Engine not reaching operating temperature

[afpj]

There seems to be lots of advice regarding cooling system bleeding on our engines. It's actually not that difficult to understand looking at the hoses under the hood. With our style cooling system the surge tank does all the work. The surge tank is a sealed system with an extra air space hose connected to the radiator that provides a path for escaping air. Essentially there is no special procedure to bleed the cooling system. Just drive the vehicle like normal.

From service manual:

That is from a post by matahoe in another thread with the exact same title. It appears that the upper hose routing which is just the airspace hose, if routed incorrectly and dips below a certain level it could pull in coolant. We actually might have a winner here.

 

[Chiller449]

I took this opportunity to get acquainted with my own 2005 Yukon cooling hoses. The unused hose mounting clip you mentioned holds the hose going to the throttle body on mine. I noticed you have the hose from the radiator to the upper surge tank routed below the engine air intake. Mine is routed over the top of the air intake much the same as another posters photo. Just for the heck of it try rerouting that.

I don't remember you saying where your surge tank fill level is. Just now I noted mine is just slightly higher than the cold fill level mark at the middle of the tank , at what looks like a seam left from manufacture.

You mentioned replacing a fan clutch. My Yukon has none, I have electric fans. I run the Torque Pro app and my normal operating temp is right about 190. I just now let it idle until at full operating temperature[ and observed no fluid flow through the upper surge tank hose. Perhaps that hose is there as you say, as a safety to allow some flow under higher rpms when the thermostat is closed.

View attachment 212132
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I wonder if there’s something screwy with the radiator. Is that bigger radiator a factory option or completely aftermarket? Just thinking out loud. As others have said, with engine warmed up I don’t have flow into the coolant overflow tank on any active basis. It sits at a higher level than when cold but I don’t see coolant churning around, like if you were to look at your power steering reservoir with the engine running.

That is from a post by matahoe in another thread with the exact same title. It appears that the upper hose routing which is just the airspace hose, if routed incorrectly and dips below a certain level it could pull in coolant. We actually might have a winner here.

The radiator is aftermarket. But had great reviews. I think you guys are onto something about the houses not routed correctly. Here in a few hours I'll go out there and rout them correctly. I'll keep you all updated.

 

[Doubeleive]

I still think it could be pressure related also.....i'm not sure how the pressure part works it may only need to build pressure from the top port of the radiator (the capped off line)

 

[Chiller449]

It didn't work guys. I routed the houses like factory and I'm still getting coolant rushing into the surge tank from that top hose. I had the system pressure tested and they did find a leak on the water pump but the new pump fixed that. It still holds tons of pressure and heats up great if I plug that top hose. I embedded a video from YouTube that I made. You can clearly see coolant rushing into the surge tank.

 

[swathdiver]

It didn't work guys. I routed the houses like factory and I'm still getting coolant rushing into the surge tank from that top hose. I had the system pressure tested and they did find a leak on the water pump but the new pump fixed that. It still holds tons of pressure and heats up great if I plug that top hose. I embedded a video from YouTube that I made. You can clearly see coolant rushing into the surge tank.

Still running the green stuff I see. Not good.

 

[Chiller449]

Still running the green stuff I see. Not good.

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What's wrong with the green stuff? I heard that orange coolant is terrible. It turns to sludge over time. From what I've heard. Anyways I'm almost sure this is it. I'll take that top hose off this weekend and look into the nipple with a flashlight. I bet there is no orifice inside. I'll have to go back to a stock radiator unless they make some kind of adapter I can use.

 

[swathdiver]

What's wrong with the green stuff? I heard that orange coolant is terrible. It turns to sludge over time. From what I've heard. Anyways I'm almost sure this is it. I'll take that top hose off this weekend and look into the nipple with a flashlight. I bet there is no orifice inside. I'll have to go back to a stock radiator unless they make some kind of adapter I can use.

It's not made for these engines or radiators. It only turns to sludge when mixed with Dexcool or when Dexcool is mixed with ethylene glycol. Dexcool has higher operating temperatures and lasts longer. I posted a research article about it earlier this year somewhere on here.

 

[TJ Baker]

What is your cold fill level? You haven't overfilled, have you?Should be down at the seam. On my stock vehicle the hose seems to exit the radiator maybe just a bit higher than the coolant level at the tank.

It's hard to see in your video but the tank is stained a good deal higher than the cold fill mark.

Speculating that the coolant level will be roughly the same throughout the system, in my case the hose to the surge tank exits the radiator above the coolant level as shown by the surge tank level.

Of course, I could be totally grasping at straws here

 

[Chiller449]

It's not made for these engines or radiators. It only turns to sludge when mixed with Dexcool or when Dexcool is mixed with ethylene glycol. Dexcool has higher operating temperatures and lasts longer. I posted a research article about it earlier this year somewhere on here.

Thanks for the info. Not sure if I'll ever switch it back. I've had way too many bad experiences with dexcool. All my chevys and all my friends chevys are running it and no one has reported any problems yet.

What is your cold fill level? You haven't overfilled, have you?Should be down at the seam. On my stock vehicle the hose seems to exit the radiator maybe just a bit higher than the coolant level at the tank.

It's hard to see in your video but the tank is stained a good deal higher than the cold fill mark.

Speculating that the coolant level will be roughly the same throughout the system, in my case the hose to the surge tank exits the radiator above the coolant level as shown by the surge tank level.

Of course, I could be totally grasping at straws here

Cold level is right at the seam on the tank.



Gonna see if I greatly reduce the size of the tube if it will help. If not I'll just get an oem radiator and be done with it.

 

[bottomline2000]

Well one thing I see is the hose that splits off the water pump and runs to the heater core on the firewall is connected to the outlet of the heater core. Mine runs from the water pump to the passenger side connection. Yours is reversed. Not sure that would make a difference or if the heater core is directional or not..

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