04 Tahoe 5.3 Severe Sludge

[clcorrigan]

A friend has an 04 Tahoe 5.3L vin Z. He has been having oil pressure problems for the last week or so resulting in knocking. He changed the oil and found he had severe sludge buildup. Flushed the engine several times and still is having problems. I am sure he has already damaged the oil pump.

What is causing the sludge? Is there a common problem with the 5.3?

I have read about intake manifolds and cyl. heads. Also, a hole in the lifter which allows oil to squirt under the piston and cause sludge.

Anyone know of similar problems and a fix???

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No problem, someone just didn't change the oil enough. The only way to get it out is to run a couple runs of good clean oil through it, or tear it down and manually clean it. Maybe some MMO in the oil will help to.

[ColoradoSkiCountry]

What kind of oil has he been running? Some oils will sludge more than others.

[txab]

Is this vehicle new to your friend? Have you tested for coolant in the oil? The cracked head problem covered the '04 year. A few other things to think about:

 

Is the vehicle only being driven for very short trips? Is it reaching operating temperature? Does it have the OEM specified thermostat installed and is the thermostat working properly allowing the engine to reach it's proper operating temp so moisture can be burned off from the oil?

[dlstewart01]

Could be the castech head problem. Coolant in the oil will sludge one up bad. The 5.3 has a dry intake, no coolant goes through it with the exception of the throttle body.

 

These engines are not prone to sludge with proper maintenance. Name brand oils that are ILSAC GF5 API SM will not cause sludge unless not changed for a long while.

 

 

 

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

 

 

 

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)

 

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.

 

 

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).

 

Important: 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.

 

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