Cracks on 706 heads?
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Teching In
Joined: Nov 2011
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Cracks on 706 heads? So has anybody had this problem? If so where do they crack and how prone are the 706 castings compared to others??? I'm trying to budget build a motor and then I hear about the heads could crack...
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Teching In
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TECH Apprentice
Joined: Jun 2009
Posts: 318
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From: Oklahoma
The 2006 ( call Scoggin Dickey to confirm) are the model year that had issues. Something to do with the tooling. The cores to be exact. With that said I have used a few sets with no issue, but a set of lingenfelter heads came threw a friends shop and was pushing water on the engine. My friend pressure tested the heads and found no issue, so back on the engine they want with new gaskets. With in a couple weeks they where back with a very upset customer. With a further examination of the head they were found to be cracked at the bolt hole.
GM did have a service bulletin about these heads that have the battery emblem ( investment cast I think). Not all heads with this emblem are bad only the truck heads of 2006 and only some. It is a crap shoot if you'll have problems but agin it was only one year and I can't find my GM bulletin I had.
Hope this helps
GM did have a service bulletin about these heads that have the battery emblem ( investment cast I think). Not all heads with this emblem are bad only the truck heads of 2006 and only some. It is a crap shoot if you'll have problems but agin it was only one year and I can't find my GM bulletin I had.
Hope this helps
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From what I understand it could happen to any 706's that were made @ Castech which has a logo on top of 1 of the ports. The logo is a C with something in the middle or something like that . I know the C is easily identifiable .
This is the head in question.
If the cylinder head(s) is a Castech casting (1), inspect the area around the five oil drain holes for witness marks indicating coolant seepage over time (2).
If No evidence of coolant loss is found on inspection of Castech casting cylinder head(s), follow normal diagnostic procedures in SI to determine the cause of the coolant loss.
Russ Kemp
If the cylinder head(s) is a Castech casting (1), inspect the area around the five oil drain holes for witness marks indicating coolant seepage over time (2).
If No evidence of coolant loss is found on inspection of Castech casting cylinder head(s), follow normal diagnostic procedures in SI to determine the cause of the coolant loss.
Russ Kemp
Teching In
Joined: Jul 2013
Posts: 39
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From: Huntersville, NC
Castrch heads See if this link helps. This explains the problem and where to look.
http://ww2.justanswer.com/uploads/Bl...t_loss_5.3.pdf
http://ww2.justanswer.com/uploads/Bl...t_loss_5.3.pdf
I've seen a couple pick ups with this problem. There was signs of water when doing oil changes. Oil extra nasty with chunks, even at regular intervals. Wasn't like milkshakes on the ones I saw, but you could definitely tell something was up.
Teching In
Joined: Jul 2013
Posts: 39
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From: Huntersville, NC
Well, my '04 5.3 truck has castech heads, 90k miles, and there has never been a sign of water in the oil, but like your experience, the water looks like a milkshake in those cases where coolant gets in the oil.
So, like the bulletin says not every castech head, but they were the only heads that had the problem. YOu may not have a problem even with castech heads.
So, like the bulletin says not every castech head, but they were the only heads that had the problem. YOu may not have a problem even with castech heads.
On The Tree
Joined: Jan 2012
Posts: 198
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From: Canada NL
I have a 5.3 litre also with the 706 heads I got the heads off the motor now, I checked the topans looks good, I halled the basepan off last night there isn't no signs of coolant in the oil.I also have the battery logo on the head, I am going to send the heads off to the machine shop to get checked I guess..