How simple is it to put a clamp on that hose we talked about? Easier than doing a thermostat. Your call.
2000 Yukon-Long warm up time - partial heater core restriction possibly?
- Thread starter UmmScott
- Start date
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rockola1971
Full Access Member
I wouldnt care too much about how accurate the thermal gun is. Lets say its 5 degrees low. The reading will be 5 deg low on both readings you took. Taking temp readings WHILE THE HEAT is on you SHOULD see a substantial heat drop on the outlet. The heat went into your cabin. With the HEAT AND BLOWER TURNED OFF you shouldnt see much of a temp drop between inlet and outlet of heater core. If you do then your core is plugging up.
Sure sound like your thermostat isnt regulating very well. Id replace it.
Sure sound like your thermostat isnt regulating very well. Id replace it.
Splorg
Full Access Member
Sorry, I only glanced through the messages, someone may have asked already - thermostats are cheap. Replace it. Stuck open thermostat would act like this.
Is your fan clutch working? I don't have a ton of experience with mechanical fans, but I'm assuming if it was running full tilt it could cause this as well. Most likely it's a combination of a stuck/improper thermostat and your fan clutch spinning the fan at max all the time.
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Is your fan clutch working? I don't have a ton of experience with mechanical fans, but I'm assuming if it was running full tilt it could cause this as well. Most likely it's a combination of a stuck/improper thermostat and your fan clutch spinning the fan at max all the time.
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Just following up with you guys.
I bought a GM original stat for a much lower price online. Going to replace it but i wanna share what a local shop said while i had them test my ABS system. (Separate issue).
They think my heater core is restricted. They said i have large temperature drops across the hoses going to the heater core with the fan on high.
My thoughts (and what another guy said on here).. if you have the fan on high and its 0F outside youre gonna have a temp drop no matter what. Blowing cold 0F air across a 170 to 180F heater core im gonna bet there will be at least a 30F drop in outlet temp there.
Today, it was 0F out. I let it idle for almost 10 mins and drove 5 miles to the shop. Had basically no heat the entire time and temp gauge barely moved from the far left.
In short... I'm pretty sure I'm/We are correct. Thermostat is bad. Did some digging in the trucks records and a 379-187 motorad stat is in the truck now from last year.
They only had the truck for an hour. Just had them do an oil change and pull the codes. They said they "would need more time to check it out fully but think its heater core related"
What do u guys think?
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I bought a GM original stat for a much lower price online. Going to replace it but i wanna share what a local shop said while i had them test my ABS system. (Separate issue).
They think my heater core is restricted. They said i have large temperature drops across the hoses going to the heater core with the fan on high.
My thoughts (and what another guy said on here).. if you have the fan on high and its 0F outside youre gonna have a temp drop no matter what. Blowing cold 0F air across a 170 to 180F heater core im gonna bet there will be at least a 30F drop in outlet temp there.
Today, it was 0F out. I let it idle for almost 10 mins and drove 5 miles to the shop. Had basically no heat the entire time and temp gauge barely moved from the far left.
In short... I'm pretty sure I'm/We are correct. Thermostat is bad. Did some digging in the trucks records and a 379-187 motorad stat is in the truck now from last year.
They only had the truck for an hour. Just had them do an oil change and pull the codes. They said they "would need more time to check it out fully but think its heater core related"
What do u guys think?
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I think you are closer with the thermostat than they are. Yes a temp drop is expected when running the fan. If the heat and fan is not on the hoses should be close to same temp. Should be hard to hold on to with a bare hand. A bad/clogged heater core will never effect the temp gauge. The basics say start with the thermo from here and check after. You may still need heater core replacement but at least get the heart of the system to work correctly with a quality part.
Fully agree.
Ill get it changed as soon as i can. Its Cold here!! Lol
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Update.
Got thermostat changed. Heres a pic of them the new ACDelco one is on the bottom and the motorad one that was in the truck is on the top.
Anyhow...put it all back together, filled the coolant back up, and test drove it.
While it was not as cold today, only 27F instead of 0F lol, Im pretty sure I have a big difference. I have lukewarm to mild heat right before the temp gauge even starts moving past 160F.
Before with the old stat i had practically no heat even when the temp gauge started moving.
We will see. Ill let it cool completely down and see how it does on a really cold day.
[emoji106][emoji106][emoji16][emoji16]
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Got thermostat changed. Heres a pic of them the new ACDelco one is on the bottom and the motorad one that was in the truck is on the top.
Anyhow...put it all back together, filled the coolant back up, and test drove it.
While it was not as cold today, only 27F instead of 0F lol, Im pretty sure I have a big difference. I have lukewarm to mild heat right before the temp gauge even starts moving past 160F.
Before with the old stat i had practically no heat even when the temp gauge started moving.
We will see. Ill let it cool completely down and see how it does on a really cold day.
[emoji106][emoji106][emoji16][emoji16]
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Splorg
Full Access Member
Glad to hear you think you've gotten it licked!
Not sure what the other guys experience is, but my Yukon can sit and idle for quite a long time and not generate heat. Since I replaced the water pump and thermostat, though, if I start driving it it only takes a few minutes to have some sort of heat. Idling it doesn't seem to help at all, still.
I'll cross my fingers for you that it completely resolves your problem! Now that mother nature has decided that winter might not be a bad idea you're going to need it!
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Not sure what the other guys experience is, but my Yukon can sit and idle for quite a long time and not generate heat. Since I replaced the water pump and thermostat, though, if I start driving it it only takes a few minutes to have some sort of heat. Idling it doesn't seem to help at all, still.
I'll cross my fingers for you that it completely resolves your problem! Now that mother nature has decided that winter might not be a bad idea you're going to need it!
Sent from my SM-S727VL using Tapatalk
I see the new thermo has the vent hole in the thermostat. Did the old one?
JonnyTahoe
Full Access Member
Unless its really cold you should be getting heat just starting the engine and letting it run. The computer does all the rest (as we all know). It's completely normal for the engine to run a bit rough for a minute or so especially if it's really cold but it should stay running on it's own. I actually wish it would run at the start-up rpm longer before slowly coming down to the normal idle.
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