Two questions about coolant change

Regarding #1: you’re probably fine. I let mine run about 1/2 hour, then gave up, fan never turned on.

regarding #2: you can buy hex socket sets, 3/8” or 1/2” drive; they’re a common mechanic tool.

 

It fits an ordinary hex key (commonly called "Allen") wrench of appropriate size.

 

The point of having the fans "come on twice" during the ICE system checkout is to have the engine run long enough that presumably the thermostat is opened and purged any air.

The fan comes on once- the engine is hot. The fan goes off- the temperature has gone down some (ie the cooling system is actually working). The fan comes on again- temperature control should be stabilized.

Early on in the process, I monitor ECT on my scantool, and as it goes up, I check for warm air from the heater.

For the inverter system, the only real concern is verifying good coolant circulation and purging any air. That's not directly tied to how long the ICE runs.

Posted via the PriusChat mobile app.

 

That's just one way to make sure the coolant is hot enough for the thermostat to open, allowing coolant to circulate through the radiator. That should help push any air pockets out. Same is true of waiting for fans to come on.

 

The key is to warm up the engine well enough that the thermostat fully opens, and then run it several minutes longer, while shaking and squeezing some hoses to dislodge more air.

Before the thermostat opens, there are parts of the system where coolant isn't circulating, so the last of the air isn't effectively removed until after it opens.

If the weather is cool, it can take quite a long time for the engine to warm up enough that the thermostat opens. It can feel like forever if you haven't got something to watch. If you have a scan tool showing the coolant temperature rising, and you know what temperature the thermostat opens, then at least you have something to watch and you have a better idea how long you will be waiting, and it doesn't just feel like forever.

 

Something you can put on a ratchet wrench will be more stable and with a longish handle much easier to break it loose, and less prone to round the hole.

torque spec in one of the attached:

 

I’ve seen oil change people put the oil pan screw back on and begin tightening while engine oil was still draining when there was a long line of cars waiting for oil change.