There is something strange going on with my 2018 XTS and maybe someone can help explain it. Often times my car will sit for a week at a time. After a week, if I look under the car, the floor is completely dry. Then, when I start it and back out, all of a sudden there is a puddle of water on the floor. I have examined it closely, and confirmed that it is clear water, and not engine coolant. The puddle is located below the area where I believe the evaporator drain is located. I am aware that it is normal to have condensate drain from that tube when the A/C is operating, but after sitting for a week, and there is no water on the floor, one would think that all of the water has been drained from the evaporator several days ago. So why, all of a sudden do I get water on the floor the moment I start it up? Could it be that some of the water was trapped in the evaporator enclosure and unable to drain out until I started the car, and then it somehow gets blown out? That's my only theory, but would be interested in other opinions. Fortunately it is not causing a real problem of any kind. I did check my coolant level and it is holding steady.
Water Under Car
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It has me stumped. I'll keep looking for clues and giving it more thought. If and when I ever have an occasion to take it to the Cadillac dealer, I'll ask the service people what they think of it.
Wow, that's pretty extreme all right. But no, that is not the cause of my issue because in my case, the water is coming from the center of the car, not the rear. Thanks for the suggestion.
It is just water sitting in the exhaust or evaporator core drain that’s getting blown out. The evap core drain tubes I’ve seen have “lips” on them (for lack of a better description). Those lips kind of stick together or seal together and can hold some water.
Looks like the muffler weep holes in the CT6 are clogged.
I drove my '18 today, it had been setting 2 days. I actually let it run for a minute before backing out, no water under car. It has been cooler here in KY.
I think Cutlass may have something about the lips on the evaporator drain tube holding up some water until it gets blown out at startup. I just can't see it being a serious problem. Soon it will be cold enough for the heater to totally dry out the evaporator enclosure, so I don't expect to see any water all winter long.
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