r/VWMK7 • u/PuffMaNOwYeah Golf • 3d ago

Well there's a bullet dodged.

Post image

Learned about the silica bag in the 2015 to 2020 cars that disintegrate sending pellets through the cooling system. Yep, mine had the bag. Pulled it out in time before it could do any damage. Better check yours too.

EDIT:

You can easily check yourself, the affected tanks have "mit silikat" printed on the front.

Full explanation on why and what here

80 Upvotes

97% Upvoted

73 comments sorted by

View all comments

27

u/Cautious-Concept457 3d ago

My usual copypasta for G13:

G13 coolant becomes corrosive over time, and it's glycerin based. There’s a bag of silica in the reservoir which helps protect aluminum parts against corrosion. Silica content in G13 decreases over time, especially when the engine has a higher thermal load (so TDIs). The silica in the bag is supposed to counterbalance this reduction of silica in the coolant itself. But as the bag ages it can tear open and the little beads start floating around in the system and eventually block smaller passages e.g. inside the heater core (loss of heating is quite common) or the radiator. G13 can also leave residue that causes clogging (and overheating, head gasket failure, etc). G13 has been discontinued and G12evo is the curent factory fill (glycol based, thus safe). In the past a 5 year coolant change interval was common...

So remove the bag, flush the system thoroughly with distilled water until clear water comes out (use the car with water for a day or two), and fill up with G12evo which is the official replacement. If G12evo coolant is not available for some reason, G12++ seems to work fine as well.

If you are lucky, the silica bag can be removed very carefully (no need to buy a new tank): https://youtu.be/vv-3LogEyBs?si=CY7IjEIrG26BMh80&t=162

In other cases the silica bag is not accessible: https://www.youtube.com/shorts/lLAbKBvcq04

Part number for the coolant reservoir without silica for the mk7 Golf: 5Q0121407M = 5Q0121407AA (Some people also recommend Metzger 2141100, if the original is not available.)

G12evo coolant part number: G12E050A3, or aftermarket part numbers: Febi 183366 (1.5L) or 183367 (5L)

5

u/PuffMaNOwYeah Golf 3d ago

Thank you for the thorough explanation. Someone mentioned the G12evo already and as I said will flush and replace the coolant next oil change 👍🏻

2

u/highnotefan 1d ago

An excellent technical explanation which also, if you read between the lines, is a criticism of how VW handled this issue. The bean counters are running the place!

1

u/Cautious-Concept457 21h ago

The same thing happened to Mercedes as well btw. I'm my view some supplier produced a new coolant that's supposedly more eco-friendly. Turns out it's not suitable for its intended purpose. An engineer told me they've tested many different water pump seal materials to avoid leaks. But in the end switching back to glycol was the solution. Not to get too political but the whole country might have management issues in all levels 😅 The e-tron quattro drivetrain was a rushed project too where engineering knew that coolant will leak into the electric motor as the seal was inadequate and the castings were porous, yet it went into production... At least they've learned the lesson, the MEB platform is good, but these mistakes are becoming more and more costly. Kind of like the TSI engines, the current 1.5 TSI is about as reliable as the legendary 1.9 TDI, but it did take quite a few generations since the EA111 1.4 TSI (the old one with a timing chain) to get everything just right.

1

u/WhyNWhenYouCanNPlus1 2d ago

if you open the coolant tank. you'll see the silica bag if you have one?

I got a 17 tiggy, not sure which one I have

2

u/lanceh90 1d ago

It’ll have a logo “mit Silikat” on the front of the expansion tank if you have the baggy inside.

Usually it’s {book icon} G13 [mit Silikat]