Audi S4 2010 3.0 V6 - oil/water mix

[Mo_junz]

Hi Guys

Okay, so..

My bro has a 2010 S4, beautiful car. Shes been out of action for the past 2 months sitting at the workshop. Here's a little thread of the chain of events that occurred and still to no avail she aint fixed.

The car started to lose water, it displayed warning signs to notify that the water is low and needs to be topped up. Water topped up and a few hours later she was thirsty again. This got us worried as we know its not normal and there are no exterior leaks, which was later proven correct when we noticed an oil and water mixture on the oil filler cap.

Off to the workshop, the head was removed, engineered, tested etc, basically the whole top end was redone and fitted back on, car was left to idle for 3 hours no warning signs nada.. Everything seemed perfect. Car was then driven on the road and after 30 mins she displayed the water low warning and basically it meant back to square one. No limp mode nothing car still drives and idles fine. Obviously wasnt driven since the warning lights were displayed. Theres no mixture in the water bottle and now the next thing that will have to be checked will be the block. Now its already been so damn costly and I need advice and information if this has occurred before with someone or maybe the experience on here will assist me in finding a solution.

What are your thoughts guys? Even if you suspect an issue let me know i wanna hear them all lol.

Thanks

[amstel18]

Check if it has an oil cooler. Could be that

[Mo_junz]

oh yes, apparently that was tested and said it was fine as that will cause an oil/water mixture in the reservoir. Thats afaik, please correct me if i am wrong.

[JasonCPT]

oh yes, apparently that was tested and said it was fine as that will cause an oil/water mixture in the reservoir. Thats afaik, please correct me if i am wrong.

Correct.

Have they checked the oil filter housing? The cooler might be fine but the issue could be at the housing itself.

[Mo_junz]

Have they checked the oil filter housing? The cooler might be fine but the issue could be at the housing itself.

Hey Jason, if it was the filter housing, could that cause a mixture in the engine? thanks

[panic-mechanic]

I would simply change the heat exchanger as a point of departure. Not sure how you would test them but anyway.
Did they leak test the cylinder heads?

[Mo_junz]

I would simply change the heat exchanger as a point of departure. Not sure how you would test them but anyway.
Did they leak test the cylinder heads?

Yes panic, the test was done and according to them was perfect. Heat exchanger? please could i have more info? where is it located? Thanks

[panic-mechanic]

oil/water cooler. Should look something like this. Might be mounted between the alternator and the block. I have not really looked at those engines closely in quite a while.

[Mo_junz]

Thanks panic, will definitely get them to have a look at it again and see what they say.