- Read the entire procedure before removing the camshaft housing.
 
- The camshaft housing to the cylinder head gasket must be replaced
any time the camshaft housing to the cylinder head bolts are loosened or removed.
 
- During disassembly, be sure that the valve lifters are kept together
and identified in order to be reinstalled in their original locations.
 
- Remove the exhaust camshaft rear cover.
 
- Remove the exhaust camshaft rear cover gasket.
 
Important: Use the reverse of the tightening procedure when loosening the camshaft
housing to the cylinder head retaining bolts.
- Remove the exhaust camshaft housing to the cylinder head bolts.
 
Important: Leave two bolts loosely in place to hold the camshaft housing while
separating the camshaft cover from the housing.
- Push the cover off the camshaft housing by threading four of the housing
to the head retaining bolts into the tapped holes in the camshaft cover.
 
Important: Tighten the bolts evenly to prevent the cover from binding on the dowel
pins.
- Remove the two loosely installed camshaft housing to the head bolts.
 
- Remove the camshaft cover. Discard the seals.
 
- Loosely install one camshaft housing to the cylinder head bolt
to retain the housing during the camshaft and lifter removal.
 
- Remove the camshaft. Be careful not to damage the camshaft or
journals.
 
- Remove the valve lifters. Keep the valve lifters in order so they may
be reinstalled in the same location from which they were removed.
 
- Do one of the following to minimize lifter bleed down:
 
| •  | Store the lifters upside down on a level surface. | 
 
| •  | Store the lifters submerged in clean engine oil. | 
 
Important: 
|    •  | The valve lifters are not repairable. Replace the lifters if they
are faulty. Do not prelube on the camshaft cover seals because they will swell. | 
 
|    •  | Coat the lifter with Camshaft and Lifter Prelube GM P/N 12345501
or equivalent. | 
 
If new lifters are installed, add Engine Oil Supplement GM P/N 1052367
or equivalent to the engine oil.
- Remove the camshaft housing.
 
- Remove the camshaft housing gasket.