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2013 Mini Cooper S Hatchback Auto trans 78,xxx miles. Replaced engine with claimed 14,000 miles.
After getting the engine replaced I test started to car and let it idle. I hear one alarming squeak and saw a large puff of smoke from the exhaust and shut the car off. I went problem searching and found milkshake of mixed oil/coolant on cyl 4 plug. I drained the oil and it was FULL of coolant. I did an oil change to to get some decent oil in the car. I then pulled all the plugs and and varying amounts of liquid in the cylinders. 1 & 2 were dry, 3 was damp, and 4 was wet. I assume they thin oil/coolant mix in the massively overfilled crankcase, moved passed the rings to get into those combustion chambers. I cranked with the plugs out and fresh oil the bottom to clear the cylinders. Then applied vacuum while cranking to further try to clear them. When I was happy that the cylinders were cleared I performed a compression test and had good compression across all 4 cylinders. At this time I pinched off the turbo coolant lines to eliminate it as an oil/coolant contamination point and filled the car with coolant. I didn't even try to crank it. I just pulled the oil drain plug and sure enough the pan was again full of coolant.
So now to my question. Other than the oil cooler/heat exchanger, should I be looking or any other source of coolant getting into the oil? Is there any other test I should run? The coolant gets into the oil massively and without the aid of the water pump or combustion pressure. Is there any way to eliminate the oil filter housing (internal crack), or cracks inside the head or block? Has anyone seen a failed heat exchanger pass tons of coolant into the oil?
For some reference, put in 5 liters of coolant and got that much out through the oil pan and it all ended up there almost as fast as I filled the coolant system. It is so bad and fast I was wondering if I could have some how hooked up a coolant pipe where an oil pipe should go (like around the turbo lines/aux water pump, filter housing) but I did some sanity checks and because of different connection types and sizes this doesn't seem possible and also everything looks right. I am just racking my brain. I am hoping it is just the heat exhanger but the cross over/leak just seems so damn fast.
Well it was the freeze plug. So so many thanks for this feedback. I could have seen chasing this for literal months. I don't know if I am happy it was something simple or pissed that this is even an issue.
I think I would prefer to tap and plug it with a threaded plug and RTV. Any reasons this is a bad idea? Anyone know the size this is best tapped to?
One down side to tapping and using NPT thread is it is no longer a freeze plug, it is a plug. If you are in a cold weather climate this could be an issue.
Well I, and the car, do live in a cold climate but I have never frozen my coolant or popped a freeze plug during the winter on any vehicle or engine. If this plug were to come out again I 100% guarantee the engine would get smoked because it will be back in the hands of my sister-in-law and there is zero chance she would do anything before damaging the engine.
Since this plug coming out does not seem to be a one off issue, I will sleep better knowing it will not come out again and can deal with the fact it isn't freeze protection anymore.
