all water. Then seal it up, top it off with coolant, run it while adding more fluids.

I started to do this, but after several fill and drain cycles it was still running pretty "colored". That's when I said the heck with it and went shopping for a socket to do the driver side drain plug. After I dropped the drain plugs, and realized just how much coolant was still in the block, I was glad I did.

**egod** · 06-07-2009, 04:31 PM

while it was running i kept the hose in the radiator the whole time, only took a few minutes

**pajeff02** · 06-07-2009, 04:37 PM

Originally Posted by egod

while it was running i kept the hose in the radiator the whole time, only took a few minutes

Did you have the thermostat out, or were you using hot water? Seems like the cold water would close the stat and not allow the coolant to circulate through the block.

**egod** · 06-07-2009, 06:39 PM

i belive i had my thermostat out but had the housing in still and everything connected

**pajeff02** · 06-08-2009, 04:34 AM

Originally Posted by egod

i belive i had my thermostat out but had the housing in still and everything connected

That's how I did it. I gutted my old housing, then just started the engine to circulate the coolant. Also kept the heater set on "hot" to flush the core. Once it cooled down, I drained everything again and repeated this cycle a few times until the water ran clear.