Technical Siphon coolant?

[itssph]

Looking to change coolant on daughter's 1.2 8v Dynamic Eco, 2010. Haynes book says remove bottom hose but don't like the look of that, looks too easy to damage something. Can I siphon pump it and if so do I just get the tube as far down into the expansion tank as I can? Will make sure I can open the bleed screws before I even start the job. If this method works will it get most of the coolant out?

 

[jrkitching]

Yes, this is actually the method I'd recommend on versions (like yours) with the expansion tank at the side of the radiator. You can get a hose right down to the lowest point of the system and you'll get just as much coolant out as you would by removing the bottom hose. Done this myself several times now.

Whatever method you choose, there'll be quite a bit of coolant left in the heater circuit - there's not much you can do about this. It can help to measure what comes out, so that you know how much you need to put back.

You might not get it all in on the first attempt; this isn't unusual. Opening the bleed screws likely won't help much, also they're quite fragile and easily broken. Fortunately the system will self bleed in service. Just top up to the max, run it up to operating temperature, and top it up again once it's cooled. It may take a few cycles, but eventually it will stabilise.

 

[itssph]

Ok guess I could fill with plain water first run it up to temperature to dilute what's left and clear some rubbish out. Thanks for the warning on the bleed screws I'll leave well alone

 

[jrkitching]

I could fill with plain water first run it up to temperature

I wouldn't recommend it. Plain tap water at 90C is corrosive, and running up to temperature without sufficient anticorrosion additives in the coolant could permanently damage the aluminium cored radiator.

Unless it's been run without the correct antifreeze in the past, it's unlikely there'll be any significant contamination in the old coolant. If there is, it'll likely collect at the bottom of the expansion tank and thus will get syphoned out. Just get out what you can, refill with fresh coolant and it'll be just fine.

 

[DaveMcT]

You could flush the system with dehumidifier water (which is distilled water). Ideally filtered through a kitchen towel. Then drop the flushing water and add 50%** of the system volume as antifreeze. Top up with distilled water. That way you know the coolant is at least 50%.

** Depending on the concentrate to water %age you want to use.

The easiest and safest way is as described. but when that bottom hose has to come off, cut the crimped clamp and use a worn drive clip. The QD connector exists to assist the factory installation. It's likely to be less than easy to disconnect when you need it to.

 

[itssph]

You could flush the system with dehumidifier water (which is distilled water). Ideally filtered through a kitchen towel. Then drop the flushing water and add 50%** of the system volume as antifreeze. Top up with distilled water. That way you know the coolant is at least 50%.

** Depending on the concentrate to water %age you want to use.

The easiest and safest way is as described. but when that bottom hose has to come off, cut the crimped clamp and use a worn drive clip. The QD connector exists to assist the factory installation. It's likely to be less than easy to disconnect when you need it to.

Thanks might do that, I can use tap water where I am, very soft Lake District water. Thanks for the comments from both contributors, will siphon and replace what I can and call it job done, can't see her keeping the car more than a couple of years.

 

[DaveMcT]

Tap water in soft water areas can be acidic. It's worth joining a pH dip test. Distilled is a better option.

 

[itssph]

I believe it's slightly alkaline, pH is meant to be between 7 and 8 (as stated by UU). Having said that I'm going to try and avoid flushing as long as I can siphon most of it out. Will fill with ready mixed stuff if that's the case. Thanks.

 

[DaveMcT]

pH between 7 and 8 is quite a wide range so soft tap water might be ok.