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Brown Slime in New Cooling System
Irony - 15/9/14 at 04:38 PM

Been working on my car for years and I finished the cooling system a couple of years back and filled it up with coolant and antifreeze etc. Now the engines running the cooling system is working as it should. I have decided to change the thermostat for a lower temp one. On draining the system the inside of the pipes are coated with a brown residue, Its on the silicone hoses, the insides of the aluminium pipes and when you open the radiator you can see it on the fins. It's not the sort of brown you get from a oil/water mix, it's the rich red brown of rust. Theres no evidence of oil in the water so I doubt its the head gasket. I also seem to remember mixing red and blue antifreeze when I filled the system. I just thought they were the same product at the time. I didn't know any better.


Anyone have any ideas how this has happened? What is it? Is it normal? How can I flush it all out?



[Edited on 15/9/14 by Irony]


sprouts-car - 15/9/14 at 05:00 PM

I wasn't aware of this, but after some googling, it seems that brown sludge is what you commonly get when you mix antifreezes.

For example: https://uk.answers.yahoo.com/question/index?qid=20100110042919AAfrIjY


Slimy38 - 15/9/14 at 06:13 PM

Not mixing red and blue is one thing that all VW owners should be warned about. I've lost count of how many forum posts I've seen where sludge is encountered because someone topped up their stock VW coolant (blue) with cheap supermarket stuff (red). The usual response is 'it was fine with my last car'... probably because the last car also used the red stuff!

It does sound like you've caught it in time before it completely blocks something up. I'd just blast each section with a hosepipe until it runs clear.


rusty nuts - 15/9/14 at 07:23 PM

If you can find some a couple of cans of Forte Bio degreaser in the cooling system will help flush it out


britishtrident - 15/9/14 at 07:44 PM

Nasty German bio degradable antifreeze flush it through an put proper red OAT longlife coolant in.


britishtrident - 15/9/14 at 08:03 PM

quote:
Originally posted by sprouts-car
I wasn't aware of this, but after some googling, it seems that brown sludge is what you commonly get when you mix antifreezes.

For example: https://uk.answers.yahoo.com/question/index?qid=20100110042919AAfrIjY


US made Prestone anti-freeze was sold decades back in Europe it never caught on, before mixing it was red viscous and sticky and never caught in the UK.
Another antifreeze with a similar stick viscose nature was Blucol AAA was specified for the first Hillman Imps and it caused problems with blocked radiator tubes.


nick205 - 15/9/14 at 08:05 PM

quote:
Originally posted by Slimy38
Not mixing red and blue is one thing that all VW owners should be warned about. I've lost count of how many forum posts I've seen where sludge is encountered because someone topped up their stock VW coolant (blue) with cheap supermarket stuff (red). The usual response is 'it was fine with my last car'... probably because the last car also used the red stuff!

It does sound like you've caught it in time before it completely blocks something up. I'd just blast each section with a hosepipe until it runs clear.



The 4 VAG cars I've owned and 3 I've serviced have always run the stock pink coolant. If you buy VAG OEM or aftermarket VAG spec'd coolant it's also pink. Last time I looked in Halfords, their non specific coolant was blue.


Slimy38 - 15/9/14 at 08:46 PM

quote:
Originally posted by nick205
quote:
Originally posted by Slimy38
Not mixing red and blue is one thing that all VW owners should be warned about. I've lost count of how many forum posts I've seen where sludge is encountered because someone topped up their stock VW coolant (blue) with cheap supermarket stuff (red). The usual response is 'it was fine with my last car'... probably because the last car also used the red stuff!

It does sound like you've caught it in time before it completely blocks something up. I'd just blast each section with a hosepipe until it runs clear.



The 4 VAG cars I've owned and 3 I've serviced have always run the stock pink coolant. If you buy VAG OEM or aftermarket VAG spec'd coolant it's also pink. Last time I looked in Halfords, their non specific coolant was blue.


B*gger, I knew I'd get those colours the wrong way round, serves me right for doing it from memory. It was the G12 coolant that I was thinking of, when it's topped up with 'standard' coolant it turns to sludge.


Irony - 16/9/14 at 03:54 PM

Oooof, that Forte Bio Degreaser is expensive! £15 for a bottle. Can anyone recommend a slightly more locost product?


britishtrident - 16/9/14 at 06:44 PM

You can use a small amount of non foaming detergent (dishwasher powder) to remove oily depoists but you must follow with a cold water flush then an acidic flush ie. citric acid solution as used for kettle descaling, then reverse water flush.

[Edited on 16/9/14 by britishtrident]