2018 GX 460 ~108K miles. Have not had issues with overheating.


I changed the coolant at 90K. And noticed a pink crust on the sides of the overflow bottle around where the cap snaps on. I cleaned, drove and the crust came back.

I then purchased a radiator cap from Lexus and replaced as I know these get weak.

Still, the issue persists. Should I replace the overflow line and black cap as well?

 

You might be adding too much coolant in the reservoir if so coolant will be pushed out until the level stabilizes. Are you certain the radiator isn't leaking or any other part of the cooling system?

 

I haven’t had to add any coolant since changing it 18K miles ago I’m fairly certain it isn’t leaking.

The level in the reservoir stays right below the F line when cold. When hot, it goes slightly above the F line, but I’ve never seen it reach the cap level firsthand.

 

At the F line when cold is too much coolant, but normally I see 2-3 inches of level change from cold to hot. FYI every car I work on with an overflow bottle does the same thing, when I initially fill with coolant I put more than normal in the reservoir since the system tends to draw in coolant as air gets purged. This always means coolant gets pushed out and I have the signature pink stain on the bottle.

 

Lubricate cap gasket with a little silicone grease and that will stop