Oil in Coolant B4 1Z: Causes & Fixes

Hello everyone,
I need advice regarding the following problem with my Audi 80B4, manufactured in 10/93, with 131,000 km (approximately 81,000 miles), engine code 1Z: At 125,000 km, there was engine oil in the cooling system and coolant loss – about 1 liter per 1,000 km. I then replaced the oil cooler, which successfully stopped the coolant loss. However, there is still a persistent oil film in the expansion tank. I have to remove it every Saturday, approximately every 900 km, but 300 km later, oil droplets reappear on the water surface, and after 3-4 days, the expansion tank is completely soaked with oil again.
I'm now interested in whether there's a type of contrast agent that could be used to detect engine oil potentially entering the cooling system. Please understand that I'm postponing the head gasket replacement for now, as it's still just a suspicion. The problem appeared at 125,000 km, as described above. I bought the car at 100,000 km and have always been very careful and conscientious about warming it up properly. If the head wasn't cracked at 100,000 km, and the head gasket was still in good condition up to that point, I can't understand how my driving style could have damaged it. According to the gauge, the water temperature has never exceeded 110°C.

thank you very much

Hello, the contrast agent you're looking for is manufactured by TRACER. A similar product is often used in air conditioning systems. Ask a technician if they have a TRACER product catalog, as it might contain something similar.

Good luck.

Hi,

Could it be that there are still oil residues on the surfaces in the engine that are gradually being washed into your expansion tank?
How about simply pouring a cup of calcium chloride into the cooling water and then changing the water after a week?
Then the dirt should be dissolved and removed.


Regards,

Eike.

Hi,

I can only confirm what Eike says. When I changed my head gasket, a surge of oil came into the coolant system -> it takes a few weeks for everything to drain out. So, occasionally, dip an old towel into the container (oil floats on water and sticks well to cotton), and after a few weeks, it will be fine.

Best regards, Christian.