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more servo help needed please?!!


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Evening gents,

Right I need some more help, but first here is some background,

I needed to change the servo as there was a small crack in the metal housing close to where the master cylinder bolts on, Even with this crack present the 130 still stopped on a sixpence with very little effort on the pedal.

I really couldn't afford a new genuine servo so I got one from the local independant parts dealer a allmakes servo. I fitted the servo last Friday and on completion I had no servo assistance whatsoever! i removed the servo and too it back, and picked up a new one tonight I have fitted this and its better than the last new one there is some servo assistance but not as good as the old servo I took off with the crack in it?!

I have taken the vacuum hose off and with the engine running there is lots of suction on the end of the pipe.

I am lost for ideas now, other than 1 last thing, I didn't get a new seal for between the servo and the master cylinder, Its an O ring I did clean it up and preserve it the best that I could, Could all this trouble be because there isn't a good enough seal between the servo and master cylinder?

Any ideas please folks? I will listen to all ideas/suggestions

many thanks

Matt

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To test the servo is operating, press the pedal and hold it, then start the engine. The pedal should sink approx an inch and then once again become hard. If the pedal doesn't do this then either the servo isn't working, the vaccuum pump isn't working, or there's a leak somewhere. You can also run the engine for a minute, switch it off, wait an hour, then disconnect the hose at the servo - there should be an audible hiss as stored vacuum is released. As long as the O-ring is in one piece it's unlikely to be causing a significant problem - you would have to have significant vaccuum loss for it to have such an effect and you would hear it hissing while the engine is running.

Les.

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To test the servo is operating, press the pedal and hold it, then start the engine. The pedal should sink approx an inch and then once again become hard. If the pedal doesn't do this then either the servo isn't working, the vaccuum pump isn't working, or there's a leak somewhere. You can also run the engine for a minute, switch it off, wait an hour, then disconnect the hose at the servo - there should be an audible hiss as stored vacuum is released. As long as the O-ring is in one piece it's unlikely to be causing a significant problem - you would have to have significant vaccuum loss for it to have such an effect and you would hear it hissing while the engine is running.

Les.

Hi Les the pedal doesn@t sink when starting the engine, there are no hissing noises, people are telling me to change the vacuum pump but at the end of the day my simple little head can@t work out why the old servo worked and a 2 new ones don't!! Is there a gauranteed way to test the pump before I shell out 100 quid?

Thanks

Matt

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I'd say you have a leak. My servo had a huge crack which mmgemini spotted and there was no hissing just poor brakes.

I replaced both servo and master and got an new Vac for good measure. Brakes are now superb.

Just in case.

Vaccum pump. Ebay user "kopdaz" otherwise know as Mailorder4x4. Cheapest I found. £85 inc delivery.

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I'd say you have a leak. My servo had a huge crack which mmgemini spotted and there was no hissing just poor brakes.

I replaced both servo and master and got an new Vac for good measure. Brakes are now superb.

Just in case.

Vaccum pump. Ebay user "kopdaz" otherwise know as Mailorder4x4. Cheapest I found. £85 inc delivery.

I had superb brakes with a cracked servo! thats what I can't understand! I can't find any leaks?

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so thats the side that has the vacuum so you should previously have been loosing pressure. I'm stumped.

Between the master and servo theres the O-ring and at the back theres a rubber gasket. One might be leaking. I'm presuming you did a full bleed if you drained the system and did it correctly? That would have a marked effect on performance and would create all sorts problems that might look like some of your symptoms.

All i can think of.

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so thats the side that has the vacuum so you should previously have been loosing pressure. I'm stumped.

Between the master and servo theres the O-ring and at the back theres a rubber gasket. One might be leaking. I'm presuming you did a full bleed if you drained the system and did it correctly? That would have a marked effect on performance and would create all sorts problems that might look like some of your symptoms.

All i can think of.

You would think so wouldn't you Neil! I haven't touched the Hydraulic side of the brakes, there was enough slack in the pipe work to let the master cylinder come away without disconnecting anything. As you say the crack in the old servo was on the vacuum side and there was no hissing or anything, but I could stop on a sixpence with little effort.

I am totally lost as what to try next!

thanks for your help

Matt

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Morning Guys,

Right there have been developments! This morning we eased the master cylinder off the servo and put a bead of instant gasket round the the flange and bolted it back up, Now when starting the engine with my foot on the brake the brake sinks about 10mm. also on application of the pedal there now appears to be a hissing noise from the inside of the pedal box, so I am wondering where this could be coming from? you can hear it more on the inside of the vehicle than the engine bay?

cheers

Matt

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Cheers neil!

All sorted now i removed the servo and put a jubilee clip around the bellow to seal it properley then used instant gasket between the servo and pedal box and hey presto i now have brakes like before! what a faff!

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