Brake booster replacement

Hi All

I need to change my brake booster on my Nissan serena 2.0 SLX as the diaphragm is not functioning properly as a hissing noise is heard when I depress the brake pedal, I cannot see any damage or leaks on the hoses and was wondering if anyone has done this procedure before.

Do I simply undo the bolts holding the master cylinder to the servo without disrupting the brake lines, hence not needing to bleed the system and then disconnect clevis pin and pedal and then undo four bolts which support the booster from inside the vehicle.

Any information would be truly appreciated.

Thats basically the correct procedure, but I doubt if you will be able to remove the master cylinder without shifting at least some of the brake pipes.....give it a go though!
Tell me - is brake performance poor, i.e the brake pedal is harder than it should be?
John

Hi John

Thanks for the reply, the brakes work but feel a bit spongy, no hardness or difficulty depressing the pedal simply having to press the pedal further than normal to slow the vehicle down, but as I said hissing noise when pedal pushed in, so suspect a dodgy diaphragm.

A non Nissan new one retails around £230 quid, second hand around £30 - £50 but remembering it could be 18 to 20 years old?? so should I opt for a new being an important part of the braking system.

Regards

For sure, I wouldn't be too keen on fitting a replacement servo from a breakers - who knows how old it is The only servos I've replaced - a grand total of 3 - have been corroded through.
I would be happy fitting one from a motor factor though, if you can find one....prices vary considerably!

Here's a general test for a brake servo. Engine off, pump the brake pedal a good few times. The brake pedal should rise to the top and become completely hard. Keeping pedal pressure on, start the engine, and the vacuum formed should allow the pedal to drop to its normal position.

I'm not absolutely convinced that the spongy brakes are due to the servo issue, but if its hissing then this must be attended to first and see how things improve.

Good luck with the job - access is rarely pleasant and involves a hand stand in the footwell but yours may be easier! There's usually 2 nuts inside holding the servo, and one clevis pin connecting to the pedal.

John