Engine - Abnormal Oil Consumption or Detonation

Bulletin No. T 83-41 File In Group 6A
Number 31
Date Feb. '83

INTAKE VALVE SEALS - 4.1L V-6 ENGINES

LARGER AND SMALLER DIAMETER SEALS:

Abnormal oil consumption or detonation experienced on 1980-1982 Cadillacs equipped with 4.1L V-6 engines may result from valve seals that have "lifted" off the valve guide. To correct this condition, a new smaller diameter intake valve seal (P/N 25516279) should be installed which will reduce the possibility of the seals lifting off the valve guide (see illustration). Since the cylinder head valve guide outside diameter must be reduced from .605 to .552 to accept the new seal, it will be necessary to rework the valve guides to the new smaller diameter prior to the seals installation. A valve guide cutting tool such as the KL1440, or equivalent, will be required to reduce the valve guide outside diameter to the new dimension, and is available from the following address:

*K-Line Industries, Inc.
315 Garden Avenue
Holland, Michigan 49423
Toll Free 1-800-253-2648
(Michigan Only 1-800-632-4595)

SERVICE PROCEDURE

1. Remove cylinder head and valve assemblies as outlined in the Service Manual. (For your information, the Service Part Number for the new cylinder head with smaller diameter intake valve seals is 25516366.)

2. Remove all intake and exhaust valves from cylinder head. (This is necessary to eliminate possibility of metal chips from cutting tool becoming lodged in exhaust valve guide mechanism.)

3. Insert valve guide cutting tool in chuck of 1/2" electric drill (low speed drill).

4. Place cylinder head on clean working surface, oil tool pilot and insert it into intake valve guide.
5. Apply steady pressure to cutting tool. Machine valve guide until small cutter block in tool has cut chamfer on top of valve guide.

6. Thoroughly clean cylinder heads and guides.

7. Remove any burrs from valve stems and guides with a fine stone or crocus cloth.

8. Oil valves and insert them into guides.

9. Install new seals on intake valves and other valve guides as outlined in the Service Manual.

10. Reassemble balance of cylinder head assembly - reinstall on engine.

WARRANTY INFORMATION

For warranty purposes, use labor Operation J0520, J0521, or J0527 at published time for specific model and year and add:

0.5 hour for one cylinder head gasket 0.9 hour for both cylinder head gaskets

* "We believe this source and their equipment to be reliable. There may be additional manufacturers of such equipment. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or equipment from these firms or for any such items which may be available from other sources."