It could be the sensor, thermostat, or gauge.
Tonyrodz's Tahoe Build Thread
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Tonyrodz
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Def not the gauge. I took it for a ride last weekend, then checked for pressure in the system--wasn't any, and the gauge was a little past 160. I've never had a problem with the cluster before, and it was rebuilt. I know that doesn't mean anything tho.
How are you checking for pressure?
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Tonyrodz
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Just by hand, squeezing the upper radio hose, and the inlet/outlet hoses for the heater core. You can also see the coolant feeding(circulating) into the overflow bottle when it's running. When the system is pressurized you don't see it doing that.
pwtr02ss
Full Access Member
Maybe you can check the ohms or something? IDK, Ive never had to check one lol
Shotgun method.
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Tonyrodz
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Shotgun method.
pwtr02ss
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Tonyrodz
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Thx for the video. Seems easy enough.
pwtr02ss
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For the record, I did not watch the video. It was just the first one that popped up in google
iamdub
Full Access Member
I thought pressure in the system, in addition to raising the boiling point of the coolant, ensured there was no room for air pockets to form. So, wouldn't lower pressure allow warmer coolant temps?
Also, if the actual temp is fine but the sensor was reading low, is it possible the PCM would adjust fuel and spark erroneously for cooler temps, leading to unnecessarily longer warm-up times and rich exhaust?
Also, if the actual temp is fine but the sensor was reading low, is it possible the PCM would adjust fuel and spark erroneously for cooler temps, leading to unnecessarily longer warm-up times and rich exhaust?
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Tonyrodz
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Makes sense.
Have you compared the Tech 2 coolant temp reading with what's on the gauge?
Is the surge tank cap good, does it hold pressure?
Is the surge tank cap good, does it hold pressure?
The ECT is a two-wire thermistor, so you can measure the resistance between the two pins. Here's what I believe to be the correct chart for NBS ECTs:
Also this video might help:
EDIT: you can also, on a cold engine, compare the IAT temp with the ECT temp; they should be very close to each other, say 5°F or so.
Also this video might help:
EDIT: you can also, on a cold engine, compare the IAT temp with the ECT temp; they should be very close to each other, say 5°F or so.
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Tonyrodz
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I did replace the coolant cap recently, around the same time as I was checking the plugs. The truck doesn't get driven much anymore, so it wasn't noticed right away. I'm getting a replacement for the new cap. Hopefully it's just a defective cap. Thx @Fless for helping again!
To add, if you test the resistance and compare it to the chart temps, be sure the sender is in liquid, and know that liquid's temp. Testing it in air may not be accurate.
Also wouldn't hurt to toss a scanner on it to compare the IAT and ECT temps. Quick read!
One other random thought -- think about renting the free cooling system pressure test kit from your local auto parts store, and manually pressurize the system. The kit might even have a way to test the surge tank cap.
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Tonyrodz
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Hopefully I can mess with it this weekend. We're supposedly getting a "Bomb Cyclone" snow storm coming. But the range will be anywhere from a dusting to 18 inches. I guess we're gonna see who's right later on tonight.
I was just coming over here to ask you about that. I saw it on the news. That looks like a helluva storm, lots of snow and super cold too, single digits, plus wind. Hoping for the best for ya Tony.
