Did a full coolant flush and change of coolant type over the weekend. While the instructions posted by Aston1936 are really useful, my car with the later AM29 engine has a different radiator hose layout, and more importantly, no petcock to drain from!

I first flushed the entire coolant, and got 13.8L (out of 15!) out by evacuating remaining coolant from the radiator (more on that later). Did a fill with distill water and ran the car hot to get the heater core to flush out. Then did a final flush and fill.

As I mentioned, my radiator doesn't have a drain valve, and also, there are no hose connectors at the lower end. However, the hose connects to the engine / water pump at a low point, so draining the engine by gravity is quite easy.

The hoses on my 2017 use push-install plastic surfaces with a metal locking wire, similar to BMW fittings.

As for refill, I opted NOT to go with the OAT type coolant that the car comes with. While generally good, OAT coolant (and Dexcool) contain 2-EHA rust inhibitors that are incompatible with Silicone and other rubber based products.

Instead, I used Peak 10x Coolant. It has a much longer service life, is actually mix compatible with OAT (and all other coolants). Got it on sale for $8 / gallon, and combined with a $7 mail in rebate, ended getting it pretty much for free.

For fill procedure, I used a vacuum based fill tool. This helped me confirm the cooling system can hold a vacuum properly (thus no leaks), and refilled with no air gaps.

As you can see, on my 2017 the left side of the radiator where the return hose is located is 1/2 way up the side:

However, the left side hose connects quite low and so the block and 1/2 the rad drains out easily:






I evacuated the radiator through the top hose connector. Hose is easy to disconnect with the push-install and metal wire lock





The flushed coolant had quite a bit of aluminum (machining and radiator filings) and noticeable black rubber bits:


After flushing out the core with a pure distilled water warmup, I went ahead and refilled Peak 10x from a 10L jug with the vacuum fill tool. Made sure the system held vacuum and then refilled.


Finally, confirmed no air gaps, ran the car hot and heater at full blast so the previous water used got mixed in with the new coolant good for the next 10+ years

 

Good pics. I did my '17 V12V last year and it does have the drain valve on the passenger side rad. Will post a pic when I find it.

 

Mine must be hidden there then. The service manual shows it exists for the older model, but when it comes to my year, that step is skipped, so I assumed it was removed.

 

Takes a while to locate but mine has a yellow pen mark on it. Still a messy drain.

TBH, I was worried that the valve wouldn't seal properly. The lock was just a click. So far so good.

edit: just realized yours is a '17 Rapide S. Tagged the pic I posted for future reference.

'17 V12 Vantage S

 

Just curious for next time.
I just finished my coolant change and i didn't find that drain port.
Besides the belly pan did you have to remove other items for access?

 

Just the belly pan. I had to reach in a bit half an arm's length to turn the valve I reckon. The pic was probably taken with a bit of zoom.