1. Ken Periman Problem solving, Brake Booster Fluid leak

2. Problem Statement
Brake Booster Fluid leak

3. Initial investigation
The issue: Team members are identifying brake fluid under the vehicle. Mostly identified at HADS Pit. The issue is being identified as emanating from this seal on the reservoir tank.
These are the seals and have been investigated by SQO and SQE as not having any damage or debris that would cause leakage from these seals.

4. Online investigation
Information has been provided by GA that on some occasions if a team member does not place the brake pedal on just right it could push the booster off the vehicle and onto the floor causing damage.
The booster, when placed onto the firewall is not secured until brake pedal install a few stations later
There has been a few occasions where SQE has noticed that the parts were stacked upon each other as shown in theses pictures. This is because of limited space at line and the team trying to remove empty carts and get full carts on line.
In both cases SQE has been working with T2 group leaders to reduce the potential of damage. All parts that fall off vehicles will be scrapped and team will refrain from stacking parts that may cause damage.
*All issues can be tracked to mostly one shift period at T2 install. 15 out of the last 17 issues were from one shift.
Repair has stated that the repair method previously was to unscrew the reservoir tank and reseat it to stop leaking. The seals on the reservoir have three ribs and are seated about 8 to 10 mm below into the valve body. The "reseating" only moves the seals about 2 to 3 mm at most. the "reseating" appears to do nothing for improvement as noted before there were no issues with the seals.

5. Supplier investigation
This Booster (Sedan) is built in Korea
This Booster (CUV) is built in the US
The booster that is built in the US (Local supplier) is similar to Korea with very little hands on operations. Almost all automated.
The booster that is built in Korea is shipped to the US (Local supplier) and then placed into a shipping container then shipped to OEM (Pass Through part).
In both cases there is a commonality of the valve body and reservoir and they are assembled in Korea. Local supplier is working with their supplier to collect data about their test methods of ensuring a good seal between parts.

6. Initial investigation
There has been some concern that this issue was the same issue we had a field claim for. THIS IS NOT TRUE. The field claim is for a seal being damaged in the valve body and allowing fluid to drain from the reservoir to the booster body. The current issue is a concern that the fluid may be leaking from the reservoir out on the valve body. this can be seen if leaking externally.

7. Investigation Results
There has been some findings by both repair and SQO where the repair method has been to wipe down the gasket area and no leak has been found.
It has been discovered that there is a probability that there was some fluid overspray from the brake fill and thus causing the fluid to flow down the reservoir to the rear seal and then drip from the vehicle where the pit team member noticed the fluid. And when the repair team member reviewed the vehicle they noticed brake fluid at the rear gasket and assumed that was where the fluid was coming from.
SQE will:
1. Request through QC to have the next two issues held for review by SQE and investigate the parts for possible issues not previously found or confirmation of overspray issue.
2. Follow up with Local supplier and their supplier to verify they are building good parts.
3. Continue to work with Assembly and repair to ensure good parts are provided and installed.
Common threads:
1. Almost all issues can be tracked to one shift
2. Reservoir tanks and valve bodies are assembled by the same supplier.
3. All boosters are not made in the same location
4. Issues fall across all boosters.
5. Previous method for repair was the unscrew the reservoir tank and "reseat" then no leak found.

8. Discovery:
Initial assumption from team was that the part was being supplied with either defective seals or damaged by Local supplier during install.
(No!) Local supplier only installed Sedan reservoir, Korea installs all others. Should have followed one type of booster.
Part issues were contained to one shift and with investigation found to one team member.
Further investigation found that the team member that was filling the reservoir was so aggressive that when he removed the filling device it was splashing fluid all over the booster and firewall. This was the final correlation – fluid all over the firewall on all vehicles identified with this issue.

9. Discovery cont:
If the investigation was not done correctly and was allowed to follow assumptions then the supplier would have faced defect part concerns and initiated an investigation that would have taken a lot of time and caused a waste of time without getting to the root cause.
Lesson – Do not go on assumptions and do a thorough investigation to find the root cause of issues. Many people have good intentions but often have limited information based on the area they are working in. As a quality specialist you go through all areas until a clear picture is developed and confirmed through data.