2003 Tahoe coolant system leak or head gasket leak?

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tomloans

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Sorry, work had me hemmed up the past few days.

That is 100% a clean spot from coolant. Being around the head bolt is the typical Castech failure. There's very little gunk because the leak is very small and only happens when it's up to operating temp and you caught it early. Compared to how bad my brother's was and it's running like a champ, I'd say yours would be just fine with new heads. I keep meaning to dig up the pics of what I found in his engine, but I see a lot of squirrels.
Thank you and I am supposed to get my Blackstone report tomorrow which will confirm our thoughts. The little puddle of clear fluid above the bald spot is pure coolant so it is pretty certain at this stage but I can wait one more day for the oil analysis. Thanks I will keep posting here for the person who is in need.
 
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tomloans

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You lose 2 HP and 7 ft-lbs of torque going from 706 to 799. That is all!

 
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tomloans

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706 VS 799
 

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  • 799 VS 706.JPG
    799 VS 706.JPG
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tomloans

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PLEASE NOTE I STARTED A NEW THREAD TO ADDRESS THIS QUESTION TO EVERYONE HERE...


I thought starting a new thread would be good for those who are having similar issues.

But here is the notes ( bad news ) from Blackstone...

"There is coolant in this first sample. Potassium and sodium are markers for antifreeze in testing, and
both are high. Sodium could be oil additive depending on the brand of 5W/30 being run, but potassium has
few other sources than coolant. Bearing wear (seen at copper and lead) is high too. Note the levels of each
that the universal averages show as typical for the 5.3L Vortec after ~5,400 miles of oil use. Stick to short
oil change intervals (like this) and be alert for coolant loses and symptoms of a bearing problem like

knocking and low oil pressure. Proceed carefully."

Copper is 132 should be about 19 ( after 5400 miles and my oil only had 900 )
Lead is 81... should be about 5 ( after 5400 miles and my oil only had 900 )

Sooo... Do I replace the engine or replace the heads and hope bearing wear will stop and live happily ever after with this engine...?

I have no idea if the bearings will stop wearing out once I get the coolant out of the system. This is my question, will bearing wear stop once it has started? Anybody have any experience with this please...?
 

iamdub

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PLEASE NOTE I STARTED A NEW THREAD TO ADDRESS THIS QUESTION TO EVERYONE HERE...


I thought starting a new thread would be good for those who are having similar issues.

But here is the notes ( bad news ) from Blackstone...

"There is coolant in this first sample. Potassium and sodium are markers for antifreeze in testing, and
both are high. Sodium could be oil additive depending on the brand of 5W/30 being run, but potassium has
few other sources than coolant. Bearing wear (seen at copper and lead) is high too. Note the levels of each
that the universal averages show as typical for the 5.3L Vortec after ~5,400 miles of oil use. Stick to short
oil change intervals (like this) and be alert for coolant loses and symptoms of a bearing problem like

knocking and low oil pressure. Proceed carefully."

Copper is 132 should be about 19 ( after 5400 miles and my oil only had 900 )
Lead is 81... should be about 5 ( after 5400 miles and my oil only had 900 )

Sooo... Do I replace the engine or replace the heads and hope bearing wear will stop and live happily ever after with this engine...?

I have no idea if the bearings will stop wearing out once I get the coolant out of the system. This is my question, will bearing wear stop once it has started? Anybody have any experience with this please...?

I wrote out a long answer in that thread, but I didn't really answer the "will bearing wear stop" part. At least, not directly.

Technically, no wear ever "stops". New bearings have a thin surface layer (called the "babbitt"). It's really thin and often wears to begin showing hints of copper within a few thousand miles. The cam and all should ride on a film of oil. So, once you get the watered-down oil out, I expect the wear to return to a more normal rate.
 
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tomloans

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I wrote out a long answer in that thread, but I didn't really answer the "will bearing wear stop" part. At least, not directly.

Technically, no wear ever "stops". New bearings have a thin surface layer (called the "babbitt"). It's really thin and often wears to begin showing hints of copper within a few thousand miles. The cam and all should ride on a film of oil. So, once you get the watered-down oil out, I expect the wear to return to a more normal rate.
Thanks. You and I are on the same page. I just purchased two 799 heads and the gaskets and bolts to replace everything below. Everything is about $1300.00 out the door including new bolts and all gaskets. This includes shaving the heads 0.20 to get them closer to the 706 heads. Not too bad. My labor is going to cost me about $40,000.00 but I am going to do it pro bono this time. LOL

Going to start tearing it down this weekend in anticipation. I am hoping that the wear was a one time event because I noticed a marked difference in coolant loss and some start up noise the last time I started it before I stopped everything. Hopefully a few oil changes later, I will run another Blackstone analysis and will all be well again. I need another 100K out of this SUV.

You have been really helpful and awesome. Thank you for your confidence and knowledge. I will post results as I get them. This is going to take some time. LOL
 

mattbta

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Thanks. You and I are on the same page. I just purchased two 799 heads and the gaskets and bolts to replace everything below. Everything is about $1300.00 out the door including new bolts and all gaskets. This includes shaving the heads 0.20 to get them closer to the 706 heads. Not too bad. My labor is going to cost me about $40,000.00 but I am going to do it pro bono this time. LOL

Going to start tearing it down this weekend in anticipation. I am hoping that the wear was a one time event because I noticed a marked difference in coolant loss and some start up noise the last time I started it before I stopped everything. Hopefully a few oil changes later, I will run another Blackstone analysis and will all be well again. I need another 100K out of this SUV.

You have been really helpful and awesome. Thank you for your confidence and knowledge. I will post results as I get them. This is going to take some time. LOL
I had to do it twice. One of my refurb 706 heads cracked in 500 miles. You should be immune with the 799's.

With the intake and heads off, you'll have the opportunity to replace maintenance items like knock sensors/harness, valley cover gasket, cam sensor (if leaky), oil pressure sensor, coolant temp sensor, steam port gaskets, exhaust mani gaskets, intake gaskets.

I pulled the oil pan just for desludging (new gasket and o-ring for pickup tube) also did lifters/trays/bolts since I was in there. I only had to remove the passenger manifold entirely - left the DS in place.

Be sure and grab the coolant drain plug off the passenger head to re-use.

And I bought the ARP head bolt thread chasers - worked well.

Good luck and hit us up if you have questions.

IMG_20200529_124901.jpg
 
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tomloans

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I had to do it twice. One of my refurb 706 heads cracked in 500 miles. You should be immune with the 799's.

With the intake and heads off, you'll have the opportunity to replace maintenance items like knock sensors/harness, valley cover gasket, cam sensor (if leaky), oil pressure sensor, coolant temp sensor, steam port gaskets, exhaust mani gaskets, intake gaskets.

I pulled the oil pan just for desludging (new gasket and o-ring for pickup tube) also did lifters/trays/bolts since I was in there. I only had to remove the passenger manifold entirely - left the DS in place.

Be sure and grab the coolant drain plug off the passenger head to re-use.

And I bought the ARP head bolt thread chasers - worked well.

Good luck and hit us up if you have questions.

View attachment 363591
Yes I am going to change all of these out. Have a gasket kit from Victor Heinz coming. Not going to drop the pan but everything else I have ready to go. Had a knock sensor go out already about a year ago. Rewired the bad one to the good one to trick the Chevy Computer so I can keep going. I have new ones ready to go and have the GM note on the silicon half circle for the knock sensor as well.
 

iamdub

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Thanks. You and I are on the same page. I just purchased two 799 heads and the gaskets and bolts to replace everything below. Everything is about $1300.00 out the door including new bolts and all gaskets. This includes shaving the heads 0.20 to get them closer to the 706 heads. Not too bad. My labor is going to cost me about $40,000.00 but I am going to do it pro bono this time. LOL

Going to start tearing it down this weekend in anticipation. I am hoping that the wear was a one time event because I noticed a marked difference in coolant loss and some start up noise the last time I started it before I stopped everything. Hopefully a few oil changes later, I will run another Blackstone analysis and will all be well again. I need another 100K out of this SUV.

You have been really helpful and awesome. Thank you for your confidence and knowledge. I will post results as I get them. This is going to take some time. LOL

Just happy to be relevant!
 

iamdub

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Yes I am going to change all of these out. Have a gasket kit from Victor Heinz coming. Not going to drop the pan but everything else I have ready to go. Had a knock sensor go out already about a year ago. Rewired the bad one to the good one to trick the Chevy Computer so I can keep going. I have new ones ready to go and have the GM note on the silicon half circle for the knock sensor as well.

I never understood building up a dam versus using sealant on the underside of the flaps. Maybe it's so they're more easily removable for servicing? I don't know. Maybe do both and be covered for anything.
 

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