8.1L Changes in Heads , Bolts and Gasket for 2004 1/2 Engines - kw bolt consumption cylinder head intake oil

When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

The dealer may state that they changed the cylinder head on a L18 engine and the intake bolts are not long enough to engage into the head. Several changes have been made in the 8.1L L18 for 2004 1/2 model year. Changes include intake gaskets with locating pins (snouts), resulting in a counter bore in the head to retain the intake gaskets. When ordering a cylinder head for 2004 and prior model years a 2004 1/2 head will be supplied. Please see the applications component list below.

In 2004 1/2, the intake gaskets have been updated to include a locating pin or snout. If the dealer orders heads for a prior model year, new heads will be supplied and require the updated gasket and longer bolts for the 04 1/2 L18. The 2004 1/2 and prior heads can be differentiated by the intake bolts. The 2004 1/2 and newer engines have the black coated intake bolts and prior engines have silver intake bolts.

2001 - 2004 L18 heads use silver 65 mm bolts part number 12561518.

2004 1/2 L18 heads use an intake gasket part number 89017343 and black 72 mm bolts part number 11588980 with locator and snout.

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Please follow this diagnosis 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. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.

(01- 04 CHEVROLET 2500HD 2WD) and (01-04 CHEVROLET 3500 2WD) and (01- 04 CHEVROLET 2500HD 4WD) and (01- 04 CHEVROLET 3500 4WD) and (01- 04 GMC SIERRA HD 2WD) and (01- 04 GMC SIERRA HD 4WD) and (01 - 04 CHEVROLET SUBURBAN 2WD) and (01-04 CHEVROLET SUBURBAN 4WD) and (01- 04 GMC YUKON XL 2WD) and (01- 04 GMC YUKON XL 4WD) and (02 - 04 CHEVROLET Avalanche 2500HD 2WD) and (01, 02, 03 GMT 560)

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