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Fat, bald guy.
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2000 Chevy Tahoe LT 5.3 with 230k miles.

I bought the tahoe with a blown head gasket, took it to the shop and had them rebuild the engine, once I started driving it I noticed it was using alot of antifreeze, so I researched it and came up with CASTECH heads. I drove it over 2k miles with nothing mixing in the oil just a leak of antifreeze I could not find. I checked he oil once a week to make sure water wasn't getting into the oil, last time I checked it I found the signs of water getting into the oil. Took it to a friends shop, he pulled the valve cover, we could not find the CASTECH symbol anywhere on the passenger side head (706 head). We did a pressure test, it was holding at at 12psi. I don't know what else to check or what else to do, and ideas??

Here is the passenger side cover....
 

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2000 Chevy Tahoe LT 5.3 with 230k miles.

I bought the tahoe with a blown head gasket, took it to the shop and had them rebuild the engine, once I started driving it I noticed it was using alot of antifreeze, so I researched it and came up with CASTECH heads. I drove it over 2k miles with nothing mixing in the oil just a leak of antifreeze I could not find. I checked he oil once a week to make sure water wasn't getting into the oil, last time I checked it I found the signs of water getting into the oil. Took it to a friends shop, he pulled the valve cover, we could not find the CASTECH symbol anywhere on the passenger side head (706 head). We did a pressure test, it was holding at at 12psi. I don't know what else to check or what else to do, and ideas??

Here is the passenger side cover....
If you had the engine rebuilt, take it back and make them fix it :shrug:
 

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It may have been covered up by all the sludge. My 04 silverado had the 706 castech heads and I started noticing lower than normal oil pressure. I pulled the valve covers and had the same thing. I replaced the heads myself with used 862 heads. I also dropped the oil pan and cleaned it out along with replacing the oil pickup tube and oil pump o ring. My truck only had 70000 miles on it too.


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has to be a cracked head...no coolant passing thru these intake manifolds. Youre gonna need a new/used set of head(s)....if the gasket had blown again, you wouldn't have that milkshake under the covers. Take it back to the shop, imo.
 

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Fat, bald guy.
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Discussion Starter #5
Problem with taking it back I already got a refund for the engine build because of problems, already had to replace a push rod because it broke and the timing set because it was sagging.I drove over 2000 miles with no water getting into the oil, not it has water in the oil. The mechanic is pulling the heads, he said it could be a bad spot on the block itself were the head mated to the block.
 

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If you had the engine rebuilt, take it back and make them fix it :shrug:

This. The rebuild had to have come with some sort of warranty more than 2000 miles. You should have taken it back as soon as you noticed it losing antifreeze. Take it back now for sure.
 

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head could've cracked after they installed...maybe they didn't torque them down correctly...maybe they didn't clean the head/block surfaces...removing heads, cleaning and inspecting them would be a good start to all this. good luck...sounds like a nightmare
 

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Wow, yeah that does suck. If it were me, I'd find a good, low-mile 5.3 and have that installed.

Are both heads 706?
 

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you almost have to take the rocker stand off and look right under it....kinda hard to see the lil battery looking logo if you don't remove the rockers and stand
 

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With 230k miles, chances are if they were castech heads they went bad long ago. But, they don't have to be castech heads to be cracked.
 

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did u do the pressure check cold or hot? could be a tiny crack that expands when hot but holds some psi when cold?
 

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wont hurt anything with the cover off...not like it sprays oil everywhere...oil barely oozes out the pushrods at idle.
 

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Fat, bald guy.
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Discussion Starter #19
wont hurt anything with the cover off...not like it sprays oil everywhere...oil barely oozes out the pushrods at idle.
He called me about an hour ago he was in the middle of taking the heads off, maybe with them off he can get a better look at them, if it does turn out to be the heads i'm going to replace them with a set of 862 heads...
 

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id get 243/799s and have them milled .030" those heads flow WAY better and would be a nice upgrade.
 
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