Where is the drain located for the coolant. I am draining it and putting fully distilled water. Then after a week I will drain it out putting a full 50/50 mixture of coolant and antifreeze.

 

There is a drain on the radiator, which can be accessed from below. It should be a 19mm fitting on the lower RH side tank.

 

Hi omgimali,

Sorry in advance for this lengthy post, especially if you already know all of this:

The entire X308 cooling system holds about 10 liters of coolant, but draining from the radiator drain plug leaves a significant amount of coolant in the system. The engine alone holds 3.7 liters. So if you drain and refill with distilled water, the system will still contain nearly 2 liters of coolant. Draining and refilling with distilled water will further decrease the amount of old coolant in the system.

When I remember to, I measure how much old coolant drains out, because this helps me know how to achieve close to a 50/50 mix in the final refill.

The issue to think about is that when you do the final drain before your final fill, around half the system will remain full of distilled water with a low concentration of old coolant. If you top up the system with a 50/50 mix of fresh coolant and distilled water, the resulting concentration may only be 25% coolant and 75% water. Maybe even 20%/80%.

So, unless you go to the trouble of draining the entire system via the A- and B-bank block drain plugs and/or cooler lines, I would suggest that on your final drain and refill, you first add pure concentrated coolant to mix with the distilled water that remains in the system.

If I have remembered to measure how much coolant mix drained out from the radiator drain, I can calculate how much pure coolant concentrate to add back to result in a 50/50 mix with the distilled water remaining in the system. I can then top up the rest of the system with a 50/50 mix.

If I have forgotten to measure how much coolant drained out, I add one gallon of pure coolant concentrate to start. I then add enough 50/50 mix until coolant is visible in the bottom of the reservoir, but I don't fill the reservoir.

Now I run the engine with the climate system set to heat so coolant will circulate through the heater core. I watch the coolant level in the reservoir and add more 50/50 mix to keep coolant visible at the bottom of the reservoir. Once the temperature gauge in the instrument cluster indicates the engine has reached full operating temperature, I shut it off and let it cool.

When it's cool enough to open the reservoir, I use an inexpensive coolant hydrometer to draw some coolant/water mix out of the reservoir to test its protective properties. This tells me if I need to top up the coolant reservoir with pure coolant concentrate, or a 50/50 mix, or pure distilled water in order to achieve the appropriate protection, typically a freezing point of at least -34F/-37C and a boiling point of at least 265F/129C.

Cheers,

Don

 

Why don't you remove the lower radiator hose at the engine block in addition to the radiator drain **** , this will completely drain the coolant in the block and the radiator.

 

Remove the 17mm hex plug on the left side of the block to drain most of the coolant from the block.

I do this everytime I remove the cylinder heads to prevent the remaining coolant from spilling when the heads are removed.

bob

 

Unfortunately that doesn't work. The lower radiator hose connects to the thermostat housing at the top of the engine, so disconnecting it will not drain the block. To more fully drain the block, in particular the B bank, you have to remove the drain plug Bob described. And to more fully drain the A bank you have to disconnect the coolant pipe on the other side. Here are the instructions from page 907 of the X308 Workshop Manual:




For normal flushing and refilling, I don't bother with either the block drain or the coolant pipe. I just follow the procedure I outlined previously.

Cheers,

Don

 

That's a great write-up.

I just wonder how you manage to measure how much you drain?
I always seem to end up with a big mess on the floor, and little in the big canister I put under the car.
Seems the fluid splashes straight at a girder, splashing it everywhere, if I open the drain.

 

I open the drain plug just enough to get a small stream. If you open the drain plug all the way, coolant sprays everywhere. I use a large-mouth drain pan to catch nearly all of the coolant. I move the pan around when the stream shifts directions as the coolant level in the radiator declines:

Then I pour the coolant from the catch pan into a measuring bucket. The "Mix 'n Measure" ones I buy at a local home store hold 5 gallons and are graduated in quarts and liters for easy measurement:



Cheers,

Don

 

Ok so if i flush the entire system twice with distilled water. I then do the final flush and only 1.5 gallons of water comes out (with the full capacity being 2.6 gallons*) I then top up with concentrate (1.1 Gallons)? Guessing that 1.5 gallons of water comes out.