Engine overheating, coolant stuck?

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Meathead16

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New guy here, have read a lot, but never joined cause I didn't want to be the odd man out seeing as I don't have a Tahoe or Yukon, but anytjme I'd search for.. well.. anything really, this site was always first page, and has definitely helped me out a lot. Then I saw you had an 'Other' section. :D

I have an 05 Avalanche LT Z71, 5.3. 210k, that overheated on me one day after a very short drive.. maybe a mile or two. The temp gauge didn't max out but I got the message on the DIC. Was on a 3 lane rd no shoulder so had to keep driving another 30 seconds or so before I could pull over. The cooling fans were working (electric), the hoses were hot.

I figured it was the tstat not opening as there weren't any leaks that I could see and no coolant loss. Oil looks good. Changed tsat. Used the procedure shown in attached pics to refill. It's for an 02 but figured it would apply just the same. Maybe not?

Coolant level never dropped in the surge tank even though I had plenty left to add. Instead, it started smoking and a good quart at least boiled over and out onto the ground.

Never had an issue before, temp gauge had never been above ~190. I'm thinking water pump but they usually leak out the weephole, at least a little bit, right? Could the impeller have separated somehow? I did see on the tensioner pully what was either oil and dirt buildup, or possibly belt material. Belt is probably due for replacement, but alternator and PS pump are fine so would a bad belt really only not drive one component? I hate throwing parts at an issue and praying for the best, especially after I went against my better judgement on getting the thermostat but for <$10 I said f' it. Well it f'd me back ha. I read that the tstat is not supposed to be replaced by itself but a new inlet should be installed with it, which I did not do. Is that important?

Could it be a restriction in the cooling system? I've only had the truck a few months and was unable to procure any meaningful service history. I have discovered, however, that the coolant level sensor has vanished, and I can't find the connector that went to it..
 

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Joseph Garcia

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Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I cannot personally help you with your question; however, other members on this Forum that are much more knowledgeable than me will chime in.
 
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Meathead16

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I had to back burner this for a minute but now with a change in situations, of course, it's now a dire situation of sorts lol. I've read about the Castech head issues for these model years. I have a 706. Pulled the right valve cover (will pull the left later today if I can) and found what I was hoping not to.

I was trying to find a crack somewhere but couldn't really see anything.


Even with a borescope, I couldn't pinpoint a definitive origin (pics attached). The head of the scope was too big to fit any deeper.

It's a long story, but I really need to get this truck on the road again asap, and have very little extra funds to do so. A new head really isn't within the time constraints I'm under, so I'm wondering if anyone else that has had this happen to them was able to "fix" it for a little while? It doesn't have to be permanent, just something for a few months even would be a life saver. Are products like bars leak or something like that worth consideration? Should I just JB-Weld it bro? My question there would be where would I even jb-weld?

Castech wronged these engines with their faulty heads, and I would be wronging it further with a cheap bandaid..
I know the "right" way to do it, and no, two wrongs don't make a right....
but three lefts do ;)
 

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Meathead16

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The previous owner said that the entire engine was replaced at 190k. The engine numbers match the vin tho so it's still the original. He was kinda "out there" though and in retrospect I seriously question literally everything he said.. live and learn..

It's possible just the heads were replaced at 190k, or whenever, but I can't be sure.

Essentially it's history is unknown. I bought it with 208k about 6 months ago
 
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Meathead16

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Took the drivers side valve cover off tonight:

I edited the videos to play 2x as fast to reduce the upload size/time. Play at half speed to for normal speed for less shake. Anyone know what's up with the blue stuff?


Main area of concern: is this really the type of stain the coolant leaves when it dries?

 
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Meathead16

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Bump - is there anything I can do to squeeze a little time out of this engine without replacing the heads?
 

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