Cummins Confidential
1

Valve Spring Failure (93329)
Background
• RMEP received reports of 8 B6.7 engines with dropped valves suspected
to have been caused by broken valve springs.
• Three failures were in transit to end customers and one BIS failure in
transit to US.
• Two additional engines with the same failure mode found in another
OEM assembly plant.
• All 8 failures used ID 21 Cylinder Head 5361605 which uses spring
5303406.

Failure Mode
• Dropped valve due to broken valve spring.

Investigation
• Suspect range identified and shared (1018 engines)
• Released engines not using springs from the same supplier lot
• Failed engines in process of being returned to RMEP for analysis.
• 5 of the 8 failed springs are returned from the field and reviewed at
RMEP, Supplier or Cummins Tech Center
• Received non-failed springs from same ESNs with failures for analysis.

Corrective Actions Completed
Step 3 ICA:
• Dock closure issued on all B6.7 Engines.
• Identified suspect spring lot #’s and sorted loose inventory to ensure no further
builds using these lots.
• Completed 850 minute aggressive cycle-6 test on B6.7 engine using these
same part #’s and conducted partial teardown. - No Concerns Identified.
• Received material certifications for spring lots in house from supplier.
• Received parts with additional 100% visual inspection using magnifying glass
• 30 parts from each process per lot verified using microscope from supplier.
• ESN first 74713909.
Step 6 PCA:
• Supplier removed temporary tote and added metal guide to prevent springs
from missing oven conveyor from previous process conveyor (August 21)
• Field action requested with replacement of suspect valve springs (Ongoing)
• Replacement of suspect valve springs in engines/vehicles at OEM plants
(Ongoing)

Next Steps
• Spring supplier to recreate failure and complete durability testing to understand
failure rate
• Supplier to implement fixes to avoid temporary processes

Root Cause
• Analysis shows radial cracks on the inner diameter of the springs.
• Supplier confirmed radial cracks were caused by delay between coiling
and stress relieving oven
• Delay caused by supplier using a temporary tote to catch springs after a
backup conveyor was introduced

1

CAMPAIGN Work-order:
ASSEMBLY / CAMPAIGN:

(For this campaign use Dept. # /

)

Please supply copy of all cost associated with the campaign to (Campaign
Lead –
)
CAMPAIGN FACTORY WORKORDER
Factory Work Order Number: 5303406
Total Cost: TBD
Contact person:
Supplier: NHK
Part Name: Valve Springs
Part#: 5303406
Description of Problem: Early failures of valves springs led to identification of
suspect lot of valve springs and suspect ESN list.
Description of Work Performed: Remove suspect valve springs and replace
with new springs. Return suspect springs to:
Attn:
Cummins Inc
Dock 72 RL407
500 Central Ave.
Columbus, IN 47201
ESTIMATED TOTAL COST: TBD
When documenting time associated with this campaign, please use the work
order number “
” to capture all labor costs. The actual labor dollars
will continue to be charged to the individual's home team. However at monthend, a journal entry can be made to charge the cost center and account for
campaign activities related to the rework of valve spring and Assembly lost
units.
Any purchase orders written to purchase items or other charges associated with
campaign should reference the campaign name in the body of the purchase order
and should be charged to dept/account / 4
.
Date ___OCT 22 2020

The purpose of this document is to provide instructions on replacing valve springs on
identified engines.

After verifying that the engine needs valve springs replaced, perform the following
action:
1. Replace valve springs per procedure 002-016 Valve Guide Seal, Cylinder Head in
the Service Manual 5411223
Do not remove the valve stem seals listed in the procedure as that is not required
for the replacement of the springs.
Note: Check the engine dataplate for correct valve lash (overhead set)
specifications.

Parts
Following parts will be provided for completion of the above step for each engine
that needs valve springs replaced:

Part Number

Quantity

Description

5303406

24

Valve Spring

3976371

6

Injector Seal

Additionally, following parts will be provided to repair facilities. However, these
parts should only be replaced if any damage is observed on the parts on the engine.

Part Number

Quantity Description

3977393

6

O-ring seal (Injector)

3940123

48

Valve Collet

3963379

1

Rocker Lever Housing
Gasket

4935974

2

Injector Fuel Supply
Tube

4935976

1

Injector Fuel Supply
Tube

4935981

1

Injector Fuel Supply
Tube

4935982

2

Injector Fuel Supply
Tube

2872288

6

Injector Fuel Supply
Connector

4954487

6

O-ring Seal (Injector
Fuel Supply
Connector)

3164329

1

Valve Spring
Compressor

Material Disposition
Valve springs removed as a result of this document must be returned to Cummins.
Please return the parts to:

Cummins Inc
Dock 72 RL407
500 Central Ave.
Columbus, IN 47201
Attn:

Note: Please include a copy of the claim paperwork and a material return tag with the
returned parts. Include the ESN number, and the claim number on the material return
tag. Please record the ESN number on the box.

Reimbursements
Refer to warranty memo M1906 and file a claim for the above repair work.