Need heat!

[DallasTahoe]

98 Yukon, heat blows hot when driving but not when I’m at a light or idling, just kind of warm, it’s 26 degrees in Dallas right now, so kinda like to be warm lol. It’s full of antifreeze and the fan does blow like it should. I don’t want to take any antifreeze out, anything I can do?


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[OR VietVet]

Basics first. Is the coolant full? How old is the thermostat? How old is the water pump? I would be worried that there is impeller problems at the back of water pump. Check for good flow thru the heater core by checking the heat of both core hoses and see if the temps are close to the same. Possibly a heater control valve having a vacuum problem at idle.

https://www.rockauto.com/en/moreinfo.php?pk=84579&cc=1305076&jsn=2238

https://www.rockauto.com/en/moreinfo.php?pk=679484&cc=1305076&jsn=2249

https://www.rockauto.com/en/moreinfo.php?pk=1021536&cc=1305076&jsn=2272

 

[DallasTahoe]

Everything is pretty much new, I think I made my cooling system too efficient, runs really cool in the summer with the ac on in 100+ heat


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[OR VietVet]

What degree thermostat is in it and does it have the little weep hole in the thermostat plate for bypass?

 

[OR VietVet]

Did you do the radiator too? New radiator?

 

[Fless]

What temp does a scan tool say the coolant temp sensor is reporting when it's warmed up?

 

[DallasTahoe]

What degree thermostat is in it and does it have the little weep hole in the thermostat plate for bypass?

190


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[DallasTahoe]

Did you do the radiator too? New radiator?

Yep


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[DallasTahoe]

What degree thermostat is in it and does it have the little weep hole in the thermostat plate for bypass?

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[OR VietVet]

Your, too efficient, analogy may be spot on. Try using a piece of cardboard and put in front of the radiator on the grill and tie it off some how. Then drive it and watch the engine temp to make sure it does not get too high. See if is warmer at stops. Is the fan clutch new as well?

 

[OR VietVet]

190


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Ok, answer the other question. Does it have the weep hole in the thermostat plate?

 

[DallasTahoe]

Ok, answer the other question. Does it have the weep hole in the thermostat plate?

Yes it does


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[DallasTahoe]

Your, too efficient, analogy may be spot on. Try using a piece of cardboard and put in front of the radiator on the grill and tie it off some how. Then drive it and watch the engine temp to make sure it does not get too high. See if is warmer at stops. Is the fan clutch new as well?

That’s what I’m thinking, I’m running 05 Chevy fans, they’re adjustable so maybe I should just turn them up so they’ll kick on at a higher temp duh, don’t know why I didn’t think of that til just now [emoji2375]


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[OR VietVet]

Yea, it would have helped, in the very beginning, to share all the new parts and the upgrade to electric fans, to help with the, "figure the ****** out", problem.

At speed on the highway, and more flow from the water pump, you really don't need a fan at all, but with a new rad and thermo and then fans on at slow speed and idle, it may be blowing all that heat out at the radiator before it gets to your heater core.

 

[DallasTahoe]

Yea, it would have helped, in the very beginning, to share all the new parts and the upgrade to electric fans, to help with the, "figure the ****** out", problem.

At speed on the highway, and more flow from the water pump, you really don't need a fan at all, but with a new rad and thermo and then fans on at slow speed and idle, it may be blowing all that heat out at the radiator before it gets to your heater core.

Sorry, the fans have been on for so long it’s normal for me, and kinda hard to list every single little thing I’ve changed or upgraded. Also I’ve learned if you give too much info right off the bat, then it tends to help less, because if there is something I missed during the course of me trying to figure it out first, you guys bring a whole new perspective. Thanks for the help though, completely forgot about the fan adjustment


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[Fless]

I may be way off base here, but I'm wondering if the OE radiators have the restriction in the line to the surge tank, like the NBS trucks do. If they do, and the radiator was changed, maybe the new radiator doesn't have that restriction in the line? That can keep the engine temp from coming up to spec.

 

[OR VietVet]

I may be way off base here, but I'm wondering if the OE radiators have the restriction in the line to the surge tank, like the NBS trucks do. If they do, and the radiator was changed, maybe the new radiator doesn't have that restriction in the line? That can keep the engine temp from coming up to spec.

I thought about the same thing when I was asking about the radiator being new or not. A quick way to check is to put a small hose clamp on the surge tank line and then tighten a little to restrict flow but don't shut off flow completely. See if that does the trick. Thanks @Fless