This document discusses brake fluid, its purpose in vehicle braking systems, and recommendations for brake fluid maintenance. It begins by explaining what brake fluid is and its function of applying hydraulic pressure and protecting against corrosion. It then discusses factors that affect brake fluid quality like moisture absorption and depletion of corrosion inhibitors over time. The document recommends testing brake fluid for contaminating copper levels using test strips as copper indicates depleted corrosion protection. It concludes that flushing the brake fluid can be recommended if it is contaminated or beyond the original equipment manufacturer's service interval to maintain brake system integrity and performance.

1. What IS
BRAKE FLUID?

2. Polyethylene Glycol Based
(Not Oil Based)
PEG Products
Laxatives, Eye Drops, Skin Creams
Tooth Paste, Printer Ink Solvent
Spandex, Foam Cushions, Paint Ball Fill
All Start life as ethylene glycol--ANTIFREEZE

3. MAP was created to protect the interests of
 AutoRepair Industry
 Vehicle Owners
MAP’s mission is to insure consistency in
inspections of vehicles and communication of
that inspection to the customer.

4. Uniform Inspection and Communication Standards.
Shops needed uniformity in repair
recommendations
Customers needed more information
to make an educated decision

5. MAP BRAKE FLUID TASK COMMITTEE
WHY CHANGE BRAKE FLUID?
 Some say every 24,000 miles
 Others say every 36 months
 It’s Hygroscopic and absorbs moisture
 Technicians say replace if color is dark
 Its just a good thing to do (very unscientific)
WHAT’s RIGHT???

6. Information Sources
 National Institute of Standards and Technology NIST , Ricker,
R.E., Fink, J.L., Shapiro, L.C., and Schaefer, R.J., Preliminary Investigation Into
Corrosion in Anti-Lock Braking Systems
 SAE International Congress & Exposition, SAE Intl Jackson,
G.L., Levesque, R. and Wagner, F.T., Improved Methods for Testing the
Durability of Corrosion Protection in Brake Fluids.
 National Highway Traffic Safety Administration NHTSA
Person, G.H., Boyd, R., Demeter, K., Tests on Kelsey Hayes EBC4 Antilock
Brake Systems, Vehicle Research and Test Center
 The Institute of Mechanical Engineers Jacobson, M.A., Corrosion of
Motor Vehicles: Safety and Environmental Factors: The User’s View, Corrosion
of Motor Vehicles.
 FMVSS 116 Motor Vehicle Brake Fluids Code of Federal
Regulations , Title 49- Transportation, Chapter V-National Highway traffic
Safety Administration (DOT), Part 571-Federal Motor Vehicle Safety Standards,
B. Swidal Ed, Office of Federal Register, Washington, DC, 1995, 6. Anon., in
SAE Handbook, SAE International. NY, 1995

7. Brake Fluid DOT
Standard
FVMSS116
TESTS INCLUDE:
 Wet and Dry Boiling Point
 Corrosion
 Other tests
 Viscosities, evaporation,
effect on rubber

8. HygroScopic
Absorbs moisture
moIsture lowers the
boiling point

9. Wet & Dry Boiling Point
STANDARD 116
DRY BOIL WET BOIL
add 3.7% water
PEG DOT 3 401F 284F
PEG DOT 4 446F 311F
Silicone DOT 5 500F 356F
PEG DOT 5.1 518F 374F
DOT 4 & 5.1
Borate Esters are added to raise the boiling point.

10. Brake Fluid Boiling Point
• Very rare today (Private studies)
• OE Fluids have higher boiling points
• System design changes
SAE 2001-01-0947
Hoses with rubber inner layers did not resist
moisture as well as today’s hoses with EPDM
inner layers.

11. MAP as of 11/01/2003
 While moisture is an issue with brake fluids
The measurement of moisture that is detrimental to brake fluid
performance has not been found.
 In addition
No specification exists for an in-use brake fluid boiling point.
Therefore no recommendation for
replacement based on moisture
content can be made with confidence.

12. Corrosion Test

13. BRAKE FLUID ADDITIVE
 The only additive to base brake fluid is
Corrosion Inhibitor
DOT STANDARD 116 tests for corrosion.

14. COLOR
Is it Good or BAD?

15. Color Does NOT Prove
Contamination
 New fluid specification is colorless to amber.
 Dye from seals and hoses may cause the
brake fluid to turn a darker color.
 New vehicles have been found to have dark
fluid even before being driven.

16. O.E.M. Service Intervals
GM
FORD
CHRYSLER
Do NOT have SERVICE INTERVALS
Most Imports service interval is 24 to 36
months / 1000 miles

17. Corrosion Inhibitors
Buffering Amines
 Reduces the acid level
Filming Amines
 Protective film on metals
Note: Flush brake fluid when replacing calipers.

18. 2 Functions of BRAKE
FLUID
1. Apply hydraulic pressure to brake
components to slow the vehicle
2. Protect the Brake System from
CORROSION

19. Copper
 Is the first metal to corrode
 Direct relationship to depleted corrosion
inhibitors

20. Factors effecting Corrosion in
Brake Fluid
 Brake fluid chemical & thermal stability
 Brake system design, ABS
 Operator driving habits
 Outside temperature
 Road surface

21. Office of Defect Investigation (ODI)
National Institute of Standards and
Technology (NIST)
to study ABS MODULES

22. ABS and Corrosion
NIST STUDY
ABS systems have increased brake fluid mixing
results in the corrosion inhibitor concentration
decreasing faster.
ABS systems use close tolerance valves that must
operate quickly and more concisely than
conventional braking systems.
ABS systems are more susceptible to degradation
in performance due to corrosion or deposits.”

23. Braking Problem
NHTSA investigated sudden increased
pedal travel due to a leak in the modulator
dump valve. Their findings of the cause of
valve leakage was “very small particles of
pure copper present in the area of the
valve's dump seat and sealing surfaces.”

24. COPPER???
Where does it come from?

25. Examples of Internal Corrosion of
Brake Parts

26. Sludge Buildup in Low Spot of caliper

27. Rusting of Caliper Bore

28. Minor Corroded Piston

29. Severe Corroded Piston

30. Master Cylinder Examples

31. Primary Piston No Pressure Section

32. Primary Piston Pressure Section

33. Secondary Piston

34. Metering Valve

35. Proportioning Valve Insert

36. Height Valve Plunger

37. Import Height Valve Piston

38. Import Height Valve Piston 2

39. RWAL Inlet Filter

40. RWAL Isolation Valve Plunger

41. RWAL Reset Switch Cap

42. RWAL ABS Valve Examples

46. RWAL Reset Switch Piston

47. RWAL Dump Valve Plunger

48. RWAL Dump Valve Seat

49. 4WAL ABS Examples

50. 4WAL Isolation Valve

51. 4WAL Dump Valve

52. 4WAL Dump Valve 2

53. TEVES VI ABS Examples

54. TEVES VI Body Passages

55. TEVES VI Solenoid Valve

56. Copper Is….
 Early Warning for iron corrosion
 Indicator of lossed buffering capability
 Causes iron to corrode rapidly
SAE, Jackson, “After 30 months of service copper reached 200ppm”.
NIST, Ricker, “The hypothesis that the large surface area of copper in
the brake lines corrodes slowly during normal service resulting in the
accumulation of copper ions in the brake fluid that can be transported to
other parts of the braking system and cause corrosion of ferrous alloys,
once the corrosion inhibitors become depleted”.

57. Copper vs Iron
400
350
300
250
Copper
200
Iron
150
100
50
0
0 10 20 30 40 50 60 70 80 90 100 110
Months
TABLE 1. Copper and iron levels versus the age of brake fluid. Each pair of
iron/copper symbols represents a single vehicle

58. MAP Uniform Inspection &
Communication Standards
for Brake Fluid

59. Component : Brake Fluid
 At or beyond OEM service interval Suggest service
 Brake fluid type incorrect Require flushing
 Contaminated Require flushing
 Corrosion inhibitors depleted Require
flushing
 A copper content of 200 ppm or greater indicates
a depletion of corrosion inhibitors in the brake fluid
 Hydraulic component overhaul
or replacement Suggest flushing

60. BrakeStrip
Brake Fluid Corrosion Test Kit

61. BrakeStrip
 Is NOT a moisture test
 Measures contaminating metals COPPER
 Repeatable test
 Test results last over 30 days
 Easy to interpret results

62. PURPLE
Means there’s copper in the brake fluid

64. TEST Don’t Guess
 Gives the customer confidence
 Attach the BrakeStrip to the repair
order making an informed customer
 Increase brake fluid flush sales
 Use BrakeStrip on every inspection

65. Reasons to suggest a
Brake Flush:
 Beyond service interval (There are NO service
intervals for domestic OE!)
 Brake fluid type incorrect
 Contaminated with moisture (RARE and
hard to prove
 Contaminated with oil (Spongy rubber parts)
 Contaminated with corrosion (Copper)

66. Customer’s Brake Fluid Corrosion
Test Results

67. Customer’s Information

68. Brake Fluid Flushing
PRESSURE IS THE BEST METHOD
1 Apply brakes a few times to suspend contaminants in brake
fluid.
2 Remove old brake fluid and contaminants from reservoir.
3 Add new brake fluid to reservoir.
4 Hold down brake pedal 1 inch to allow fluid to escape from
master cylinder chamber.
5 Perform OE bleeding instruction including correct sequence.
6 Use at least 1 quart to ½ gallon of new brake fluid to pass
through system. (1 minute flow at each bleeder).

69. Testimonials
 “The test strips are great and most of our brake flushes
come from the test strips. The guys love to use them
and it makes them extra money.
 “The brake flush strips have increased flush system
sales 70% at our location over the previous year.”
 “Test strips work great and increase the trust factor in
the relationships with my customers.”

70. Brake Flush Profit
 Price of the Service $70.00
 Quart Brake Fluid -$5.00
 Technician’s labor -$15.00
 Profit $50.00

71. How many can you do in a Month?
10
20
30 Services?

72. Do What’s Right
 Make sure everyone in your shop is on
the same page.
 TEST for COPPER