I got your request, but I am not sure how much new information I can add to what has already been posted. To assist you in your research, I have provided a short course in the issue. In answer to your question, BMWs do not regularly experience hyraulic lock. (As an aside, call it hydraulic lock instead of hydrolock, which is slang. You mention that you are dealing with suits, so it will help. Hydrolock is like calling a transmission a tranny, or a differential a diffy)

The oil separator issue has been around for some years on BMW engines. BMW has made several design modifications to reduce the likelihood of problems, but IMO it can still happen even with the modifications. The mods consist of insulated or heated drain lines.

Short trips are bad for engines, and even more so in very cold weather. The moisture (condensation) never gets boiled off from the engine oil, and eventually makes a milky-white paste that can been seen inside the oil filler cap. The real solution is to ensure that the engine gets hot enough, if not every trip, then at regular intervals. That burns off the water, and the oil is fine. Oil doesn't freeze, only the water does.

The BMW oil separator can get clogged by this paste if it builds up, then the drain line freezes up, and the engine crankcase is then essentially pressurized instead of vented. The usual result is that oil is pushed out of gaskets and other points, causing smoking when the oil hits the exhaust manifold. The usual failure point is the valve cover gasket.

In some cases, oil or condensation can drip into the intake manifold. Any liquid that enters the cylinders can potentially cause a hydraulic lock. It takes a fair amount of liquid to do that, and it isn't by any means automatic that a hydraulic lock will happen even if liquid gets in the cylinders. It can cause a bent connecting rod. Again, that isn't automatic. A hydraulically locked engine can sometimes be repaired by removing the spark plugs, evacuating the liquid, inspecting the cylinders with a boroscope, and if all looks OK, putting it back together. If it has been determined that the connecting rods are bent, then you are looking at a major engine repair. The price you mention is conceivable, but we have no way of knowing what they are planning to do for that price.

BMW may assume some responsibility, but they are likely not required to if you are out of warranty. You could ask your dealer if they are assuming any responsibility given the history of failures. It would likely be a cost-sharing arrangement for the repair, at best. They will not pay for a repair done at other than the dealership. Any aftermarket warranty is not so much a warranty as an insurance policy. As with all insurance policies, the insurer will work to maximize sales revenue while minimizing payouts. If they have an exclusion covering weather, it seems to me that they will try to play that card. I do think that that clause should be applied to floods (as an example) rather than cold weather when you expect your vehicle to operate. At the ambient temperatures you are likely operating in, the vehicle battery starts the engine, the antifreeze is protecting the coolant from freezing, and other vehicle systems function. Suggesting that the cold, by itself, caused the problem is illogical IMO.

In summary, the oil separator problem is well known, but it by no means happens to all BMW vehicles. I had lots of trips in very cold weather in my '03 3.0, and never had a problem. Short trips makes the problem more likely. A problem with the oil separator usually results in the engine forcing oil out of the engine. It can result in the oil or condensation being forced into the intake manifold. That can potentially cause a hydraulic lock. That can result in major engine repairs. It is just that all the stars have to line up (the wrong way, in this case) for the oil separator to cause a hydraulic lock. Blaming it solely on the weather doesn't seem reasonable, but as I said above, that is how insurance companies work.

Good luck, and let us know how it turns out.

Jeff

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2007 X3 3.0si, 6 MT, Premium, White

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