1999 Passat 1.8 Sport Petrol: Coolant flush query ...

[JulianHicks]

I've had my Passat since I bought it from a dealer ex-lease in 2002. It was high mileage (105,000) but in good condition and with a complete detailed service history from the leasing company.

It has served me well for almost 5 years and has now reached 181,000 but it's always had an intriguing coolant problem!

I'm after advice on flushing the cooling system since it's had some brown contaminant since I owned it. The plastic fill bottle was opaque so I had it replaced, but it still seems to have the brown stuff slowly shifted round the cooling system and into the bottle, leaving a fine layer I can wipe with my finger!

Can someone suggest what I should try for flushing this out please? [I can't seem to find any official VW solution and I've heard about washing up liquid or soap powder as possible answers]!

PS I suspect it was caused by the previous driver who tried something off his own back, since there's no mention of any cooling parts or problems on the leasing company's extensive service and repair list!

Thanks - Julian

[Lex Luthor]

When I bought my ADR the previous owner had topped up the coolant with regular glycol stuff which had precipitated a brown gunge.
I replaced the expansion tank as it could not be cleaned, reverse flushed with a hose till everything ran clear, then refilled with 50% G12.
Its been fine ever since.
I think you might be leaking a little oil into the water.
The usual source is a failure of an O-ring in the oil cooler. This is quite common in the forums and is easy and cheap to fix.

[Gurdeep]

hi i have a 2000 1.8 and there is contamination of the coolant as well i have been told by the previous owner that the oil cooler was changed. How can i flush the system i am a novice mechanic will i have to remove the lower shields to get access to the lower rad pipe or is there a easier way also what is G12? thanks in advance

[Crasher]

Don't laugh but I have found the only way to shift oil out of the cooling system is with Flash mixed 50/50 with water. G12 is the old spec now, we have shifted over to G12+ which doesn’t leave a reddy brown silt layer in the system and can mix with conventional coolant types should that be unavoidable or should it happen by error.