I own a 2015 Q3 with c.40k miles on it. Purchased a year ago from Audi. The car recently overheated. Upon inspection, I found two small canisters IN the coolant tank with small granules in the canisters. One of the canisters had broken open so I assumed that the granules were now in my coolant system. The mechanic had to replace the water pump and thermostat due to both a leak and clogging by the granules. Our assumption was that the canisters/granules were a cheap fix for an existing leak, prior to my purchase. 

I spoke to my Audi dealership and they told me that the canisters are normal and that Audi put them in ALL their coolant tanks! No one I have spoken to and none of my research has found anything about these canisters. 

Does anyone here know anything about these mysterious canisters that I found in my coolant tank and if Audi do actually put them in, and why?!

I've never heard of this. Might be worth your mechanic taking nthe system apart, getting the cannisters out to see if they have an Audi part number. If they don't have an Audi part number then I'd say something isnt right 

@Steve Q Already checked. No identifiable Audi markings or reference numbers on the canisters. They’ve been removed as we suspected they were the likely cause of the water pump failure. Can’t find anything confirming that these canisters are Audi’s apart from the dealership claiming it’s ‘normal’. Doesn’t sound right to me. 

Hello Kurt,

As with Steve,I had never heard of this before - before some one mentioned this on a forum post (last year?). I’m sure Steve with his much younger brain will locate it for you! 

Why a bag of granules?? Would it be possible to get a ‘why statement’ from Audi?

Kind regards,

Gareth. 

@Magnet yes, waiting to speak to the manager to find out why they put these in the tank. It seems to me like an additive of some sort, but can’t find anything about it online and I’ve spoke to several mechanics, and none have heard or seen of this before. Will let you know what Audi say. 

Hello Kurt,

I think the full answer rests with Audi UK, rather than an individual employee’s interpretation of the fact. Worth trying an e-mail to Audi Customer Services regarding its purpose an an ‘additive’ to the coolant fluid, and equally important, the resultant problems when the ‘container’ fractures, and who pays for the resultant issues. 

Kind regards,

Gareth. 

I agree with Gareth, Audi uk needs to be contacted. This isn't normal. If it were done by Audi, the cannisters would have a part number and would be easily ordered from a parts department. If there's no part number it cannot be ordered. 

Surely fitting something to s coolant system which can cause failure to other components is not logical. 

Thanks Steve, but even my ageing memory points me to recall someone else on here found a bag/bags of granules suspended in the coolant reservoir and was assured that it was then the norm.

Why? I really can’t recall that answer - so over to your younger brain Steve! 

Canister as opposed to ‘bag’?? 

Kind regards,

Gareth. 

 

Couldn't find it in the forum, but found this: 

https://forums.ross-tech.com/index.php?threads/8529/

Allegedly this is the purpose: 

(Still should have a part number though surely!)

"Coolant Expansion Tank with Silicate Repository

The coolant expansion tank contains a silicate repository. Silicate is used to protect the aluminum components in the coolant
system from corrosion. There are silicates in the G13 coolant, but they are used up over time if the engine is subject to high
thermal loads.
To compensate for the silicate consumption, silicate is taken from the repository and added to the coolant. The silicate
repository provides additional protection against corrosion for the aluminum components in the coolant system over the entire
lifespan of the engine."

That’s Steve,

It is there somewhere - complete with a photo as I recall. 

Silicates and lifespan of the engine?

So we have gone from glycol, the whole OAT coolant spectrum and now into ‘coolant for life?? OK it was initially recommended that AOT coolant was replaced every 5 years, but in reality it seldom was, and still did service up to 10 years later. 

Now we are into silicate additives eh? My simple brain points me to ask:- is this little bag (or canister) of tricks adds silicate over time, why not simply increase the silicate level from day one to accommodate the so called loss over time? Hopefully someone will explain the technicalities! 

OK, apparently plus side to this. Downside - the ‘container’ breaks up and deposits crystals throughout the system. Bit of a bummer?? 

Its supposedly called progress.

Kind regards,

Gareth.

Think its a case of a cheap engineering bodge for a poor design maybe?