Blue coolant contaminated, turns black. Fixed

My 1.4 HDI coolant started changing from clear blue to a murky dark green with black bits from 2 years old. 3 years on and 2 flushes the coolant level started going down and oil level increased as well. Having had similar coolant contamination on my older Peugeot 2.0 HDI from engine oil, I replaced the pancake shaped oil cooler. All seems good 6 months on. Have now pressure tested the old oil cooler and all seems good, Think the problem is down to pitting/corrosion of the sealing ring supports contacting the cooler inlet/outlet areas as seen in attached photo. Has anyone seen a fix for this or will I have to do this again in 2 years time?

Xantia2000 wrote: ↑Fri Dec 11, 2020 8:08 pm My 1.4 HDI coolant started changing from clear blue to a murky dark green with black bits from 2 years old. 3 years on and 2 flushes the coolant level started going down and oil level increased as well. Having had similar coolant contamination on my older Peugeot 2.0 HDI from engine oil, I replaced the pancake shaped oil cooler. All seems good 6 months on. Have now pressure tested the old oil cooler and all seems good, Think the problem is down to pitting/corrosion of the sealing ring supports contacting the cooler inlet/outlet areas as seen in attached photo. Has anyone seen a fix for this or will I have to do this again in 2 years time?

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Someone has used the wrong coolant, one without the correct corrosion inhibitors.

If you find a C3 with blue antifreeze in, don't buy it. The car has been abused.

Fill with the pink OAT coolant for a long life protection from corrosion.

I suggest you read this article from an antifreeze manufacturer. There are historical differences beteen different types of antifreeze, but according to the article antifreeze can be any colour the manufacturer wishes it to be.

https://www.holtsauto.com/prestone/news ... nt-colours

Two quotes from the website.

“That’s why it’s so confusing – you can open up the bonnet of a new car and have no idea what the coolant is based on. Similarly, if you buy a second-hand car, the colour of the coolant gives you no idea as to when it needs to be changed."

“For example, say you buy a second-hand car and it has pink coolant in it. You can see from the service record that it has had a coolant service within the last two years. But is it aftermarket or OEM spec? Will it last for two years or longer?"

Hi, Thanks for you replies and it seems from your information the recommended coolant for the C3 has changed. I have always used PSA PRO 9735K4 as recommended by my old copy Citroen Service Box. I think this is a long life Ethylene Glycol antifreeze and is Blue in colour. I have used it on all my past Citroens with no problems. The only time I used pink OAT coolant was in my mothers C1 3 cylinder which is a PSA/Toyota engine cooling system.
I still think the problem I have is down to corrosion from the contact areas of coolant/oil seal supports against the pancake oil cooler creeping under their sealing faces.
Regards ,
Xantia