Engine not reaching operating temperature

[Chiller449]

Can't see any pictures. Does your serpentine belt wrap around the pump like this?

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Yep, so my water pump is definitely not turning backwards. well, I'm out of ideas. I guess my last step is to take it to the dealer. Ive taken it to a couple local shops and they have no idea. Any other ideas guys? I might just leave that hose plugged permanently if i cant figure this out.

 

[swathdiver]

How about your radiator cap? Have you replaced or tested it?

 

[Doubeleive]

i'd say take off your intake tube and the top fan shroud and post up some pictures of how everything is connected, something is screwy

 

[Chiller449]

How about your radiator cap? Have you replaced or tested it?

I have not, But i dont see how it could cause a problem. It heats up just fine and holds alot of pressure if i keep that tube plugged. Ill have it tested though.

i'd say take off your intake tube and the top fan shroud and post up some pictures of how everything is connected, something is screwy

Ok ill see if i can get some better pics tomorrow.

 

[Fless]

@Chiller449, this is how my 2004 is routed. The clamped line at the surge tank goes to the top radiator port. The lower radiator port hose runs up alongside the upper radiator hose back to the TB. Couldn't tell if yours was run that way from your pics.

 

[TJ Baker]

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.

 

[Fless]

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.

Rerouting the upper hose over the air intake would be a good thing to try, as well as bringing up the lower hose from the radiator (going to the throttle body) and clipping it into the clip on the fan shroud.

If you want other pics, let us know what you'd like to see.

 

[afpj]

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.

 

[Doubeleive]

nothing really makes any sense, have you done a pressure test?. you said you took it to a mechanic and they couldn't figure it out did they do a pressure test?, maybe there is a crack in the upper part of the reservoir tank? bad cap like James mentioned? looking at the picture of your reservoir tank again it looks like where you have the capped off line connected there is some coolant/corrosion under it and it looks like there may be cracks in the tank right there? not sure that would cause the problem but I would take a closer look. I would even go so far as to guess since capping that line makes pressure and then it works right, then the reservoir tank/cap is maybe the problem, a new tank and cap aren't much money wise for like a dorman I think a dorman is like $25-30 and maybe slightly more at the dealer for a oem one

 

[bottomline2000]

@Chiller449, this is how my 2004 is routed. The clamped line at the surge tank goes to the top radiator port. The lower radiator port hose runs up alongside the upper radiator hose back to the TB. Couldn't tell if yours was run that way from your pics.


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I think u may have foumd the problem. If he's got this tube routed lower than the radiator top so it's probably pushing fluid which is why he's seeing flow from it and why the truck heats up when he blocks it. He's creating an open loop that is bypassing the thermostat.

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