euygur

3.2 TLS Radiator coolant level is getting low, extension bottle level getting high. is that Radiator cap problem?

Changed cap but, still problem is same. (Cap was not OEM)

blackhorse21

On my case, it is the tube between the radiator cap and reservoir bottle. The tube got old and loose tension at both ends but not that much to cause a significant leak. So when the coolant is hot, the cap will function and export coolant to the reservoir bottle. That can be done easily since the cap is higher than the bottle. But when the engine cool down and need to suck coolant back, any leak between the tube and connector will allow air to be sucked in first. Since air is way lighter than coolant. So for every cycle, the engine gets hot, put coolant into bottle, cool down and suck air back.
What I did is adding a tube clamp (the type that can be tighten by screw) on the end next to radiator, and two zip ties on the end next to bottle. Zip ties does not work on the radiator end since it will be warmed up and also lose tension.
Hope this help!