[airlia101]

As the title hints, last night's drive home ended poorly LOL

Three questions, for you who know better than I:

How durable are these 2.3Lengines against overheating damage?

What temperature would the sensor need to reach to start throwing the P0117 CEL error? (That was my hint something went wrong)

I just finished an alternator/serpentine belt/tensioner replacement. What're the chances I did something to cause this? (Isn't water pump on that belt?)

Thanks, and happy new year to you!

 

[DrFeelGood]

Bummer. It is possible the belt was not put on correctly and as a result it is slipping on the cooling pump. This would be especially true if this is the first drive since the service and all was well before. As for the ECT low it is possible that the sensor was dislodged during service inadvertently. As for the overheating, I would top it off and see if it runs. If the overheat was very bad with cylinder pinging and audible clatter I would probably replace the oil as well as topping coolant before giving it a go.
I would inspect it carefully and verify with your hands if necessary that the belt is correctly seated on every pulley. I believe the 4cyl also has an alignment point to help verify.
Best of fortune.

@airlia101

 

[airlia101]

@DrFeelGood thanks for the reply I rented a car for the busy workday yesterday, and am only now digging into the Mazda.

No coolant left in overflow, and none visible in the radiator, so after I have it jacked up and check the main hoses for damage, I'll fill with tapwater and if none leaks out, run for a few minutes. That'll let me get a good look at the tensioner position indicator, too

I did not hear any tapping or clatter -- though, highway speed made it harder -- so I am hoping minimal mech damage. I was already due for an oil change, so I'll plan that this weekend too.
It did start and run generally normal for 30 seconds while I backed it into position to jack up... here goes the rest.

 

[airlia101]

Well, that was an easy first find: burst upper hose. Here's hoping that is the cause, not just a symptom.
Figure I'll just buy the full set of 3; now, to just track them down on this island...

 

[airlia101]

Update: Replaced both 1.25" hoses that connect to the radiator. The one going from the joint pipe up to the thermostat wasn't in stock anywhere, so I'll order that online and replace later... probably.

I'm concerned now that I might have a more serious internal issue... or else, these engines are just really tricky to bleed the air out of. Basically, I replaced hoses, flushed, and refilled, and one test drive seemed okay.... but the second again overheated (or, started to). Midday, sunny, A/C on, stoplight - gauge climbed up to 3/4, and as I turned into the driveway, hit about 7/8 up to Red. OBD scanner reported 114`C at "middle", 116`C at "3/4", and 117`C at "7/8".

Do those sound numbers match what y'all would expect with those temp gauge positions?
I get into the "middle" temp gauge position around 70`C or so. I know they're not linear gauges, but only ever remembered reaching ~110`C or so, maybe 113`C, before the overheat.

According to the service manual, the cooling system capacity is 7.4 quarts.
I drained out about 0.5 quarts of fluid from the radiator, replaced hoses, and refilled the radiator with 3.5qt of water.
Ran up to temp, cooled, and drained 2.0 qts.
Added 4.0 qts, ran, drained 5.0 qts.
Mixed up the coolant+water, added 4.5 qts. Now, at least 5 qts in system. Radiator seems full. Added about 0.25qt to overflow reservoir.
Ran up to temp, cooled overnight. Added ~1.5 qts this morning. Radiator seemed full again. Overflow low, added another 0.5qt
Ran out for groceries. Temps behaved on the way (max reading 115, for about 10 seconds, usually 113-114)
Returning from groceries, gauge started climbing at a red light. Turned off A/C, started moving again, but still a slow climb. OBD temps at 116-117, pretty steady.
Cooled car off, checked later, added about 1/2 cup (0.125 qt, if you're counting) to top off the radiator.

So, now I have put in a net 6.5 quarts via radiator, plus .875qts via the overflow. If I'd managed to completely drain the system between the broken hose and the initial drain, that's about what I would expect... is that likely?
Does this sound like "expected" behavior for a bit of an air pocket still the system?

I guess I'm going to go and give it one more test drive tonight, before I drive up a hill to work tomorrow 🙃

Coming from Subarus, headgasket failures from or because of overheating are always on my mind...

 

[DrFeelGood]

@airlia101 you are right to be concerned about cooling. I do not know about the 4cyl and bleeding but the v6 is a bear to bleed. I have never been successful using the factor method for air bleeding in the 6s. I have to disconnect the reservoir tank hose and fill through there while massaging all the radiator hoses vigorously. I have had an instance where the heads started overheating as a result of no coolant circulation, but the gauge read low (I am assuming there was no coolant in contact with the sender to report a reading). The sound of valve clatter told me something was critically wrong.

Make sure the heater is open when filling.

Good luck, if I think about anything else I will post.