Had a weird air bubble in the cooling system today. No issues on a trip fri-sat, it got hot (235-240) after a trip across town-shutdown-restart. cooled back to 190-200 per usual as soon as the fan ramped up. Pushed a ton of coolant into the overflow. Did a combustion gas test and it was clean. Water came out the neck as soon as the thermostat opened. I capped it and it drew a couple quarts back from overflow as it cooled. It’s never ever done anything like that. Very strange hiccough.
Threw AC gauges on it since they were out and pressure differential is high, so it’s got some extra restriction somewhere. It was all 100% new parts 4ish years ago. Annoying. It was only keeping up when on recirc at 95F. And either it doesn’t have a high pressure limit switch or that switch is bad, since with whatever cooling fan issue the truck has it’ll blow out the relief if I run ac while sitting still when it’s hot. Truck got a new fan clutch 2-3yr ago as first effort to repair this, which means it’s either wiring or ECU. Will redouble my research efforts to hot wire the stupid viscous fan heater.
Sarah’s Malibu held vacuum, so I charged it. Was flat empty. See how long that lasts. Got very close to in-spec pressures, at least something on that car (and something today) cooperated.