I have noticed small black residue gathering on the inside wall of the coolant bottle,any thoughts, head gasket or intercooler maybe ???

I have been suffering fairly bad coolant loss over the last while but I thought I solved it by replacing the coolant feed to the heater matrix and the coolant flange on the right hand side of the head which where both leaking badly, but its still loosing a lot of coolant and the black residue seems to be a new problem.

I will add that the car has just short of 500,000kms on it if that helps with the suggestions. Any ideas greatly appreciated.

not really certain, but IIRC thats a sign of head gasket failure, hopefully Im wrong and hopefully you dont have the well known 2.0 TDI Porous head problem

310,000 miles!

EGR cooler perhaps? Probably worth investigating before suspecting the head or head gasket.

BTW the intercooler is only an air to air heat exchanger and doesn't have any connection with the coolant.

This happened to me when the car was under warranty ,and it turned out to be the oil cooler

I did put a post up but can't find it

Cheers, can you remember if it was a big job??

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not really certain, but IIRC thats a sign of head gasket failure, hopefully Im wrong and hopefully you dont have the well known 2.0 TDI Porous head problem

Daz, I think if I was going to suffer the dreaded Porous Head problem it would have happened some time in the previous 300,000 miles:blink::blink:

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It could still happen any time, but I would look into an EGR removal and that would eliminate it. at 300,000 miles I would say its quite likely coming to the end of its life.

If you suspect oil is getting in to the coolant, is coolant getting in to the oil (mayonnaise on the inside of the oil filler cap)?

At that kind of mileage it could be a hose deteriorating and the black stuff you are seeing is rubber residue??

It could still happen any time, but I would look into an EGR removal and that would eliminate it. at 300,000 miles I would say its quite likely coming to the end of its life.

I think when it does die, I'm going to have to give it a full blown Irish "wake"

It's served me very well.

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If you suspect oil is getting in to the coolant, is coolant getting in to the oil (mayonnaise on the inside of the oil filler cap)?

At that kind of mileage it could be a hose deteriorating and the black stuff you are seeing is rubber residue??

There doesn't seem to be coolant in the oil and I have just replaced a badly corroded hose.

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