5/1/2003
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Cylinder head bolt replacement for 1997-2003 Ford 6.8L VIN S engines.
Engine Builders: The AERA Technical Committee offers the following information regarding cylinder head bolt replacement for 1997-2003 Ford 6.8L VIN S engines. This engine requires new replacement cylinder head bolts any time the head is installed.
Follow the procedure listed below after all components have been thoroughly cleaned and prepped. Ensure that all surfaces of the cylinder block, cylinder head, and gasket are free of any solid or liquid contamination and have been prepared for assembly using Motorcraft Metal Surface Cleaner, F4AZ-19A536-RA (or equivalent) solvent. Also ensure that all dirt is removed from the area surrounding the head and the block. Verify the cylinder head flatness and surface finishes are appropriate for the MLS (multi-layered steel) gasket seal.
For vans, the four center bolts must be installed in the cylinder head before placing the cylinder head on the block when the engine is in the vehicle. To install the cylinder head without damaging the gasket or the gasket-mating surfaces, lift bolts 1-4 slightly above the cylinder head gasket-mating surface and hold in place by using a large rubber band.
The new head bolt shanks and threads should be thoroughly cleaned, dried, and lightly lubricated. Oil the bolts and let oil drip for a minimum of 5 minutes as use of too much oil may cause hydraulic lockup in the bolt holes. Install the head gasket, the cylinder head and all of the NEW fasteners finger tight, and then tighten the bolts in the following three stages and reference the illustration shown in Figure 1.
- Tighten all bolts in sequence to 30 ft.lbs. (40 Nm).
- Rotate all bolts in sequence an additional 85°-95°.
- Rotate all bolts in sequence an additional 85°-95°.
NOTE: Steps 2 and 3 are not to exceed 190° total rotation.
As noted above, this engine requires head bolt replacement whenever the heads are installed. Until recently those bolts were only available from Ford, but now, AERA is aware of at least one aftermarket supplier of these head bolt fasteners.
Engine Builders: Complaints of an engine knock noise or lifter noise on 2000-2003 GM 4.8L, 5.3L, 5.7L and 6.0L engines have been lodged by machine shop customers. This noise is particularly troubling to customers because it is often noticed in new vehicles within the first 100-200 miles.
This noise, due to collapsed lifters, is most pronounced at cold start up and may diminish and return as the engine warms up to operating temperature.
This potentially disturbing engine noise is caused by a cut or distorted O-ring between the oil pump screen and the oil pump, that allows air to enter the oiling system.
To eliminate the noise, inspect the O-ring and replace it, if necessary. There are two different O-rings used depending on the type of vehicle. For code F and Y type car engines, use O-ring p/n 12557752 and for C/K Trucks, use O-ring p/n 1253963.