5.3 coolant leak

[jigsaw]

Howdy folks,
I have been trying to find out the answer to my problem for a while. I have been looking at multiple forums and searching the net for answers but am getting so many mixed answers. I have a 2000 sierra 1500 with a 5.3 engine and I have a coolant leak that has steadily been getting worse. I have not been able to find a spot on the ground that shows where it would be leaking and a while back a pressure test was done and it showed no leak. I thought it might be the intake manifold gasket because several inches below the throttle body there is a small ledge that appears to be loaded with gunk and sludge, maybe a mixture of dust and coolant because it smells sweet when I picked some up. But I have read that the 5.3 has no coolant running through it because it is a dry intake and so now I am at a spot where I am stumped. I am hoping that someone who has more experience than me could direct me correctly. Is there any spot toward the top of this engine where coolant could be leaking and running down and evaporating where I am not seeing it? I have checked my water pump and it is fine, I had it replaced a few years ago. I am definitely stumped on this one and any help would be greatly appreciated.

 

[blackSLT14]

I had a similar problem with a 2000 Tahoe 5.3. Come to find out one of my heads has a tiny little crack and its slowly leaking coolant into my oil. there are websites you can order a oil analysis kit from and they will let you know what's all in your oil. But yeah, about twice a year a low coolant light comes on and I have never had a leak. Hope this might help.

 

[winger870]

There are pitures with this bulletin but they did not post. This may help you with your problem. I know it is for GM's 2001 and newer.



Bulletin No.: 06-06-01-019B

Date: June 12, 2007

INFORMATION
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(R) GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z - RPOs LR4, LM7, LH6, L33, L59)

Supercede:

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.

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

Cylinder head(s) location of the Castech manufacturing casting logo (1).







Close up view of the cylinder head(s) showing the Castech manufacturing casting logo (1).







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.







The crack location can be found in any of the five cylinder head(s) oil drains. This can be seen as a clean or shiny area, on an otherwise stained surface (1). Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area. If inspection reveals evidence of coolant witness marks (1), replace the entire cylinder head(s) assembly

 

[jigsaw]

Thanks guys, I will be tearing it apart soon to check for the dreaded castech logo. I am not looking forward to this.

 

[G-732010]

fukk...lol...