07 tahoe coolant temp issue

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iamdub

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Is it actually running hotter than it should? My point is that temp sensors go bad and can read incorrectly. The PCM won't know any different and will just react as programmed based on what the temp sensor is telling it.
 
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Erik Christenson

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The radiator was new and purchased from the dealership. When they checked it, supposedly there is no clog. But since it's all under warranty, I might just get it replaced again. They also supposedly checked it with a scan tool as well.

Camshaft was set straight up, yes. AC Delco anti freeze, 50/50 I believe.

I have a Kenwood deck that shows the gauges and everything checks out there.

The dash gauge used to sit right below the 210 mark, now when warmed up it reads dead on, hence why I think the fans kick on and stay on.

Fan does turn on at correct temperatures, but won't shut down unless I turn the car off and wait for it to cool down.

Also, just so everyone's on the same page. It's running a degree or two higher I think, just enough to keep the fans on, but the thermostat, which is replaced does its job correctly too. So, obviously the second fan doesn't turn on because it's not overheating.

Thanks guys for all your help so far btw!
 

kbuskill

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The radiator was new and purchased from the dealership. When they checked it, supposedly there is no clog. But since it's all under warranty, I might just get it replaced again. They also supposedly checked it with a scan tool as well.

Camshaft was set straight up, yes. AC Delco anti freeze, 50/50 I believe.

I have a Kenwood deck that shows the gauges and everything checks out there.

The dash gauge used to sit right below the 210 mark, now when warmed up it reads dead on, hence why I think the fans kick on and stay on.

Fan does turn on at correct temperatures, but won't shut down unless I turn the car off and wait for it to cool down.

Also, just so everyone's on the same page. It's running a degree or two higher I think, just enough to keep the fans on, but the thermostat, which is replaced does its job correctly too. So, obviously the second fan doesn't turn on because it's not overheating.

Thanks guys for all your help so far btw!

While I don't have the specs in front of me I do know that the ECM calls for the fans to be turned on at varying percentages (speeds) at varying temperatures (degrees).

To me it doesn't sound like there is a problem. One fan off, one fan running at probably less than 100% speed, truck not overheating, only running a degree or two higher on the gauge and the temperature sensor has been changed out which is probably the reason for the gauge reading higher by a couple degrees than what you are used to seeing.... what am I missing?

The fans for the most part aren't going to shut off completely after the truck is up to temperature while sitting and idling... it needs air flow to maintain a constant temperature IMO.
 

puckhead

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Does anyone have a chart or something that shows when each fan should be on or off?
 

puckhead

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I thought I read somewhere that these trucks will burp themselves when flushing/refilling the system and to just massage the hoses a bit. Is that not true?
 

kbuskill

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I thought I read somewhere that these trucks will burp themselves when flushing/refilling the system and to just massage the hoses a bit. Is that not true?

It's best to get the nose of the truck as high up in the air as possible. Ramps under front wheels or backing down a steep driveway or ditch.
 

swathdiver

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What Ken said is what I've always done. The shop manual said level ground and revving the motor at 2000-2500 rpms until it reaches temperature. I didn't know until reading this morning, that there are vents on the heads, on the inside, near the valley cover, front pair and a rear pair. My Pontiacs had little fittings to loosen to let air out as the motors were higher than the reservoir.
 

puckhead

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Just wanted to make sure. There's a ton of varying info out there. May as well clarify. After burping and running the engine like above the coolant level settled


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gpracer1

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Does anyone have a chart or something that shows when each fan should be on or off?

Oooops, forgot to respond to this thread.
EFI Live does not show that much data or options compared to my 99, but here is what it was stock.

Deg % Fan power
192 40
196 42
199 43
203 45
207 48
210 48
214 49
217 49
221 55
225 60%
228 80
232 90
235 95
239 97
243 97
246 97
250 97
 

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