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Discussion Starter #1
I have a brake issue with my Junior and I would appreciate your ideas.
The brake pedal loose eficiency with the days and goes practically fully down after one week or something of use (not daily). When I press/depress quickly a couple of time the pedal goes up and firm, an indication that the servo is working properly.
Eight months ago, I put a new servo (not remanufactured) from Classic Alfa and also a new Benditalia pump. The system was totally purged and there are not any leak of brake fluid (the reservoir is full and keep the same level). After the purge the car brake very well for some days but after a week of use the pedal brake starting slowly to go down loosing eficiency.
The pump was take out of the car today and reviewed and tested. It works properly. Any evidence or leak and it keep the pressure well.
Tomorrow we will replace the brake hoses.
Could be the pump that is attached to the servo that is working improperly?.
Any idea?.
It is quite frustrating. Thanks.
 

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A pedal that goes down over time indicates a leak and/or air somewhere. You have looked at it joint (pipe, hose, booster, caliper, etc) to ensure each location is not leaking? Is it loosing fluid; that is, is the level of fluid in the reservoir getting lower?
Andrew
 

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Discussion Starter #3
Thanks Andrew. There are not brake fluid loose. The reservoir keep the high level. The problem is air somewhere but, where?. Could a caliper malfunction put air in the brake system?. Moreover, the servo is new. It is a mistery.
 

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I would think the only way a caliper could lose fluid would be a leak, which you could see.
The booster (floor pedals?) can leak fluid internally, getting sucked into the booster and going out the exhaust.
The master cylinder itself can have poor seals, enough to leak out, or just to lose some pressure and maybe show some fluid inside the bellows seal, but not leak onto the ground.
Single circuit brakes, not dual circuit?
Andrew
 

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Discussion Starter #5
So, is it impossible to have air going inside the system through the caliper?.
I confirm that There are not any lose of brake fluid in the calipers. I don't see any evidence of that and the level in the fluid reservoir is high.
The car has floor pedals, single circuit with Bendix servo (new). The master cylinder is clean outside (any evidence of leak) and we dismounted it from the car and was carefully inspected outside and inside and it works properly.
Other cause of the issue could be the brake swith. It is clean outside (no leak of fluid) but thinking now, not sure if air could enter in the system via this brake swith. Not sure about that.
 

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Probably not the calipers; I don't think there would be a problem there unless you saw a leak.
You can route around the booster (connect the two hydraulic pipes to it together temporarily with some connectors) to see if the problem goes away. You will have a firmer pedal because of no boost, but if the lost pedal problem goes away, you know your booster was the cause. You can also try swapping in a known good master cylinder to see if that's the problem.
Andrew
 

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Discussion Starter #7
I will go with this test and error analysis in order to see if the problem come from the booster. Let's see.

Could enter air in the system from the stop swith?.
 
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