Coolant

[jim664]

I am a new guy on here and need some help. I got a 05 sierra crew cab z71. It has 130,000 miles on it and coolant issues. About two weeks ago my temp started climbing over 210, and I was low on coolant. I poured about 2/3 of a gallon in it to fill it back up. Yesterday I poured another half gallon in, and today another half gallon(drove about ten miles today). There are no leaks anywhere(water pump, hoses, reservoir, radiator, etc.). The oil is not milky and no smoke. Where is the coolant going? thanks

[dlstewart01]

06-06-01-019B: Information on Gradual Coolant Loss Over Time with No Evidence of Leak Found - (Jun 12, 2007)

 

 

Subject: Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found

 

 

Models: 2004-2006 Buick Rainier

 

2001-2006 Cadillac Escalade Models

 

2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, TrailBlazer Models

 

2001-2006 GMC Envoy, Jimmy, Sierra, Yukon Models

 

2001-2004 Oldsmobile Bravada

 

2005-2006 Saab 9-7X

 

with 4.8L or 5.3L VORTEC® GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z -- RPOs LR4, LM7, LH6, L33, L59)

 

 

 

 

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This bulletin is being revised to include engine RPO L59. Please discard Corporate Bulletin Number 06-06-01-019A (Section 06 - Engine/Propulsion System).

 

 

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Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

 

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

 

Important: If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

 

Refer to the following illustrations on how to identify Castech casting and/or the very specific areas of the cylinder head(s) for a coolant leak from porosity.

[jim664]

06-06-01-019B: Information on Gradual Coolant Loss Over Time with No Evidence of Leak Found - (Jun 12, 2007)

 

 

Subject: Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found

 

 

Models: 2004-2006 Buick Rainier

 

2001-2006 Cadillac Escalade Models

 

2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, TrailBlazer Models

 

2001-2006 GMC Envoy, Jimmy, Sierra, Yukon Models

 

2001-2004 Oldsmobile Bravada

 

2005-2006 Saab 9-7X

 

with 4.8L or 5.3L VORTEC® GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z -- RPOs LR4, LM7, LH6, L33, L59)

 

 

 

 

--------------------------------------------------------------------------------

 

This bulletin is being revised to include engine RPO L59. Please discard Corporate Bulletin Number 06-06-01-019A (Section 06 - Engine/Propulsion System).

 

 

--------------------------------------------------------------------------------

 

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

 

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

 

Important: If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

 

Refer to the following illustrations on how to identify Castech casting and/or the very specific areas of the cylinder head(s) for a coolant leak from porosity.

 

thats scary

[[email protected]]

06-06-01-019B: Information on Gradual Coolant Loss Over Time with No Evidence of Leak Found - (Jun 12, 2007)

 

 

Subject: Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found

 

 

Models: 2004-2006 Buick Rainier

 

2001-2006 Cadillac Escalade Models

 

2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, TrailBlazer Models

 

2001-2006 GMC Envoy, Jimmy, Sierra, Yukon Models

 

2001-2004 Oldsmobile Bravada

 

2005-2006 Saab 9-7X

 

with 4.8L or 5.3L VORTEC® GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z -- RPOs LR4, LM7, LH6, L33, L59)

 

 

 

 

--------------------------------------------------------------------------------

 

This bulletin is being revised to include engine RPO L59. Please discard Corporate Bulletin Number 06-06-01-019A (Section 06 - Engine/Propulsion System).

 

 

--------------------------------------------------------------------------------

 

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

 

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

 

Important: If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

 

Refer to the following illustrations on how to identify Castech casting and/or the very specific areas of the cylinder head(s) for a coolant leak from porosity.

 

thats scary

 

 

Very much indeed!

[dlstewart01]

http://www.trustmymechanic.com/forum/f1t27...t_no_leaks.html

[jim664]

interesting link, but very scary.....any ideas on what brand heads to use if mine are the crap ones

[dlstewart01]

Should that turn out to be your problem, You want the same casting number heads you have now, 799(or 243). But, you want to find a set that were not made by Castech. It's pretty simple, when you find a set, ask for pics to make sure they do not have the "bullet" Castech logo.

[gapost]

If you have the dex-cool, you probably won't see the milky oil. In the oil, it tends to make a black gunk. Two things you could do. Drain your oil and put a screwdriver in your drainplug hole and see if you can scrape out black gunk. I had so much in mine, it clogged up the drain hole. The other thing is to pull the rocker covers and look for chocolate pudding there. You probably have the castec heads and if you have the skills, can probably do the work yourself. The heads can be found on ebay (got mine from Texas) for about $200 each. If you are like me and do preventive maintenance and really get things in good shape, it will cost you about $1000 in parts. If you have the dealer do it, it will be $2000-$3000.

[jim664]

Yeah i got the dex cool. I did not realize it does not get milky. Did you pull your oil pan off to clean the crap out?

[jblakeney]

Also, slow coolant leaks can be gaskets....... Water pump gaskets on ls engines sometimes leak.... I had a slow leak and it took me several years to pin point it..... Two dealerships and an independent shop said it was not leaking. A friend that is a 20+ year GM tech, never looked at it told me it was the water pump gaskets.... Walked outside opened the hood felt around walked right back in told me the passengers side water pump gasket was bad....

 

Sure enough I pulled the pump and was going to change it..... That gasket had came apart.... and the orange rubber was gone from that gasket.

 

But the Castech heads do HAVE ISSUES.

 

Jbo

[gapost]

Yeah i got the dex cool. I did not realize it does not get milky. Did you pull your oil pan off to clean the crap out?

 

Heck yeah I did. There was about an inch of black sludge in the bottom, almost up to the pickup tube.