When to replace the coolant?

[buyingconstant7]

So I know VW claims their coolant is good for the life of the vehicle, but so did GM and DexKill and we all know how that went down.....When should I flush the cooling system and put new stuff in? Mom took over my 2013 Jetta TDI as I got a 2017 Golf R, so she wants to put a million miles on it and wants to maintain it by the book, so we already did a brake fluid flush on it and are doing fuel filters, air filters, etc. at the proper intervals, but what about coolant?

 

[IndigoBlueWagon]

To my knowledge VW does not recommend a coolant flush. When you replace the timing belt and water pump you replace at least half the coolant. That seems to suffice.

I've got two cars here, one with 285K and the other with 325K (miles) and neither has ever had a coolant flush, at least not to my knowledge.

 

[meerschm]

give the coolant a close look for color change and stuff in the bottle.

some cars have had issues with the original coolant fill precipitating stuff that clogs the heater core.

if it is fine, no worries, but if not, ....

 

[IndigoBlueWagon]

If you're implying that coolant can cause heater core clogging, I haven't heard of that. NMS Passats have had heater cores clog because the cores were incorrectly manufactured.

 

[meerschm]

if it is not in the coolant, not sure where it would come from. (if precipitate of some kind did not come out of solution, even the passats would not have any problems)



couple folks have had issues with 2009 jetta heater cores getting clogged up.


http://forums.tdiclub.com/showpost.php?p=5202317&postcount=23

http://forums.tdiclub.com/showpost.php?p=4933052&postcount=7

http://forums.tdiclub.com/showpost.php?p=4633463&postcount=36

 

[IndigoBlueWagon]

What I've heard is that the NMS Passats had too much flux (or whatever you use to put a core together) in the cores, and it came loose and clogged the cores. But I don't think the issue is the same with other models. So perhaps something is going on.

Odd, as people have had relatively few heater core problems on older cars.

 

[meerschm]

could have been just a few 2009 cars...

I think the advice is still sound to look at the coolant, and if it seems close to the original color, and does not have any little bits floating about, replace half when the timing belt is done,

and if it looks rusty or has chunks floating, change it out.

 

[pdq import repair]

My 09 core plugged at 150K. I did a timing belt on it a 120K and the coolant looked like crap then. Changed it at that time, or at least what came out.

Did heater core last week and coolant still does not look good and core had lots of chunks in it that look like solidified coolant. Plan to flush the system and refill with new g13 mix as soon as the weather warms a little.

I agree, as soon as the coolant changes color, change it. Or at least every 100K.

 

[jonferns]

Agree on the issue with the '09s. Had one here (nearing 200k) with coolant 'gunk' throughout the system. Had the head off for repair, had to use pipe cleaner rods and a shop vac to clean all the passages in the block as they were packed with the gunk. OEM coolant used throughout the life of the car.

Haven't seen anything like that on either of my '06s (130k & 220k), or '03 (nearing 400k, coolant never flushed). I haven't had to open the cooling system on my JSW, but the reservoir looks clean.

To the others who have seen this same thing, have those vehicles been DSG?

 

[Henrick]

A good generic guide is here: https://www.youtube.com/watch?v=mHTM3dvpD1M
That guy has got some more great videos, e.g. on how to flush your cooling system, how to flush heater core, etc.

 

[skinnyb]

I would say the advice that IndigoBlueWagon gave is solid. When the timing belt is done at 120k (or 130K on the older cars) just ask the mechanic to finish draining the system and refill when doing the belt, water pump and all the required bits...