Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: dldubois on November 04, 2017, 14:38:16
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I've finally been putting a few miles on the 280sl now and finishing up the last of the projects I've got on the car (not that it will ever end). I notice when driving particularly on the highway that after driving awhile (30 mins or more) that I lose power braking.
Is it due to air in the system?
I replaced the master cylinder a couple of years back.
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Just from the perspective of an amateur who went through issues related to loss of booster aid:
1. When my brake booster said "enough" and went bad - I could hear the air hissing when I pressed the brake - it was easy to determine that it was the booster that collapsed.
2. After booster replacement I had:
- oring gasket between booster and main cylinder misfitted - I bought a new one fitted it correctly and it was ok for two years
- the hose-check valve from intake manifold to booster went bad, I bought a new one and replaced
These were the simple things. I am sure there may be more.
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That does not sound like a bad booster to me. brake fade after driving a half an hour leads me to believe you have a caliper or pad that is sticking. After a half hour of driving the caliper is getting hot enough to boil the brake fluid which makes the pedal spongy until the brakes cool. If I were diagnosing it I would drive it until the brakes fade and check the temperatures on the brakes on all 4 corners with a infrared thermometer. If and when you do find the problem make sure to flush and change the brake fluid.
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I agree with Pat. Also check for bad brake hoses also, causing the brakes to boil.