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Anyone knows what is this hole at the lower part of the coolant tank, at the corner where the cap is at? Is this the relief valve of the tank?
I have been tracing a coolant leak it seems to come from there. It’s a new tank (mechanics replaced it when he couldn’t find where a leak was coming from in pressure tests couple of months ago). I suspect the leak was coming from same location before the tank was replaced (location of coolant dripping down is the same)
Assuming it is the relief valve, what could cause coolant coming out from there? I’m def not overfilling it. And given tank is new, and that coolant likely also came out from there with the old tank, maybe the pressure in the system was too high or something? What can cause unusual pressure buildup in the cooling system? Don’t see coolant temp high in driving. Any thoughts appreciated!
hole in question at the bottom of the tank at this corner
I think you assumption is correct. It seems this hole goes up to the cap where if tight correctly (when it falls in place) connects to a whole in the cap (probably the cap has the pressure relief valve). The pressure usually comes from temperature and\or bad antifreeze... If you still loosing antifreeze from there I would suggest you to buy some cheep OBD2 Bluetooth reader and log the temperature. As far as I managed to find info anything over 100 Celsius is considered on the overheating side and maybe you should check antifreeze quality, radiator, water pump and valve...
It is also possible the valve on the pressure cap on the expansion tank to have gone bad (but if it's leaking antifreeze I don't think so)...
I myself also dealing with a similar problemnafyer changing the water pump(I have noticed temperatures up to 105 and loosing a lot of coolant with no obvous place)
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