Brake pedal play

[grajack]

Recently had to change the brake servo on my Ford Focus 1.8Tdci 2006, due to it leaking vacuum. Ever since the brake pedal is lower than it was before.

Anybody have any idea's ,I've tried bleeding and even changed the master cylnder.

[Siye-ZS]

58 minutes ago, grajack said:

Recently had to change the brake servo on my Ford Focus 1.8Tdci 2006, due to it leaking vacuum. Ever since the brake pedal is lower than it was before.

Anybody have any idea's ,I've tried bleeding and even changed the master cylnder.

How are you going about bleeding the system? Maybe there is still air in there.

[grajack]

Bleeding by pumping pedal, doing furthest wheel i.e back left wheel first, the right wheel, then front left then right front. 20 pumps per wheel. 

[grajack]

Would the pressure system be any better, I have to admit I'm going towards air in the system, as first thing in the morning the brakes seem better untill after a few pumps.

[isetta]

does the car have ABS?  I think I heard that there is something special you have to do when bleeding the brakes on cars with abs

[TomsFocus]

Vacuum bleeding is great these days, but does require an air compressor.  I don't like pressure bleeding as it just seems to make a mess when I try it lol, and means you have to deflate your spare tyre to almost nothing, not ideal if you can't reinflate it at home.  I've got decent results from a 'one man' bleed kit with one way valve though.

The valves in the ABS pump are all open until activated so shouldn't really trap air during bleeding.  Not sure if you can trap air in the accumulator though, as that won't be open until needed, if you've got ForScan I think there is a service procedure on there for bleeding brakes where it can make sure everything gets opened in the ABS pump.  I haven't needed to do that on any ABS equipped car so far though.

[grajack]

Yes the car has ABS, was thinking of using the sealey brake and clutch bleeding system which replenishes the brake fluid as you go along, it has it's own pump, so wont have a problem with flat tyres, ( never heard of doing it that way anyway). I've checked thew ford ETS  service manual and there is no mention of doing anything special with ABS. Any help or advise would be usefull though.

[TomsFocus]

Sealey and Gunson both make cheap (under £20) pressure bleed kits, problem is they use the pressure from a spare tyre and the caps don't fit properly, so basically you end up with a flat tyre and brake fluid under pressure escaping from the res and running down the bulkhead.

Just googled to see the one with it's own pump, haven't seen those before but as long as the cap fits properly and the pressure can be kept fairly low it should work ok.

[Guzzilazz]

In the good old days when I looked after my own motorcycles, (knees and back preclude it now) I used to use a Mityvac hand pump attached to a reservoir via the bleed nipple, and you filled the system from the caliper up, so the air was pushed out upwards... Don't know whether it would be worth a go on a car...

[Micro]

I think the ABS service Bleed feature actually activates the ABS pump to bleed the fluid through. There are a few threads on this site related to it (Forscan ABS bleed)

[grajack]

Completely in the dark now..... So I need to bleed something else other than the brake cylinder and calipers. HELP !!!

[TomsFocus]

Basically there could be some air trapped in the ABS pump which is obviously between the master cylinder and the callipers.  The pump is electronically operated so needs some diagnostic software to operate it and make sure all valves in the pump get opened to remove any air - this air will then be pushed towards the caliper for you to bleed out as usual.  I guess ForScan has this feature but I haven't checked, as I put above, I've never needed to do that on ABS equipped cars so far, the main valves are all open as default.

 

I wouldn't bleed upwards, maybe fine for bikes (no bike experience here!) but it's likely to damage master cylinder seals pushing them backwards on a car MC.  Air doesn't 'rise' through brake fluid like it would through water so I don't see any benefit of bleeding upwards, the worst (old/boiled) fluid and most air should be at the calliper end anyway.