[ROVERNET - UK] more servo woes

[S Manwell]

Maybe you could test the operation of the valves by disconnecting the 
vacuum line and removing the plate and pipe from the side of the valve 
body, then having an assistant step on the brake.  If the engine is not 
running you wouldn't need to remove the vacuum line.  The valves may 
work a little differently without vacuum available on one side, but it 
seems like the control piston should still move when the brake pedal is 
pushed, and then the valves should move.  Maybe the control piston is 
not returning?

All that is easier said than done with the P5 carburettor in the way.

--Steve

peter king wrote:

> hi Steve.
>
> I did test the piston before tightening the mounting plate, piston  
> returned fine. The valves seemed to be fine, but I don't know how to  
> gauge if they are operating correctly.  I suppose I need to take the  
> servo apart again and see if anything is amiss.
>
>
>
> On Oct 22, 2006, at 7:44 PM, S Manwell wrote:
>
>> Peter,
>>
>> Did you test the big vacuum piston to see that it moves freely in  
>> the cylinder?  You should be able to push the piston in against the  
>> big spring and the spring force should be enough to return the  
>> piston when you release the pressure on it.
>>
>> The assembly of the valves on the side of the aluminum casting must  
>> be right too -- when you release the brake pedal, the control  piston 
>> in the smaller cylinder should return, causing the valve to  close 
>> off atmospheric pressure and apply equal vacuum to both sides  of the 
>> big piston allowing the big spring to return it.
>>
>> I can't think what the O-rings would be for...
>>
>> --Steve
>>
>> peter king wrote:
>>
>>> A frustrating day on the Rover farm today. I rebuilt the P5 servo   
>>> yesterday, and installed it today, but the brakes stuck on after   
>>> starting the car. I removed the servo and re-aligned the piston,   
>>> afraid that it was binding. After a second installation, the  
>>> brakes  still stick.
>>>
>>> The vacuum line valve is operating properly (one-way), no fluid   
>>> leaking past the seals into the vacuum chamber, so at least that   
>>> problem is fixed, but what other problem should I look for? There   
>>> were two small "O" rings in the rebuild kit which I could not  find  
>>> any use for. Might I have left something out?
>>>
>>> Any thoughts would be greatly appreciated.
>>>
>>> Thanks,
>>>
>>> Peter
>>>
>>>
>>>
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>>
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>
>
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