It all started as outlined in the "Pointers,Please" thread, doing timing chain and other stuff.
All back together, my daughter headed to class and in a few miles the cooling system had a melt down. She knew something was amiss as the heater was not warming so she was alert for trouble. Started noticing the smell of coolant then the light came on. At a gas station and steam coming out everywhere. shut it down and called me.
It didn't get super-hot. I got there and looked it over, tried refilling coolant, capping and run a bit, all seems dandy for a few minutes; of course, there's no temp gauge to show impending overheat. After running four or five minutes, there is a *sudden* release of steam from behind the engine and at the same time, the coolant reservoir starts belching coolant through the relief in the cap, dumping this coolant directly into the path of the fan which then throws this coolant around and behind the engine, making a mockery of my efforts to see what/where it's all coming from. Shut it down, left it to chill, later got it back to the shop to investigate.
I have read of course, all the reports of thermostat housings cracking and water pipes bursting. Note that before the TC job there were NO cooling system issues except for the complaint the little car took too long to warm up. There were NO LEAKS anywhere before this work.
During the TC job I didn't disturb any of the coolant stuff except that I did change the water pump. I inspected the water pipe at that time, it looked OK.
So, now, back at the shop I;ve already ordered in the thermostat housing and the pipe, just because. It is evident around these interwebs that these pieces need to be changed regardless their current culpability in this event.
Because I *wanted to see* what was happening rather than just yanking it all out, I pulled the intake manifold to get a good look at the water pipe.
What I could see was that without a doubt, the pipe had failed and was leaking a lot.

The thermostat housing, on the other hand had NO cracks and NO leaks.... but after removal i found a failure mode that no-one had mentioned anywhere in all my searching of the internet; the interior of the housing had *ERODED away*(!)

The thermostat was likely not fully closing because the plastic that should be supporting its base was *GONE*. Now, when I first pulled this off the car I had never seen one of these assemblies so I had no reference for how it SHOULD look, but it was obvious that the thermostat was not properly situated. A day later when the replacement part arrived, I was stunned to see what wasn't there.
The missing piece of plastic was later found to have fallen out, unnoticed and was under the lift.
The water pipe that was good two days ago was now missing its end and the o-ring support. These pieces and the o-ring were in the water pump impeller.
New pipe, new thermostat housing, new MINI blue coolant and she's back on the road.
The car's is fine now, no cooling issues, the heater now works. Ity still has some VANOS issues....for another day.

Contemplating what we've seen and learned:
History: 2013: daughter #2 ran over a critter, destroying the radiator. I replaced it with new and some extended-life coolant but I don't recall the brand. It was not MINI brand.
Dec 2015: daughter #1 inattentively bumps another car while waiting at a traffic light, destroying the radiator. (yes, it's incredibly easy, without even paint damage) I replace with new, filling with DexCool.
The thermostat housing appears to have some strange buildup inside.
Counter-intuitively, it appears that the plastic is massively eroded away.

What caused the erosion?
Has ANYone seen this happen?
Is this a 'known failure'?
Is this why they eventually leak? They just wear through?
Anybody know what the glop is that has built up in there?
When the coolant drained at the service station, it looked like it had gelatin in it. (?)
Any ideas as to why the pipe failed coincidentally to the water pump change?

 

Yikes and wow, I have not seen it that bad, if the coolant was not the MINI Blue or meets MINI Blue Coolant standards and was something else, that would explain some of it. I never seen it that bad, all i can think is it was dexcool or something else put in by mistake. That's why i use the Blue stuff:

https://www.northamericanmotoring.co...8-no-heat.html

I have heard of this when someone used dexcool.


Glad its fixed, but i would flush that old system with cleaner and water as mush as possible, hopefully your rad and heatercore is not clogged like crazy.

 

What caused the erosion?
Has ANYone seen this happen?
*Yes, not that bad though
Is this a 'known failure'?
* Usually see it when the engine overheats,...
Is this why they eventually leak? They just wear through?
*Noooo,.... this is a one in a million case,... like ECS said, never seen it that bad
When the coolant drained at the service station, it looked like it had gelatin in it. (?)
* Yes, propylene glycol coolant (mostly GM and Asian) added to ethylene glycol (MINI coolant)
Any ideas as to why the pipe failed coincidentally to the water pump change?
* Same kind of plastic so same kind of overheating/deformation,... if the water pump is still the plastic kind, expect replacing that soon

 

Thanks.
No the water pump is the metal replacement. So now, the water pump, water pipe and thermo housing are all a week old while the radiator is about three months old
Hopefully the cooling system will be happy for a while.

But wait.... Are you saying that the MINI branded coolant is just "plain old ethylene glycol"?
Then why is it thirty bucks a jug?
Recent reading has taught me that DexCool has a large group of dissenters and "muddy" is an oft-quoted description.
That's why I went with the MINI stuff.

 

Nope, it is ethylene glycol based, (which is the actual "anti-freeze" agent), but contains proprietary additives to prevent corrosion and lubricate the system, those additives are much better at transferring heat, corrosion protection, electrical charging and lubrication than any other "green" coolant out there,...
Hopefully that clarifies it!

 

NEVER ADD DEXCOOL TO A SYSTEM THAT WASN'T DESIGNED FOR IT!!

Never. Ever. Do it. On the flip side, never add standard coolant to a system designed and factory filled with DexCool. Use DexCool only.

If the system isn't 105% clean and new, that stuff causes problems. I've never seen melted components before, but I have seen the gelatinous "mud" coolant that you saw with yours. The PO of my BMW brought it to a shop that "topped it off" with DexCool for some unknown reason. Green coolant turns instantly a muddy brown after over 5 complete system fills and drains. It left reddish brown precipitate in my coolant bottle too. I even stuck a garden hose into the water pump inlet while leaving the drain open once, the insides still aren't entirely clean. It's almost impossible to entirely be rid of the stuff.

 

While the housing of the 2nd Gen water pump may be the updated version with cast metal housing. The internal vanes / components that move the actual coolant are not....

 

As GimmeBoost says, mixing DexCool with any other coolant is a giant no-no. You can end up with a gel-like goo plugging the cooling system. I stopped using DexCool in any and all vehicles years ago, and I do not believe that its use is mandatory in any vehicle, including GM vehicles for which it is the factory fill.

My first thought was: wotinhell was in that coolant, sulphuric acid?????

The deterioration of the thermosat housing is quite dismaying. I don't know how to interpret it, but I suspect that it has something to do with the changes of antifreeze. I will take that as a warning to stick with a BMW/Mini approved antifreeze.

The other factor, but one that I suspect is not as important in this case, is that BMW/Mini recommend only using distilled water with their antifreeze.

Incidentally, Advance Auto parts carries Pentosin Pentofrost NF, a BMW-approved blue colored antifreeze for about $11 per 1.5 liter bottle. This is a readily available coolant and much less expensive than BMW brand. I just picked up two bottles of the stuff for future use, as we have two BMW 3-series and a 2011 Mini in the family.

Based on past experience with German cars, I strongly suspect Pentosin is the actual supplier of coolant to BMW and Mini.

http://www.pentosin.net/f_antifreeze.asp

I clicked the datasheet on the NF and confirmed the BMW part number for the antifreeze: http://www.pentosin.net/specsheets/Pentofrost_NF.pdf

My recommendation - purge the entire cooling system of whatever is in there, wash it out as thoroughly as possible, and refill with a Mini-approved antifreeze and distilled water.

 

Zerex G-05 is also in the same category as the BMW/MINI/VW blue coolant. Gold in color, but completely compatible.

 

I've been trying sort out the cause of the material loss as well. To my eye it looks like erosion, as if the coolant were loaded with silica or other abrasive. It may be chemical sttack that softened the material, leading to erosion.
One weird bit is that while it looks like goo, it *feels* like there's a coating of hardened resin in there. Makes absolutely no sense.

Thanks for the Pentosin tip.
I did try to flush the mess out but couldn't tell if I did any good.

 

dexcool and what ever water was mixed with it, most likely did this, what did you mix with it , tap water or distilled water or straight dexcool.

 

As stated, the radiator has been changed twice due to minor damage. The first time I used an extended-life coolant but I don't recall the brand. Could have been DexCool but not known. The recent replacement (Nov?) I used DexCool.
I have no way of knowing which if any of the mixes might've done the damage, but it certainly is severe. I have to wonder how long it would have been for perforation to occur.
After flushing I refilled with Mini blue and just a small amount of tap water, not a 50/50 mix.

 

MINI Blue / distilled water and I would Mix 50/50, done this on all my MINIs. Tap water has containments and deposits dissolved in it. Dont use dexcool.

 

So nearly straight coolant then? That provides worse heat transfer (cooling), less overboil, and less freeze protection. That ideal mix for overboil and freeze protection is around 70/30 coolant/water IIRC, but 50/50 is close and so much easier to do. Lesser concentrations of coolant actually result in more effective heat transfer.

TL:DR - Don't run straight or nearly straight coolant. It's designed to be diluted with water, and you should do so.

 

I don't see where this is any cheaper than Mini fluid.

 

Cheap isn't the goal. Functional and operating correctly with system-compatible antifreeze is the goal.

 

Well, cheaper is not a bad goal, for certain.
For me, the primary metric is usually *immediate availability*.
It is a fact that MOST Mini owners live in cities that HAVE a Mini dealer.
I don't, in fact the nearest is over two hours away. (BMW, 1 hr)Unless I stock the stuff at home, any unplanned repair work results in using product on hand or local. The Zerex seems like the best local option at this point. The Pentosin (that sounds so pharmaceutical) is pricey but may be readily available.
I won't debate the merits of straight vs diluted coolant. Well established, but nothing to do with the real dilemma here, which is: what caused this dramatic loss of material?
UNrelated: I saw the coolest Clubman today...