# How to flush coolant system properly?



## TheVarix (Apr 3, 2013)

I want to do a proper flush to the system but I have never done it before. I don't have access to a hose and I wouldn't like to use tap water when flushing if possible as I think as some of that tap water will remain, that could potentially cause some crap deposits to form. :?: 
I'd rather use distilled water when clearing the system even if it's more expensive. Does this make any sense? :?: 
After draining radiator, I believe that there will be some coolant still left in the block. Here's where I am not sure what to do to get rid of that...Filling with water and flushing twice until it's clear? 
I have also read about filling with water and run the engine with heater on high to clear heater core of coolant. 
Could any kind person here help me, please? Or perhaps link to a good tutorial / write up? [smiley=book2.gif] 
I am also going to replace the expansion tank as it's quite brown and you can't really see the coolant level. What do you recommend for the ratio of distilled water to coolant? 50/50? 
Also, are the flushing products out there any good?
Many thanks!!


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## Hoggy (May 8, 2002)

Hi, Without a hose, you will require many buckets of distilled water to flush correctly. 
Tap water shouldn't cause any probs, scale is only left behind if coolant is boiled off & as it's a sealed system & should be a leak less system, then coolant won't boil off so no scale should be left in system.
When finally refilled with distilled water, to remove any air locks put heating on hot & remove coolant reservoir cap, as coolant moves around & heats up any air will be removed, top up as required. 
Hoggy.


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## TheVarix (Apr 3, 2013)

Thanks for your reply Hoggy! 

Many thanks for clarifying that about scale deposits using tap water. So the way I understand it, the procedure would then be something like this:

1)Drain radiator, refill with water. Run engine until reaching operating temperature. Let cool and drain. 
2)Fill up with water again and run engine until it reaches operating temperature. Let cool and drain. Check colour of drained liquid and if it's not clear enough, repeat again? 
3)Fill up, this time with a 50/50 ratio mix of distilled water and G12 coolant. Run the engine without expansion tank cap and heater blowing on max. temp. to get rid of any trapped air. Top up if necessary.

I am aware that if you pour cold liquid into a hot engine you could potentially crack the block so do you think 1 and a half hours of cooling down is safe enough before you fill up with liquid or does it need longer? :?:


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## Hoggy (May 8, 2002)

Hi, I wouldn't think it necessary to run engine up to temp as there is a drain before thermostat on bottom hose. 
Run engine to move water around, drain, refill & repeat until you are happy to refill with distilled water. 
Yes 50/50 mix, max. 
Hoggy.


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## TheVarix (Apr 3, 2013)

Many thanks again for your reply Hoggy!! 

Will try tomorrow (weather permitting) + an oil and filter change to keep my car happy!


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## Shootist (Mar 10, 2013)

Too much antifreeze reduces the cooling efficiency of the system. I cannot think of anywhere in the UK that would need more than a 40/60 mixture and I doubt you would have any issues with using a 33/67 mixture.


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## TheVarix (Apr 3, 2013)

Thanks for that. Will do a 40/60 ratio instead as I've seen a Thermostat replacement guide here that mentions this ratio as well.


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