bobt Posted July 25, 2006 Share Posted July 25, 2006 I've had my 2000 superlight for a a little over a month now. Now I know the car has been looked after well and the service history stamps verify this. One of the first things I noticed while poking about was that the coolant was errrrh brown ! As I was going to replace the stat for a 82 deg anyway now was a good time to do it. I drain the system and all the hoses have a thin brown slime coating the interior. I pushed water through the system until it flowed clean (didn't clean all the hoses) drained again then refilled with the correct coolant. So now he system is filled with purple liquid :o). However after a month of usage it has gone brown again. Not as bad as before, you can still just make out its abit purple but mostly brown. Is this normal ? What is the brown slime? The engine appears in good health with all temperatures and fluid levels remaining stable. Does this happen to anyone else ? How long does your coolant usually remain its original colour for ? am I worrying for nothing and basically just need t give the coolant system a good flushing with something other than just plain water ? Thanks Rob Link to comment Share on other sites More sharing options...
bobt Posted July 25, 2006 Author Share Posted July 25, 2006 I should add that the brown stuff in no way can be described as oily. Link to comment Share on other sites More sharing options...
CageyH Posted July 25, 2006 Share Posted July 25, 2006 What coolant did you use? Link to comment Share on other sites More sharing options...
bobt Posted July 26, 2006 Author Share Posted July 26, 2006 Mobile Advanced Coolant. Its a concentrate which is then diluted to 3 part water 1 part mobil coolant. Link to comment Share on other sites More sharing options...
CageyH Posted July 26, 2006 Share Posted July 26, 2006 It could be that you had a G11 based coolant before, and have refilled with a G12, without the system being thoroughly flushed. I found this on the web, although it applies to VW, I am sure that the same van be said for a k series engine. "VW recommends the water and compressed air treatment to upgrade to G12 because up to a third of the coolant is still trapped in the heater core and the engine after you pull a hose or the drain cock. This flush ensures that you are removing all accumulated rust, scale, silicate buildup and old coolant as best as possible. By the way, the blue and red coolant will foam up and turn brown in your expansion tank if you mix them or don't get all the G11 out. The degree of corrosion that takes place in your VW depends upon the type of minerals and alloys in the engine and radiator, and the acidity or alkalinity of the coolant. So long as your coolant remains alkaline, corrosion will be held to a minimum. " Link to comment Share on other sites More sharing options...
bobt Posted July 26, 2006 Author Share Posted July 26, 2006 So whats a good way to flush a system them ? With the rad and stat disconnected a pushed water through with a hose pipe until it ran clear. I noticed this did not remove the covering from the inside of the pipes and presumable the engine. Rob Link to comment Share on other sites More sharing options...
CageyH Posted July 26, 2006 Share Posted July 26, 2006 Did you flush the rad, and heater (if you have one?) I would use the hose pipe technique myself, much as you have done. Link to comment Share on other sites More sharing options...
CageyH Posted July 26, 2006 Share Posted July 26, 2006 Big question was what was in it before? Any ideas? Link to comment Share on other sites More sharing options...
bobt Posted July 26, 2006 Author Share Posted July 26, 2006 No idea what the last coolant was I'm afraid. The car does not have a heater and I fitted a new radtec rad at the same time as changing the coolant so I know that was clean. I'm hoping the new brown coolant is just being caused by some left over crap and gunk for the insides of the block and pipes rather than anything more sinister ☹️ Rob Link to comment Share on other sites More sharing options...
CageyH Posted July 26, 2006 Share Posted July 26, 2006 It does not sound that sinister if it is not oily. Link to comment Share on other sites More sharing options...
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