The cooling system will only draw from the reservoir as the system cools causing a vacuum in the cooling system. The vacuum side of the pressure cap has to be in good shape. If there’s a system leak, it might draw air instead of coolant. With 200K miles on the clock, I remove the pressure cap to check coolant level weekly regardless of reservoir level. Too much to leave to chance.
I have no experience with a 2GR with bleed port but bleeding a 3MZ with a big funnel over the pressure cap fitting, excess coolant in the funnel and idling with both heater cores flowing until the thermostat opens works very well.
The coolant lines to the rear core are awkward to get hands on. Maybe easier without the spare. That should confirm whether coolant is flowing to the heater core.
Sixto
‘04 LE FWD 203K miles
I have no experience with a 2GR with bleed port but bleeding a 3MZ with a big funnel over the pressure cap fitting, excess coolant in the funnel and idling with both heater cores flowing until the thermostat opens works very well.
The coolant lines to the rear core are awkward to get hands on. Maybe easier without the spare. That should confirm whether coolant is flowing to the heater core.
Sixto
‘04 LE FWD 203K miles
