Low Coolant... How To Tell If Top Of Coolant Tank Has Been Changed?

[90LS400Lexus]

My cars coolant level is lower and lower when the engine is cold. I think its the cap, because I dont see any leaks anywhere and the pump only has about 20K on it.

I called the local Lexus dealer and he said that some of those had been changed because of a problem or something and wanted to know if I knew if my car had the changed top on the tank. I have no clue. Then he said that one cap was all that was available and if it wasnt changed, I would have to get all of that replaced with the sensor, etc. He has got to be joking right? He said if it had then the cap only was $19.

I dont want to run it low on coolant, but dont want to put in $25 coolant (pink) to go back out either.

If the car is not losing visible coolant, where could it be going? Its a very low loss, because I have put 30K on it and never had to add any, but its getting lower and lower in the tank.

[90LS400Lexus]

I am just going to top off with distilled water and go from there. Someone said it may have been a little low from the PS pump change or the fan bracket bearing change and some coolant was lost in the process.

[90LS400Lexus]

This morning coolant could not even be seen in the tank, but this evening, when the engine was hot it was only lightly below the "cold" line. I am not sure where its supposed to be when the engine is not. Full I guess.

Anyway, out of frustration (its been one of those evenings) I filled it as full as I could with distilled water. I have no idea whats going on, or if I am worrying prematurely. It was low somewhat even when I bought the car.... its just lower than before. Again, no visible leaks... water pump only has about 24K on it. So.... <_<

[90LS400Lexus]

OK... seems fine now... level is full and its good to -25°F, which is about 30° colder than we will ever see even in the harshest artic outbreaks. :)

I added this much water (jug was full)

this is the result...

everything should be good to go now....

tranny fluid still looks OK...

oil OK.. changed 1000 ago...

power steering fluid fresh... (and staying full now that the leak is gone)

timing belt/water pump have about 28K on them....

just needs to be detailed again...

took this 3 weeks ago...

Mom said they do want to buy it next month... selling it to them for $2400.... so I am trying to get it in a good of shape as possible. Valve cover gaskets and motor mounts will be their problem. I am going to have the throttle body cleaned this week though.

[killerFatty]

based on the dry residue left around the coolent resivior, I'd say it's leaking. Mine looked just like that and lost about a cup every two weeks depending on how much I drove. I got a new resivour off a parts car from a guy I know for $20 and it was suprising super easy to replace. Hasn't leaked a drop since. Just look for a used one in good condition and swap them out. Not a major job at all.