Black sludge in coolant tank!

[Aleung2]

Hi everyone, I've only had my car about 6 months. It's a 2.0 tdi cr170 with 35k miles. It was bought from audi at 20k who did a service before it was sold to me. Anyway, admittedly I haven't checked the oil level and now the oil level warning came on so I've checked that and topped it up. I was surprised that its used so much oil in 6 month with virtually all motorway miles.

Anyway my 2nd worry is that the coolant light came on too so when I checked that it was full but had a thick layer of black sludge on top like its engine oil. The tank looks very murky too, which looks unusual.

This leads me to my 3rd worry..... Do I have engine oil leaking into the coolant somehow and that's how I've used so much oil?

From threads on here it doesn't seem that common but the ones who had mentioned that the leak probably came from a leak in the oil cooler. I didn't even know I had one actually.

Ill be taking it back to audi but has anyone else had this before, if so, what was the problem? Forgot to say that the temperature is fine by the way. Thanks.

[Doctle Odd]

Sounds like your oil cooler has fractured. It will need flushed and cleaned and the oil cooler replaced

[MarkTM]

^^^ After that most likely your coolant will need to be emptied/flushed/replaced again to ensure no oil's left in it.

That said a complete new coolant tank's only about £18+VAT

[Doctle Odd]

It's an easy DIY job. As Mark says you'll need need new coolant. A handful of Daz washing powder (Mrs Odd uses Daz) and an hour. You can buy various types of flushing agents but the washing powder works great.

[Aleung2]

Ah good, I'm glad its easily diagnosable and doesnt damage engine or anything then. Its under warranty anyway so I'm not expecting to pay a thing. I've got a list of things they can sort out too whilst I'm at it.

Thanks guys, much appreciated.

[Doctle Odd]

I'd get it sorted as soon as possible mate, oil in the heater matrix and radiator is never a good idea.

Ah good, I'm glad its easily diagnosable and doesnt damage engine or anything then. Its under warranty anyway so I'm not expecting to pay a thing. I've got a list of things they can sort out too whilst I'm at it.

Thanks guys, much appreciated.

[gupsterg]

As the oil can end up where the coolant should be, the coolant can end up where the oil should be ... I'd x2 on Doc's comment on ASAP remedial work of fault ...

[Aleung2]

I agree, water in the engine is never good! I called Audi and they said call audi assist right away so I did. They're coming to collect car as we speak. Cheers everyone

[Aleung2]

Bit of an update on this. The technician reckons its the oil cooler too and he mentioned that water shouldn't go into the oil because the oil pressure is greater than the water is it should only go one way. It's bank holiday weekend so I'm stuck with a brand new a5 s line for the next few days instead.....could have been worse eh

[Aleung2]

Final update on this guys. It was as you suspected the oil cooler which failed seeping oil into the coolant. Audi has replaced the same and flushed the coolant 4 times. I asked them about the possibility of coolant getting into the oil when the pressures equalise when the engine is off. He said it was unlikely and if it did then it would emulsify in the oil and you'd see it on the dipstick.

Anyway, the car is back and I've given the nice a5 back to them. Missed my car but I actually really miss the auto of the a5 too lol