Engine overheating, coolant stuck?

[Meathead16]

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.

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..

 

[Fless]

Welcome to TYF from Colorful Colorado!

Avys are welcome here....

 

[Joseph Garcia]

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.

 

[Doubeleive]

If in doubt grab a infra red thermometer from harbor freight they are like $25, it's possible the temperature sensor is not working properly if everything else seems ok
as for it being an avalanche I wouldn't fret that at all once you pop the hood they are all the same....

 

[exp500]

You had/have air in system after tstat change= low coolant. Burp Air. Or even drill two small holes in tstat.

 

[Meathead16]

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

 

[Fless]

Do those heads have 210k on them?

 

[Meathead16]

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

 

[Meathead16]

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?

 

[Meathead16]

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

 

[Doubeleive]

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

I think you are putting the cart before the horse here,
even if the head had a hairline crack or any crack for that matter you would be loosing coolant, it wouldn't make it just overheat unless it was a huge hole and again you would be loosing coolant and blowing white smoke.
and you would most likely have coolant mixed in the oil.
not loosing any coolant and simply over heating indicates something is stuck (thermostat), very low coolant, air in the system or water pump failure, cooling fan failure, clogged radiator.

 

[Meathead16]

True... you right..

Sometimes I focus so much on preparing for the worst that I forget to hope for the best..

There have been morning start ups where I'll get a decent puff of white smoke but not everytime, just randomly here and there. I guess after pulling the valve covers is what convinced me that it had to be cracked heads. Which, interestingly enough, I found a "Remanufactured by Non OE" sticker on yesterday.

 

[Meathead16]

I changed the water pump and started her up and coolant level never went down again. Got close to op temp and none of the hoses were hot.. weren't even warm.

I live at an apt complex that isn't the friendliest to those who don't take their vehicles to a mechanic so I don't really have access to a garden hose or a place where I can go flushing out the system... so I was thinking.. would I there be any possible consequences of using a shop vac on the rad hoses to try and suck out whatever was in there? Could something implode on me or breach a seal or something? I'd hate to suck the head gasket ha

 

[Doubeleive]

I changed the water pump and started her up and coolant level never went down again. Got close to op temp and none of the hoses were hot.. weren't even warm.

I live at an apt complex that isn't the friendliest to those who don't take their vehicles to a mechanic so I don't really have access to a garden hose or a place where I can go flushing out the system... so I was thinking.. would I there be any possible consequences of using a shop vac on the rad hoses to try and suck out whatever was in there? Could something implode on me or breach a seal or something? I'd hate to suck the head gasket ha

that's essentially what the dealer use's is a vacuum machine however no telling how much vacuum pressure it is set for, it's risky at best.
if the hose's didn't even get warm that could be a stuck thermostat or radiator is really plugged up good or the hoses are not plumbed right or the return line from the radiator to the reservoir tank is feeding back to much coolant essentially defeating the system.

 

[Meathead16]

what if I somehow fashioned some sort of plunger device? Had one hose open into a bucket, let's say the lower hose, and in the upper hose a plunged in somehow to try and push it out? Or would same risks apply as the vacuum?
If water was moving at minimum the heater hoses would be hot right? Even with a closed tstat?

 

[Doubeleive]

what if I somehow fashioned some sort of plunger device? Had one hose open into a bucket, let's say the lower hose, and in the upper hose a plunged in somehow to try and push it out? Or would same risks apply as the vacuum?
If water was moving at minimum the heater hoses would be hot right? Even with a closed tstat?

I don't know I would drain and fill with water and then go find a place with a hose to flush it out or just have a place do it.
what does the temp gauge do when you have it running does it just get hotter and hotter? or what

 

[Meathead16]

It builds up normally, I cut the engine before I had a chance to see if it would actually overheat, reason being when I felt that all the hoses were cool, it made me wonder since there's no flow, and the coolant in the surge tank isn't being pulled into the engine, if the coolant temp sensor was actually submerged in coolant or not and if the reading was accurate or if it was reading air temp which if that was the case I'm sure I've way overheated the engine. I thought this might be the case because the engine is smoking and I can't find the source. Most likely it's just coolant steaming off the exhaust manifold from me making a mess when I drained it. (Seriously, there's a special place in hell for the bean counter at GM that took the radiator draincock away) But I tend to assume the worst and thought maybe I've warped the heads so much it's coming from there. It's weird it's like it's coming from everywhere but no where at the same time.. I've tried shining a light, taking a video, but it must be so hot it's a vapor or something and then once it's floating in the air for a second or two it cools down and condenses enough to mix with particles in the air and be visible. Pure speculation, I really don't know lol

When this started the temps would basically just run away and not stop until I killed the engine. After the tstat and me cleaning up the old water pump it would rise and after hitting 190 or so it would still climb, but not as fast.

 

[B-train]

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

You can try adding some K-Seal leak stop to the system. This stuff claims to stop head gaskets, etc and is a long-term fix. I used it in my 3 cinder diesel to stop weeping by the block heater because I didn't feel like pulling the fuel pump out for a stupid freeze plug......2 mowing seasons later and not one drop has left the system.

You can get it at any parts store. Blue bottle with orange writing. Put it in and run the truck without the cap on to try and allow more opportunities for the system to burp itself. It's a $10 try to buy some time

 

[Marky Dissod]

If you're going to 'suck' stuff from the cooling system, suck from each individual component SEPARATELY.
If you suck through two things - say, engine and heatercores - you may dislodge something from the engine and get that stuck WORSE in one of the heatercores.

If something is stuck in any component of the cooling system, probably wiser to replace that part.
If the 'clot' breaks into smaller 'clots', they may get lodged in other components that will need replacing.

Maybe you need an infrared temp measuring gun to find a sudden temp drop, may help you find a problem.

 

[Doubeleive]

It builds up normally, I cut the engine before I had a chance to see if it would actually overheat, reason being when I felt that all the hoses were cool, it made me wonder since there's no flow, and the coolant in the surge tank isn't being pulled into the engine, if the coolant temp sensor was actually submerged in coolant or not and if the reading was accurate or if it was reading air temp which if that was the case I'm sure I've way overheated the engine. I thought this might be the case because the engine is smoking and I can't find the source. Most likely it's just coolant steaming off the exhaust manifold from me making a mess when I drained it. (Seriously, there's a special place in hell for the bean counter at GM that took the radiator draincock away) But I tend to assume the worst and thought maybe I've warped the heads so much it's coming from there. It's weird it's like it's coming from everywhere but no where at the same time.. I've tried shining a light, taking a video, but it must be so hot it's a vapor or something and then once it's floating in the air for a second or two it cools down and condenses enough to mix with particles in the air and be visible. Pure speculation, I really don't know lol

When this started the temps would basically just run away and not stop until I killed the engine. After the tstat and me cleaning up the old water pump it would rise and after hitting 190 or so it would still climb, but not as fast.

the hoses are not really going to change feel much until it has cycled with the thermostat opening and even then they may only feel luke warm until it is driven. If the temp is normal at that point you are fine even if it is smoking as long as you are not loosing coolant and you have oil in it.
and unless it was severely not maintained and a bunch of rusty water came out when you flushed it then there is most likely no "clot" or blockage it's something else if it is still overheating