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Discussion Starter · #1 ·
So, my xb tried to overheat on me last night. I have an ultragauge that I monitor the engine temps with and it has always stayed at 185 no matter what the conditions were. Last night I was driving home in some stop and go traffic and the temp climed to over 200. I was almost home so I just turned on the heater, the temp dropped and I parked it. I came out this morning and did a visual inspection and could not find any leaks and the radiator was full. I started the car and let it idle until the temps started to climb into the 200's again. I didn't think my fan was kicking on, so I turned on the a/c and the fan kicked on and the temps dropped. I decided to drive some more. As long as I'm moving the temps stay relatively fine. At a stop, or under heavy load like going up hill the temps will start to climb. All of this is based off of what my UG is telling me, I haven't triggered the actual temp light yet and have no CEL or trouble codes. When exactly is the fan supposed to be kicking on and what should I check if it isn't? It doesn't seem like that's my only problem though since the temps will also start to climb when I'm moving, but under load. I just turned 94,000 so I'm sure I'm probably due for a water pump as well. Any other ideas or suggestions? Thanks.
 

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Pishtaco
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The low speed fan goes on when the AC is turned on and temperature is at least normal.

The high speed fan goes on when coolant temperature tops 204, or when temperature tops 186 with AC on.

I'm not the lowest of the low, but I am the slowest of the slow (49.6 mpg over 38k miles in Scion xB)
 

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Discussion Starter · #3 ·
So as long as the a/c is off and the temp stays below 204 the fan shouldn't kick on at all?

---------- Post added 03-17-2013 at 04:33 PM ----------

So it seems like the fan isn't my problem. Anybody got any ideas as to what this could be? What kind of temps should I be expecting for normal driving conditions? Am I just being paranoid? Thanks.
 

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Pishtaco
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So as long as the a/c is off and the temp stays below 204 the fan shouldn't kick on at all?
Correct.
So it seems like the fan isn't my problem. Anybody got any ideas as to what this could be? What kind of temps should I be expecting for normal driving conditions? Am I just being paranoid? Thanks.
I don't see any problem until temps climb over 204 and stay there. Normally the fan kicks in >204, and the cooling system brings temps down. The only time I would worry is when the fan fails to bring the temps down.

I rigged up a dash light from fan relay 2 (the high speed fan relay), so I get a visual warning whenever the high speed fan turns on.
 

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Discussion Starter · #5 ·
I've been monitoring the temps much more closely since the other day. Depending on how I'm driving, like coasting down a hill instead of pulling up it, the temp will actually drop below levels I was used to seeing as well. All in all it's been staying within normal operating temps although fluctuating more than I'm used to seeing. I guess I just kind of freaked when I noticed it doing something out of the ordinary, but I suppose there's no harm done yet. My biggest concern was that this was a sign of some impending doom. Guess I'll just be keeping my eye on it. Thanks.
 

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Towster ['__'`,-,
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When coasting, the engine can cool to as low as 177.

When going up inclines, you can easily hit 200.

When I was towing two jet skis in 110 degree weather in the desert, my UG hit 218 degrees at one point, but the red temp light never went on.

Dont worry about overheating until you see the red temp light go off. And, if you are really hot, then the light will blink.
 

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Super Moderator
2006 Scion xB Automatic
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Dont worry about overheating until you see the red temp light go off. And, if you are really hot, then the light will blink.
Does anyone happen to know at what temperature the red temp light turns on? I'd like to set my new OBD stats screen to do an audio alarm when that happens, but don't really want to try and get to that point just to set up the alarm, ya know? :D
 

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xB Leaving Pit Soon
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Not positive, however, memory serves the Gen1 high temperature lamp illuminates at 205 degrees Fahrenheit. Can you monitor the OBD readouts for a while and after several days set your alarm at a preferred level?
 

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2006 Scion xB Automatic
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Not positive, however, memory serves the Gen1 high temperature lamp illuminates at 205 degrees Fahrenheit. Can you monitor the OBD readouts for a while and after several days set your alarm at a preferred level?
I drove it to grab dinner last night and it got up to 227 without the red light illuminating. I had my new OBD visualizer set to start beeping at 220, which it did. From the manufacturer, the OBD device's ECT alarm was set at 230, so I may set it back to that. I ultimately want to set the beeping to start 2 degrees before the red light comes on.

I've also discovered that 140 is when the blue light turns off.

I tested the OBD thingy on my Honda Passport the day it arrived, and it never got above 190, even with our ridiculous current temps here and the a/c on full blast. I was impressed. So there's obviously something wrong with my xB, I may just replace the thermostat to see if it's a quick easy miracle fix like that. 🤞 If that doesn't do the trick, my troubleshooting skills are done. (It's not dripping coolant, the oil and transmission fluid are not milky/milkshakey... The radiator is not blocked or has bent fins...?) But it's losing coolant somehow.
 

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xB Leaving Pit Soon
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Great research and data on the temperature setting!

Pressure test the radiator to ensure there is not a leak in the system.

Pull the xB's spark plugs and see if any of them are a lot cleaner than the others. That is an indicator of an infinitesimal leak in the head gasket. Such a minute leak permits burning the coolant and is not enough to cause a plug to foul or to permit coolant to mix with the engine oil. Unless the leak increases, it will not be visible in the tailpipe exhaust. I hope this is not the issue and it turns out to be something simpler.
 
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