been there man. you actually helped me with mine

 

I remember. You're not a man till you've stripped your dash down to the firewall right Elduderino?

 

Ha! Well I wouldn't say that specifically, but I would say not until a certain amount of blood sweat and tears goes into your car. Which, of course, the heater core replacement does supply.

 

So yesterday I did most of my heater core job. I have to put the center console together today, but it's at least driveable again (meaning I have a steering wheel).

This first pic shows the clogged heater core with the top torn off. Doesn't look that bad does it?

Check the second pic. The factory Behr heater core had these little spiral things in the passages to create turbulence. Pulled them out with a needle nose and they are clogged. I must have flushed this thing at least 50 times both directions. Now I know why I never got it clean.

 

Nice disection and for sure a reason why.
But this G12 coolant is most likely only slightly better than GM dexcool if not the same. They had a class action suit over this junk.
I suspect it survives as well as it does in our audi due to better quality materials ( blocks, heads etc.)
Mercedes used in every similar (oat) but found issues and started to recommend 3 yr servicing. I believe there may be some electrolysis starting to happen over time that crystallizes the plastic like your fittings did.
I may be way off or wrong on the cause - but I do believe consistent service will prolong the lifespan.

 

It's interesting, all that pink stuff in the spirals? When I looked at it the next day it was all white. White in the plastic top too. Your theory about flushing/new fluid might be a good one. I'm not a chemist at all, but the stuff looked like calcium.

 

It makes you wonder if you should do a routine heater core flushing every couple of years. Shoot some clean H20 through there to break loose some of that crap.

I mean I know you're supposed to change the coolant every so often but I'm gonna think about specifically looping off the heater core and really giving it extra attention next time I flush the cooling. A good couple of times in both directions to really knock that stuff off.

 

I wonder if this is caused by people using tap water rather than distilled water to dilute the coolant.

 

I'm one of those people bshusted. I've read the distilled water thing is a myth, and my Bentley doesn't mention it. What do you know?

 

If you're looking for a source of mineral deposits, tap water is full of them. I'm not saying that is the cause, but it makes me wonder. I've always used gallon jugs of distilled water to dilute my coolant.

Do you know anyone with access to a spectrometer? It would be interesting to get a sample of the residue analyzed for its contents.