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Discussion Starter · #1 ·
I have a 06 silverado with 5.3 i think i may be loosing antifreeze. Keeping a eye on it now. And i dont see any puddles under my truck. So my guess is possible cracked head. What are my options? I wanna get a cam as well if i do have to get heads. So what options are available for me?
 

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I have this problem on a 4.8
I've died it, checked everything I could possibly find and nothing. No idea where it goes.
 

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Discussion Starter · #3 ·
My buddie has a 03 5.3 and he had the problem. Wouldnt show up in oil or anything but he had a cracked head and cuz it went so long before being found he had to get a whole new engine. Granted if it came to it i wouldn't have a problem putting a 6.0 in it haha. Just would be nice to know with the weather slowly going down hill.
 

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Your 06 would not have the Castech head problems. Could be the water pump leaking.
 

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There are a lot of LS based head companies out there - might want to contact Texas Speed, or look on Ls1tech - lots of companies to choose from.

If you had the 6.0 - I would recommend a set of CNC LS3 heads.
 

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Discussion Starter · #8 ·
I thought the castech was earlier years?
They are.
There are a lot of LS based head companies out there - might want to contact Texas Speed, or look on Ls1tech - lots of companies to choose from.

If you had the 6.0 - I would recommend a set of CNC LS3 heads.
I wish i had a 6.0 but only have a 5.3 im wanting to do the nnbs intake swap as well
 

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Are you replacing the heads regardless of whether they are cracked or not?
 

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Just buy a set of used 799 heads at the junkyard or ebay and have them rebuilt and mill them .030" so you can run the nnbs intake manifold
 

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If in fact antifreeze is getting into the oil, the longer you wait the more your bearings will hate life... And at that point why put money into that motor?
 

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I would check your water pump. I doubt your issue is the heads.
 

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There are a lot of LS based head companies out there - might want to contact Texas Speed, or look on Ls1tech - lots of companies to choose from.

If you had the 6.0 - I would recommend a set of CNC LS3 heads.
recommending a set of LS3 heads is a bad suggestion.
cathedral will keep the low end that these heavy trucks need.
if his truck sits at 6000rpm all the time then yes some LS3 heads would be fine
 

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Just buy a set of used 799 heads at the junkyard or ebay and have them rebuilt and mill them .030" so you can run the nnbs intake manifold
you don't need 799s to run the NNBS intake, nor do u have to mill them to run it. You can bolt up the NNBS to 706s no problem.
 

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I would check your water pump. I doubt your issue is the heads.

Listen to this. I had to replace the heads on my 04 silverado 5.3 due to the castech head problem but I think they stopped them in 05 or 06. Your problem may be else where and cheaper to fix than you think. Try pulling off the valve covers and seeing what the oil looks like before just replacing the heads hoping that's the problem.


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Can i run 799s on a nbs intake?
yessir. they all bolt up the same and accept the center bolt valve covers u have. I would mill them atleast .030" tho since they have bigger chambers than 706s. If you were to bolt them up as is, then youd be dropping ur compression ratio.
 

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yessir. they all bolt up the same and accept the center bolt valve covers u have. I would mill them atleast .030" tho since they have bigger chambers than 706s. If you were to bolt them up as is, then youd be dropping ur compression ratio.
truth
 
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