Coolant tank cap popped off and no coolant left

[Docboy]

Over the weekend, I popped my hood off the LX570 (2009, 106k miles). I noticed that the plastic snap on lid to the clear plastic reservoir was not on the reservoir, so there was a gap between the clear reservoir and the lid. I also saw that there was literally NO coolant in the reservoir.

I'm not sure how long this cap has been off and dangling from the reservoir, and I didn't see any pink residue around or below the tank. The radiator is still holding up and no visible cracks.

Can anyone confirm that coolant can evaporate if the lid to the reservoir is not capped on tightly?

 

[turbo8]

Once your vehicle is cool, open the radiator cap, is the radiator full?

 

[Docboy]

Once your vehicle is cool, open the radiator cap, is the radiator full?

Yes, I opened the radiator cap and it was full of coolant. Vehicle sat overnight in the garage fyi.

 

[OregonLC]

Can anyone confirm that coolant can evaporate if the lid to the reservoir is not capped on tightly?

The overflow from the reservoir is open to atmosphere so if evaporative loss was an issue it would be happening all the time, albeit with a slower rate with the smaller orifice.

As long as your radiator is full of coolant, you don't see any visible leaks, don't smell coolant, and didn't have any temp excursions then I wouldn't worry too much. Fill up the res to the max line and monitor over the next several weeks with the cap back on. If you continue to have a loss rate then it's worth investigating further.

 

[Docboy]

The overflow from the reservoir is open to atmosphere so if evaporative loss was an issue it would be happening all the time, albeit with a slower rate with the smaller orifice.

As long as your radiator is full of coolant, you don't see any visible leaks, don't smell coolant, and didn't have any temp excursions then I wouldn't worry too much. Fill up the res to the max line and monitor over the next several weeks with the cap back on. If you continue to have a loss rate then it's worth investigating further.

Thanks, will do!