I have a 2003 MX Z 600 and am somehow getting moisture in the chaincase, making the lube in there real milky. I canâ€™t find where the water or moisture would be getting in, as there are no visible external leaks around the chaincase or any oil leaking on the ground. Have you heard of any problems like this from the field?
Usually moisture in the chaincase is coming in through the vent, and on your sled the case is vented through the dipstick. Normally it is caused by running in water (skipping, slush, excessive drift busting) or storing the sled is a warm, moist environment. If the case is hot and enters an environment where there is water, it pulls some in as it cools, but this isnâ€™t really common, or anything. I suppose it could be pulled in past the seal on the drive shaft, but more likely is through the vent. Make sure youâ€™re using a good synthetic lube, but I donâ€™t have a clear cut answer for you. This is one of the reasons chaincase lube should be inspected (for this condition) and drained and refilled at least every year. The water will lead to corrosion and problems down the road if left unchecked. Not to mention what happens if the chain tension is ignored!