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Coolant Questions: Do you mix with water? What is radiator capacity?

odanny

New member
Location
Illinois
All of a sudden I'm getting the thermometer flashing light on start up, not every time but just every now and then, winter is coming, and I'm thinking of just flushing the system. For those who have done this, do you run anything in your system before draining the coolant?

I have the factory coolant already, is it a 50/50 mix? I don't want to burn up my water pump with straight coolant. What is the radiator capacity, will one gallon of coolant be enough? Thanks all.
 

Cjpolokid

Ready to race!
Location
New York
All of a sudden I'm getting the thermometer flashing light on start up, not every time but just every now and then, winter is coming, and I'm thinking of just flushing the system. For those who have done this, do you run anything in your system before draining the coolant?



I have the factory coolant already, is it a 50/50 mix? I don't want to burn up my water pump with straight coolant. What is the radiator capacity, will one gallon of coolant be enough? Thanks all.


Just change the thermostat. Adding water will just dilute the coolant.


Sent from my iPhone using Tapatalk
 

vwengineer

Ready to race!
Location
Switzerland
I think the factory coolant is straight coolant but you should confirm with others. If it appears to be much less fluid than water then it's probably not a premix
 

GTI's

Go Kart Champion
Location
MD
All of a sudden I'm getting the thermometer flashing light on start up, not every time but just every now and then, winter is coming, and I'm thinking of just flushing the system. For those who have done this, do you run anything in your system before draining the coolant?

I have the factory coolant already, is it a 50/50 mix? I don't want to burn up my water pump with straight coolant. What is the radiator capacity, will one gallon of coolant be enough? Thanks all.
Total coolant capacity for the system is 10 qtrs. (9.5l), just buy enough distilled water and proper coolant and mix it to the ratio you want, which it look like you are shooting for 50/50.

I personally have never used any chemicals to flush the system but I have never had a cooling system that was so poorly maintained that it needed it. Have seen a few issues with people that have and it blocked part of the radiator after chemical flushes.
 

Fred930

Scirocco MK II Track Car
Location
Wisconsin
In the "old" days, I'd just buy a gallon or two of Prestone at Walmart, and mix to the proper ratio with Distilled water. But as the metallurgy in cars has gotten more complicated, and as I've acquired more cars, I decided a few years ago to either buy factory fluids from the Dealer, or the exact equivalent from my buddy who runs a race shop (with access to professional after-market substitutes).

Putting the incorrect fluid in your radiator, brake system, transmission, power steering, or engine oil can be disastrous (to your car and wallet). Yes - buying from the Dealer is more expensive ; Yes - paying for anti-freeze that is already diluted to a 50/50 mix (as Dealers often sell) pisses me off as a waste of money - but in the big scheme of things you know you're getting exactly the correct fluid recommended by the manufacturer. And the Parts Guy will gladly tell you the correct amount to buy and even recommend "extra" stuff like gaskets.

The fact you are unsure of the cooling system capacity (did you look at your owner's manual) and unsure of the mix ratio tells me you may be new to auto maintenance. Please Understand - I'm not criticizing here (it's great you want to do this yourself - so few people have any such skills these days) -- my main point is that you have no room to make a mistake - you must be 100% correct with fluid replacements.
 

Fred930

Scirocco MK II Track Car
Location
Wisconsin
Oh - I forgot the main point .... You need to determine why you are getting a "flashing" light on start-up before wasting a lot of time and money replacing your coolant (which is probably rated for many years of service). If you install new coolant, THEN determine you need a new thermostat or water pump - you will be buying MORE coolant after the replacement.

Of course - I'm assuming for now that you have checked the coolant reservoir and it's at the proper "Hot - Cold" level.
 

707Stang

I'm Hella From Nor*Cal
Location
Nor*Cal
All of a sudden I'm getting the thermometer flashing light on start up, not every time but just every now and then, winter is coming, and I'm thinking of just flushing the system. For those who have done this, do you run anything in your system before draining the coolant?



I have the factory coolant already, is it a 50/50 mix? I don't want to burn up my water pump with straight coolant. What is the radiator capacity, will one gallon of coolant be enough? Thanks all.


The factory bottle of coolant you buy is undiluted, so yes mix it with distilled water. As others have said, have you checked the level? You may not need to do a flush, although it’s never a bad idea, if the cause of the light isn’t coolant related.


Sent from my iPhone using Tapatalk
 

3carmonte

Gelbrain
Location
Seminole, FL
All of a sudden I'm getting the thermometer flashing light on start up, not every time but just every now and then, winter is coming, and I'm thinking of just flushing the system. For those who have done this, do you run anything in your system before draining the coolant?

I have the factory coolant already, is it a 50/50 mix? I don't want to burn up my water pump with straight coolant. What is the radiator capacity, will one gallon of coolant be enough? Thanks all.
If you have the factory coolant already, (Part No. G 013A8J1G) Read the directions. The system capacity is in the owners manual. The mixture directions are 50/50 but not more than 70/30. They recommend draining the existing fluid and then flushing the system by re-filling with soft/de-ionized (distilled) water and running in until warmed-up then draining. Don't forget to open the heater all the way to flush the core. Repeat until it drains clear. From my experience (with other vehicles however), three flushes will do it. Be aware that unless you are able to drain the system completely, there will still be some clean distilled water trapped in the block and other places. This must be considered in your final mixture calculations. So, subtract measured system coolant that drains out from the rated system capacity (owners manual) and when you refill, take half of that remainder and substitute that amount with pure coolant when preparing your final 50/50 mix. This should get you pretty close to where you need to be. *Don't forget to drain, clean and refill the reservoir bottle as well. Two gallons of coolant (you will have 1/2 gal left over). And at least 6 or 7 gallons of distilled water from the grocery store/Walmart should do it. RE: FRED930: Find the fault causing the symptom before blindly burning money on a coolant system flush. See what codes the ECM is throwing first would be a way to start. Good Luck!
P.S. What is your mileage? Are you do for "the big one"? (Timing, drive belt, pulleys, Thermostat etc.)? Your car is talking to you. Listen. :biggrin:
 

3carmonte

Gelbrain
Location
Seminole, FL
Why would you need to do this on a MK5 seeing that they do not have a heater control valve.
odanny's Avitar text is "2008 Rabbit" which I am not familiar with. Just trying to cover all of the bases. I just learned about the heater core's output by flap control myself not long ago!
 

odanny

New member
Location
Illinois
Thank you all for your replies, this forum is by far the best VW forum with the most educated and helpful members of any on the internet.

I get a flashing thermometer on startup, it is preceded by three loud beeps. I do not have a check engine light. My bottle of VW coolant does say that it should be a 50/50 mix, and no stronger than a 70/30 mix. I'm not running hot, either. I am low on coolant and it's time for me to drain the original coolant out and replace with new before winter.

The engine has 104K completely trouble free miles on it, car has been amazing in the 6 years I've owned it. But it is due now for the timing belt replacement, which I plan on doing sometime. I just need tp make sure I get the mixture right and don't add too much water, to too much coolant. I'll probably just pre-mix everything, then I won't have to worry about it.
 

vwengineer

Ready to race!
Location
Switzerland
The problem is that if you do a flush, you will not be able to recover all the water, therefore it will inevitably mix with the coolant you add. Thats the reason why you should still take it into account in your mixing ratio
 

Oxidizer

New member
Location
Russia Moscow
If the flushing is done on a special installation, then the replacement occurs by replacement. Old fluid is pumped out, new fluid is pumped. Mixing is minimal. The freezing temperature of the liquid is not affected.
He may live in California. You can fill the water. Coolant is usually checked by a refractometer. If necessary, concentrate or water is added.
 

odanny

New member
Location
Illinois
Thanks again all, I just added coolant to the system, since it will need a new belt and water pump soon, no point in flushing the system. The VW coolant says it should be a 50/50 mix, and that you can not go any higher than a 70/30 mixture.
 
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