f5fstop

#PIP4918: Oil Consumption On Iron Block Engines With Active Fuel Management (AFM) - (Jun 23, 2011)


Subject: Oil Consumption on Iron Block Engines with Active Fuel Management (AFM)


Models: 2007-2011 Chevrolet Avalanche, Silverado, Suburban, Tahoe

2007-2011 GMC Sierra, Yukon

With Engine RPO Code LMG or LY5 (Iron Block V8 with AFM)




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

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some customers may comment about engine oil consumption on vehicles with higher mileage (approximately 48,000 to 64,000 km / 30,000 to 40,000 mi).

Recommendation/Instructions:
If this complaint is encountered, perform an oil consumption test by following the latest version of 01- 06-01-011.

If the oil consumption rate is greater than 1 quart of oil every 2,000 miles (3,000 km), perform the steps below as necessary:

Step 1:
Inspect the induction system to ensure that it is assembled correctly and that there is no evidence that the engine has been ingesting dirty air due to a miss-assembled induction system.

Step 2:
Follow SI and the latest version of PIP4492 to ensure that the PCV system is functioning properly and that there is no sign of excessive oil in the intake.

Step 3:
If the steps above do not isolate the cause of this concern, this is most likely the result of sticking oil control rings. To correct this condition, perform the piston ring cleaning procedure as outlined in the latest version of 10-06-01-008 and re-evaluate the oil consumption by following the latest version of 01-06-01-011. The AFM pressure relief valve used on the iron block engine opens at a much higher RPM that it does on the aluminum block engine so it is not suggested to install the AFM pressure relief valve shield at this point.

If the oil consumption rate is still greater than 1 quart of oil every 2,000 miles (3,000 km) after performing the repairs above, inspect the intake and exhaust ports/seals for any sign of a valve seal concern. If no valve seal concerns are found, replace all 8 piston and ring set assemblies. Also install the AFM pressure relief valve shield that is listed in the latest version of 10-06-01-008 since the oil pan will be removed to replace the pistons and rings anyhow. Follow the SI Piston and Connecting Rod Assemble Procedure to properly install the new piston rings onto the new pistons. Depending on the engine that you are working on, the replacement rings may have different features than the original rings. Due to the great variation between equipment, machine shops, and technicians performing these repairs, we DO NOT recommend honing or deglazing the cylinder walls though.

This is just because it is generally unnecessary and can induce unnecessary cylinder wall and/or piston ring damage if it is done incorrectly and/or not cleaned thoroughly. The cylinder walls just need to be cleaned thoroughly with brake cleaner before the new piston and ring sets are installed.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.



GM bulletins are intended for use by professional technicians, NOT a ""do-it-yourselfer"". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

f5fstop

#10-06-01-008B: Engine Oil Consumption on Aluminum Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder) - (Mar 7, 2011)


Subject: Engine Oil Consumption on Aluminum Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder)


Models: 2007-2009 Cadillac Escalade, Escalade ESV, Escalade EXT

2007-2009 Chevrolet Avalanche, Silverado 1500, Suburban, Tahoe

2007-2009 GMC Sierra 1500, Sierra Denali, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL

2008-2009 Pontiac G8 GT

Equipped with Aluminum Block V8 Engine with Active Fuel Management (AFM) (RPOs LC9, LH6, L76, LFA, L92)

with Greater than 45,000 km (28,000 mi)




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

This bulletin is being revised to add the 2009 model year and new Correction information for the 2009 model year - left rocker arm cover replacement. Information has also been added after step 9. Please discard Corporate Bulletin Number 10-06-01-008A (Section 06 - Engine/Propulsion System).


--------------------------------------------------------------------------------
Condition
Some customers may comment about engine oil consumption of vehicles with higher mileage (approximately 48,000 to 64,000 km (30,000 to 40,000 mi). Verify that the induction system is assembled correctly and that there is no evidence that the engine has been ingesting dirty air due to a mis-assembled induction system. Also verify that the PCV system is functioning properly. If diagnostic procedures indicate that oil consumption is piston/piston ring related, verify that oil consumption is less than 3,000 km (2,000 mi) per liter/quart. If these conditions are met and oil consumption is less than 3,000 km (2,000 mi) per liter/quart, perform the service indicated in this bulletin.

Cause
This condition may be caused by oil spray that is discharged from the AFM pressure relief valve within the crankcase. Under most driving conditions and drive cycles, the discharged oil does not cause a problem. Under certain drive cycles (extended high engine speed operation), in combination with parts at the high end of their tolerance specification, the oil spray quantity may be more than usual, resulting in excessive deposit formation in the piston ring grooves, causing increased oil consumption.

Correction
2009 Vehicles Only
Important: This left rocker arm cover is NOT to be used on 2007-2008 vehicles because of the calibration of the PCV orifice being different in 2007-2008.

A new left rocker arm cover has been released for 2009 engines. Technicians should replace the left rocker arm cover with GM P/N 12642655. This rocker arm cover has relocated PCV drain holes that prevents PCV pullover into the intake manifold. Refer to SI for Valve Rocker Arm Cover Replacement - Left Side.

2008-2007 Vehicles Only


To correct this condition, perform the piston cleaning procedure as described in this document, and install a shield over the AFM pressure relief valve per the procedure outlined in this document. Monitor oil consumption after this repair to ensure oil consumption has improved to acceptable levels. If this repair does not correct the condition, it may be necessary to replace the piston assemblies (piston and rings) with new parts.

Important: It is critical in this cleaning process that the engine/fuel injector cleaner remain in the cylinders for a minimum of 2.5 hours to fully clean the components. The cleaner solution must be removed before a maximum of three hours.

•Verify the oil consumption concern following Corporate Bulletin Number 01-06-01-011F. If oil consumption is found, continue on with this bulletin.
•Remove the spark plugs and ensure that none of the pistons are at top dead center (TDC).
•Clean the pistons by putting 118-147 ml (4-5 oz) of Upper Engine and Fuel Injector Cleaner, GM P/N 88861802 (in Canada, use 88861804), in each cylinder. Allow the material to soak for at least 2.5-3.0 hours, but no more than three hours and then remove the cleaner. A suggested method of removing the cleaner is cranking engine over. Make sure to unplug the ignition coils and fuel injector before cranking the engine over. Also make sure that the painted surfaces are covered so no damage is done.
•Remove the oil pan. Refer to Oil Pan Replacement in SI.


•Remove the AFM valve (1).


•Install the new shield (1), GM P/N 12639759, and tighten the AFM valve to the oil pan to 28 N·m (20 lb ft).
Important: Ensure that the engine cleaner is thoroughly removed before reinstalling the spark plugs. Failure to do so may result in a hydro-lock condition.

•Reinstall the spark plugs. Replace the spark plugs if necessary due to full of carbon. Refer to the parts catalog.
•Reinstall the oil pan. Refer to the Oil Pan Installation procedure in SI. Replace the oil pan gasket if necessary. Refer to the parts catalog. Replace the engine oil if necessary.
•Re-evaluate the oil consumption. Document on the repair order. If the oil consumption is still greater than 0.946 L (1 qt) in 3,200 km (2000 mi), replacement of the pistons and rings will be required.





Important: Some minor scratches may be noticed on the cylinder walls during piston and ring replacement. If the scratch cannot be felt when running your finger nail over it, the scratch is considered normal wear and the block or engine should not be replaced.

Parts Information
Part Number
Description
Qty

12639759
DEFLECTOR-OIL PRESS RLF VLV (quantity of 3 per order) (07-08 Models Only)
1

88861802 (in Canada, use 88861804)
CLEANER, F/INJR 16 OZ LIQUID POUR (Upper Engine and Fuel Injector Cleaner) (07-08 Models Only)
3

12642655
COVER ASM-VLV RKR ARM (09 Models Only)
1

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Description
Labor Time

J7555*
Install AFM Oil Deflector and Clean Carbon from Cylinder
3.5 hrs

Install AFM Oil Deflector and Clean Carbon from Cylinder (4WD)
4.5 hrs

Install AFM Oil Deflector and Clean Carbon from Cylinder (G8 Only)
10.5 hrs

J7561
Rocker Arm Cover- Left Bank - Replace- (For 2009 Only)
0.6 hr

*This is a unique labor operation for bulletin use only. It will not be published in the Labor Time Guide.




GM bulletins are intended for use by professional technicians, NOT a ""do-it-yourselfer"". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.