Valve Stem Seals

REPLACEMENT

Due to the pressure differential that exists at the ends of the intake valve guides (atmospheric pressure above, manifold vacuum below), oil is drawn through the valve guides into the intake port. This has been alleviated somewhat since the addition of positive crankcase ventilation, which lowers the pressure above the guides. To reduce blow-by, Subaru employs valve stem seals which must be pressed (or tapped) into position over the valve stem and guide boss.

NOTE: When installing seals, ensure that a small amount of oil is able to pass the seal to lubricate the valve guides. Otherwise, excessive wear may result.

Factory seals should be replaced if the seal lip is damaged or the valve is removed.

1. Remove the cylinder head from the engine.
2. Remove the pushrods and valve rockers.
3. Using valve spring press assembly (899724100) or its equivalent, compress the valve spring and remove the valve spring retainer key.

   Fig. 2: Install seals over guides by pressing them on until arrowed dimension is shown

4. Mark each valve and spring to prevent confusion during installation.
5. Remove the oil seals from over the valve stems and guide bosses with a pair of pliers

   To install:

6. Lubricate the new seal prior to installation.
7. Using oil seal installer 898858600 or equivalent press the seal onto the valve stem.
8. Install the valve springs and retainer keys.
9. Install the rockers and pushrods.
10. Install the cylinder heads.