Lazy coolant - anti-freeze

[HealeyV8]

I had a mechanic flush and change coolant on my 2002 E46 with M50 a couple of months back. He didn't do it quite right (probably didn't do the heater on full blast trick) as within a couple of days I had a low coolant light and I had to stick loads of water in it (didn't have antifreeze on me at the time).

I'm lazy and I wondered if I were to drain only 4 litres out if I could fill up with 4 litres of undiluted anti-freeze and get the car to mix it with the water already in it, would this harm it?

[Mignon]

Very roughly you want to drain out (Number of litres of water you put in x antifreeze concentration you desire)

[Oldandslow]

I've certainly topped up with pure antifreeze before. If you put it in the rad cap and get the engine up to temperature it'll be mixed through in no time.

[HRCM]

HealeyV8 said:

I had a mechanic flush and change coolant on my 2002 E46 with M50 a couple of months back. He didn't do it quite right (probably didn't do the heater on full blast trick) as within a couple of days I had a low coolant light and I had to stick loads of water in it (didn't have antifreeze on me at the time).

I'm lazy and I wondered if I were to drain only 4 litres out if I could fill up with 4 litres of undiluted anti-freeze and get the car to mix it with the water already in it, would this harm it?

Hi, are you sure the system was bled properly via the bleed screw?

I had no problems after changing my coolant on my E90 diesel (M47). I just started at the lowest and sequentially closed the three bleed screws when the bubbles stopped.

Bleeding with the heater turned to 'Hot' helps but it's not essential for every car; only if there is a valve on the inlet to the heater matrix. It doesn't do any harm to turn it on though and does speed things up plus I like the feedback that the vented air getting warm provides :-)

I found this for you. A very helpful website generally. I've used it a few times now.

https://www.pelicanparts.com/BMW/techarticles/BMW-...

Matt

[HealeyV8]

HRCM said:

Hi, are you sure the system was bled properly via the bleed screw?

I had no problems after changing my coolant on my E90 diesel (M47). I just started at the lowest and sequentially closed the three bleed screws when the bubbles stopped.

Bleeding with the heater turned to 'Hot' helps but it's not essential for every car; only if there is a valve on the inlet to the heater matrix. It doesn't do any harm to turn it on though and does speed things up plus I like the feedback that the vented air getting warm provides :-)

I found this for you. A very helpful website generally. I've used it a few times now.

https://www.pelicanparts.com/BMW/techarticles/BMW-...

Matt

I assume he didn't run the heating system without the car running. If I hadn't Googled it I would have just run the car with cap off until I couldn't fill it any more and it had stopped "burping" as this is what i've always done on other cars. All I know is that within a day or so I got the low coolant light and had to poor several litres of water in.
It was plain water so I want to drain out around 4 litres and top up with consentrate.