Brake servo problem - hissing noise?

[pouch]

I have a problem with the brakes. when I use the brakes there is a hissing noise and the brakes are less effective than before.
I guess this is a leak in the vacuum system. Any ideas where I am likely to find the problem?

Thanks,
martyn

[mdsalemi]

Martyn,

This should be relatively easy to isolate.

You'll need a helper, and maybe one of those mechanic's stethoscopes.

Start the car, raise the hood and have someone pump the brakes.

There is a vaccum line with a check valve in it that runs from the manifold on the R hand side of the engine to the brake booster on the left.

Start at the manifold and see if you can isolate the sound along the vacuum line.  If you are lucky, you will.  The line isn't too expensive to replace.

If the hissing is coming from the booster itself, that is a bit more to replace

However there are some places that claim to rebuild them, even though they are designed NOT to be rebuilt.  Personally, I'd replace it.  Don't fool with brakes.

[lurtch]

In 2006 Power Brake Exchange Inc. in San Jose Ca did mine for $192.68.

Rebuilding brake boosters is the largest part of their business ,  so they are the best choice for  a rebuild job. Had no problems with mine.

Regards, Larry in CA

[pouch]

Guys, that sound nice and easy to check, I will have a look next week when I am over with the car and let you know what it was.

If I need a new booster, lets hope I can find it in the UK !!

[pouch]

OK, I have done a few checks and read more threads.

The car is right hand drive, the brake booster makes a loud hissing / wooshing sound. It is loudest in the footwell by the brake pedal.
But on top of the brake booster, there is a rubber which covers an inspection hole? Beneath is a rubber belows and you can clearly hear the hissing from that location with the rubber sover removed.

There are no leaks in the vac pipes to the inlet manifold.

Also I get a rise in the revs when the brake pedal is pressed.

I guess this means a new or repaired brake booster.

Any ideas on where I can get this repaired in the UK
Or where can I get a new one? Are they available direct from mercedes?

Also, has anyone documented the change over, I don't have a workshop manual, but I guess I will be buying one at some point.

Cheers
Martyn

[pouch]

I found a company in the UK who can refurbish the brake booster / servo.

I'm not sure if they do all of the servo's, but can refurbish the later type.

They are called J&L Spares in Rochdale in the UK.
Anyone used them before cost is £250 + VAT / Better than the £620+VAT for a new one.

I will let you know what its like when it comes back, could be a usefull adress for the the supplier sheet?

[SteveK]

Martyn, I pulled my booster out to paint it a few weeks ago.   It's a real easy job.  2 nuts separate it from the master cylinder, 4 separate it from its support and then you have to remove the bolt that connects it to the peddle and the clamp that holds the vacuum line.   The only tricky part is carefully moving the master cylinder so you do not crimp a  brake line.  It takes less than 15 minutes to get in out and the same to put it back.

[gr8ppunkin]

I'm having a similar problem with my 280, and I looked at the autozone website.  They have remaned units for under $200, sounds like a reasonable way to go in my book.

[tel76]

Hello Pouch,
How did you go on with the repairer in rochdale?