Intake Valve Seals - Abnormal Oil Consumption
Number: 83-I-38
Section: 6A (VI)
Date: Dec., 1983
Subject: INTAKE VALVE SEALS FOR 3.8L ENGINES
Model and Year: 1978-84 MONZA, MALIBU, MONTE CARLO AND EL CAMINO
TO: ALL CHEVROLET DEALERS
This revises Bulletin 83-I-38 issued January, 1983 and reissued February, 1983. Previously issued copies should be destroyed.
LARGER DIAMETER SEAL:
SMALLER DIAMETER LATE TYPE SEAL:
A new smaller diameter intake valve seal went into production approximately December 1, 1982, on 3.8L engines (see illustration). The new seal will reduce the possibility of the seals lifting off the valve guide, which could result in abnormal oil consumption or detonation.
If either of these conditions is encountered, the new seals, P/N 25518390, should be installed. The seals should also be installed on the above engines whenever engine coolant (ethylene glycol), which can deteriorate the valve seal, is present in the engine oil or internal coolant loss is suspected. Since the cylinder head valve guide outside diameter was reduced to accept the new seal, it will be necessary to rework the valve guide to the new smaller diameter prior to its installation.
This can be done by removing the cylinder head and using a valve guide cutting tool such as the KL1440, or equivalent, which will 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, MI 49423
Toll Free 1-800-253-2648
(Michigan Only 1-800-632-4595)
NOTICE: An exchange program for badly worn or used tools (less pilot) is also available through K-Line Industries. Price of rebuilt tool (P/N 1443ADRT) is $17.50 plus postage. This price is based on manufacturers ability to rebuild returned unit.
Instructions for Machining Guides
1. Remove cylinder head and valve assemblies as outlined in the service manual.
2. Remove both 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 machining 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, removing any cuttings and carbon build up.
7. Remove any burrs from valve stems and guides with a fine stone or crocus cloth. At this point, valve guides should be checked for concentricity; valve guide opening centered in valve guide, and that there is sufficient stock left around the circumference of the valve guide to properly retain valve seals.
8. Remove excess carbon from valves, oil valves and insert them into valve guides.
9. Install new seals on intake valves and over valve guides using a deep well socket to ensure seal is on squarely and firmly seated.
10. Reassemble balance of cylinder head assembly - reinstall on engine.
For your information, service part number for the new cylinder head is 25516366.
*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.
Use applicable labor operation.