Im currently 300miles in to running in my rebuilt engine an im suffering from bad mayo in my expansion tank. Had a sniffer test done for exhaust gases in coolant an didnt change colour at all.Car is showing no signs of poor or rough running. She idles and drives really nice, heats up nicely, never overheats and sits half way on the gauge all the time when crusing. The oil has been changed twice and both times perfectly water free. No smoke from exhaust and heaters work fine. Drained coolant today and all the top hoses have oil in them an when flushing could see oil sitting on top of the water in bucket.
It hasnt use hardly any oil only some from a small leak from the turbo return hose.
Im at a loss as to what could be the cause as car runs perfectly apart from the oil in the water. I dont know where to look next as i cant keep buying parts that "might" fix it. Im running a nissa?? copper rad and im thinking crack between oil cooler and rad core? But cant understand why no water or mayo in oil.
Your help guys would be very much appreciated.