23-NA-020

Service Bulletin
Bulletin No.:
23-NA-020
Date:
April, 2024
TECHNICAL
Subject:
Oil Leak from Front of Engine
Brand:
Model:
Chevrolet
Corvette
Model Year:
VIN:
from
to
from
to
2023
2023
—
—
Engine:
Transmission:
5.5L
(RPO LT6)
—
Involved Region or Country
North America, Europe, Israel, Palestine, Japan, Thailand, Australia/New Zealand
Condition
Some customers may comment that there is a visible engine oil leak coming from
underneath the middle of the vehicle.
During inspection, some technicians may notice that there is a small oil leak coming from
the engine front cover area.
Cause
6267588
This condition may be caused by improper front cover bolt torque or inadequate sealer
adhesion at one of the six T-Joint locations.
– The oil leak can be found at the T-Joint location where the cylinder head meets the
engine block, or at one of the other T-Joint locations (shown n yellow) in the graphic
above.
Correction
Copyright 2024 General Motors LLC. All Rights Reserved.
To correct this condition, it will be necessary to install new front cover gaskets and follow
the revised RTV sealing procedure as noted below.
Page 2
April, 2024
Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
under this bulletin, including but not limited to
handling, deploying, preparing, classifying,
packaging, marking, labeling, and shipping
dangerous goods. In the event of a conflict between
the procedures set forth in this bulletin and the
laws that apply to your dealership, you must follow
those applicable laws.
Bulletin No.: 23-NA-020
Service Procedure
6550667
Bulletin No.: 23-NA-020
April, 2024
Page 3
Important: When performing this service procedure,
the intake manifold needs to be removed and
reinstalled. During installation, ensure that all 10
compression limiters are installed and present in their
correct positions before fastening the intake to the
cylinder head.
Intake Assembly left hand side shown (right side
similar).
Important: Ensure all front cover bolts are torqued in
proper sequence and to specification.
Refer to Engine Front Cover Replacement in the
Service Manual.
Additional Information
Important: Application of the RTV has changed.
Please refer to the picture and steps below for proper
RTV application.
6002788
Note: The sealing surface must be clean and free of
contaminates prior to applying the RTV sealant. Do not
touch the sealing surface once it has been cleaned.
1. Clean the sealing surface at the T-Joints (1 and 2)
with low VOC brake cleaner, then wipe dry with a
clean lint-free cloth.
Note: Do not allow RTV to skin over. The engine front
cover gaskets and engine front cover must be installed
within 8 minutes of RTV application.
2. Apply a 5 mm wide x 15 mm bead of sealant to the
4 T-Joints (1) between the cylinder head-to-engine
block and the engine block-to-lower crankcase.
3. Apply a 5 mm wide x 25 mm bead of sealant to the
2 T-Joints (2) between the cylinder head-to-engine
block and the engine block-to-lower crankcase.
Page 4
April, 2024
Bulletin No.: 23-NA-020
Parts Information
Causal Part
Description
Part Number
Qty
X
GASKET, ENG FRT CVR
12707585
1
X
GASKET, ENG FRT CVR
12707584
1
X
GASKET, ENG FRT CVR
12707583
2
SEALANT
19369831 (U.S) 19369832
(Canada)
1
N/A
SEAL, OIL TRFER TUBE O-RING
12697070
1
N/A
SEAL, OIL TRFER TUBE O-RING
12697071
1
N/A
SEAL, O.PMP HSG O-RING
12670121
1
N/A
GASKET, PCV OIL SEP
12695546
1
N/A
GASKET, EXH MANIF
12673594
2
N/A
GASKET, INT MANIF
12668302
8
N/A
N/A
FILTER KIT, OIL
12730579
1
N/A
PIPE, FUEL FEED INTER RIGHT
12663298
1
N/A
PIPE, FUEL FEED INTER LEFT
12663297
1
N/A
SEAL, W/PMP O-RING
12668422
1
N/A
BOLT, R/AXL SHF
11601876
12
N/A
SEAL, A/C CMPR HOSE
13418808
1
N/A
SEAL, A/C CMPR HOSE
13418809
1
N/A
BOLT, CR/SHF BALR
11547975
1
N/A
SEAL, CM/SHF HSG CVR (right)
12672530
1
N/A
SEAL, CM/SHF HSG CVR (left)
12672531
1
N/A
GASKET, CM/SHF POSN ACTR
MAGNET
55499462
2
N/A
SEAL. SPLG SHLD
12672529
8
N/A
GASKET, CTLTC CONV
12672379
2
Warranty Information
For vehicles repaired under warranty, use:
Labor
Operation
4063610
Description
Labor Time
Engine Front Cover
Replacement
Use
Published
Labor
Operation
Time
Version
2
Modified
Released April 27, 2023
Revised March 26, 2024 – Added a graphic and first Important statement under Service
Procedure and updated Parts Information section.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
WE SUPPORT VOLUNTARY
TECHNICIAN
CERTIFICATION