Technical Intermittent brake servo assist.

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Technical Intermittent brake servo assist.

boguing

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I'm trying to diagnose this remotely, daughter is away with the car. She tells me that the pedal occasionally needs a lot more effort.

Fluid level is unchanged so I'm fairly sure that both circuits are leak free and probably working properly.

The car is running normally. In my mind that rules out a punctured diaphragm, and leaves me thinking that either something else has failed in the servo, or the vacuum pipe is suspect. On older cars with a laminated rubber/textile hose this would be the laminations breaking up and constricting under low pressure giving exactly these symptoms, but this is a rigid plastic pipe.

Anyone seen this - does the pipe ever suffer on Puntos?
 
I'm trying to diagnose this remotely, daughter is away with the car. She tells me that the pedal occasionally needs a lot more effort.

Fluid level is unchanged so I'm fairly sure that both circuits are leak free and probably working properly.

The car is running normally. In my mind that rules out a punctured diaphragm, and leaves me thinking that either something else has failed in the servo, or the vacuum pipe is suspect. On older cars with a laminated rubber/textile hose this would be the laminations breaking up and constricting under low pressure giving exactly these symptoms, but this is a rigid plastic pipe.

Anyone seen this - does the pipe ever suffer on Puntos?
It could be a slight loss of vacuum, where if she has to use the brakes a lot the vacuum is depleted. Obviously not being with her it is hard for you to check. With the engine off if she pumps the pedal several times to empty the vacuum reservoir, then holds her foot on the brake pedal and starts the engine she should feel the pedal pressure drop away as the servo does it's job of reducing the pedal effort. It should be quite noticable. As you say re rubber hoses , but the plastic ones can crack. On older Fords I have had the seal between the servo and the master cylinder fail and you could put playdough or similar there to prove the point, there was a small groove at the base.
I forgot to ask petrol or diesel as diesels have a vacuum pump on the engine which if it failed wouldn't effect the way the engine ran like petrol ones and also there are more small vacuum pipes prone to leaking in that circuit .
 
Thanks for that. (It is petrol, we don't have no stinkin' diesels in this family).

I spoke to her on Saturday pm once she'd got to where they were headed and it didn't do it again. I'll catch up with her over the next few days and see how it was on the return. Since it was just the once the first thing I want to eliminate is a rucked up carpet or stray puppy under the pedal. Then on to the tests you sensibly suggest. I'd wondered about a cracking pipe - it might only leak when flexed - or a decaying seal - twenty years and all the rubber and plastic has to come under suspicion. (I have a slightly newer Panda that got fed up with a lot of its hydraulic bits over about a month - at least they don't cost the earth). And yes, could be in the servo/mcyl too.

This remote diagnosis lark is taxing. I was recently assured that the wipers were going in opposite directions and clashing.... What had actually happened was that the right blade had slid out a bit and was hooking the left one sometimes. I'm not stumping for the screen with a nice arc carved into it. Then there was the boy's Clio. I helped him diagnose the sound of a failing wheel bearing, and so when I gave it a complete set of dampers and springs I put in two pairs of font wheel bearings. He now knows to drop the fecking back seat before deciding which end the noise is coming from.
 
Thanks for that. (It is petrol, we don't have no stinkin' diesels in this family).

I spoke to her on Saturday pm once she'd got to where they were headed and it didn't do it again. I'll catch up with her over the next few days and see how it was on the return. Since it was just the once the first thing I want to eliminate is a rucked up carpet or stray puppy under the pedal. Then on to the tests you sensibly suggest. I'd wondered about a cracking pipe - it might only leak when flexed - or a decaying seal - twenty years and all the rubber and plastic has to come under suspicion. (I have a slightly newer Panda that got fed up with a lot of its hydraulic bits over about a month - at least they don't cost the earth). And yes, could be in the servo/mcyl too.

This remote diagnosis lark is taxing. I was recently assured that the wipers were going in opposite directions and clashing.... What had actually happened was that the right blade had slid out a bit and was hooking the left one sometimes. I'm not stumping for the screen with a nice arc carved into it. Then there was the boy's Clio. I helped him diagnose the sound of a failing wheel bearing, and so when I gave it a complete set of dampers and springs I put in two pairs of font wheel bearings. He now knows to drop the fecking back seat before deciding which end the noise is coming from.
I do know where you are coming from , I have five children , I thought I had retired but I am still fixing their cars, one I have just got to petrol all the rest are diesel plus three of my own and one old petrol Citroen AX which is resting until I decide how deep I want to get involved in it. I got a panicky call from the new petrol driver saying the steering was jammed and she was late for work, when she had calmed down enough for me to understand her I was able to tell her to gently turn the ignition key at the same time rock the steering, she had parked on full lock and the steering lock had clicked in, problem solved!
 
I'm afraid it hasn't done it since.- I suspect rucked carpet.

If you have the same problem and solve it - would you mind putting the solution here?
Not saying so in your daughters case, but in the trade we had a saying "We have found the cause of your problem Sir, it's the nut loose behind the steering wheel" ;););)
 
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