My brakes feel a little spongy on initial application. If I release then immediately reapply the brakes it does feel firmer and more positive but after releasing the pedal again for a while the next time it's gone spongy again. I've bled all the calipers but it still feels a bit vague on initial pressing of the pedal. For context, my wife's 2014 XF S has far better and more consistent braking feel than my car.

I plugged in my SDD laptop last night and found a routine under Service Functions called "Brake Bleed" but there's zero explanation of what that involves or attempts to achieve. My iCarSoft device also has a Brake Bleed function within the ABS service functions. I've never had to bleed the ABS system on a car before so no idea what's involved, has anyone ever done this and can explain please? Alternatively, anyone else had the same sort of symptom and able to share their resolution?

 

Hey 8bit. Nothing I could find in you MY manual so I'm guessing the SDD function is for another make and model but others may know. Brake work appears pretty standard. I did see this. Hope it helps:

 

Thanks for that, I did see that in the workshop manual but haven't had a chance to try it. Ruled D1 and D4 out already though but might be interesting to try the other tests. I just plugged SDD in last night to see if there was anything potentially useful when selecting the symptoms of the brake pedal and saw the things I mentioned in my OP.

 

Had a similar issue, so I decided to bleed my brakes. I could see all the air bubbles coming out the whole time. Just kept coming and coming out lol.

Still felt like there was air in there, so I decided to have the dealer bleed them for $200. Well worth it. They seemed to get all the air out and the fluid in the reservoir still looks cleaner than ever.

And much firmer pedal now too.

 

As you are in Scotland you may like a UK widely available and low cost option for bleeding.

I use a Gunson Eezibleed kit with the addition of a non-return valve for the caliper tube end. It's the most basic, cheapest and easiest solution for pressure bleeding without needing an assistant to close the bleed screws. Very effective and makes a bleed or fluid flush a straightforward job. I bleed ABS with the engine running.

Plenty of more expensive pressure or vacuum equipment available if you prefer a larger volume supply reservoir or independent air pressure.

Graham

 

When bleeding, make certain you start with the caliper furthest from the reservoir and bleed at least a good pint (or more if needed) from all 4 calipers, sometimes just a little bleed accomplishes nothing. The routine does work on our cars but there's no need for it in your application.

 

Just curious. What does the SDD routine do exactly?

 

It usually operates the ABS pump to allow clean, bubble-free fluid to be circulated through the pump. Unless the pump is run, the valves remain closed and the new fluid simply bypasses the pump.
Richard

 

Thanks, I may do that, although looking at the staff at my local dealer, I think my car is older than most of them... :\

That's exactly what I have, albeit without the non-return valve. Not sure why you'd need that, if the pressure from the tyre is pushing the fluid out through the bleed valve then when you close the valve you won't get any air back in? What benefit/difference is there by bleeding with the engine running?

Thank you - I did exactly that first time round.

How does the ABS bleed work, is there a bleed valve on the ABS unit? Or do you bleed as normal through each caliper in turn with the ABS bleed routine doing something concurrently with the pump?

 

When fitting a new ABS unit, first the brake system is filled and bled via traditional methods which bypasses the ABS module, then the routine is run via SDD and the brake system is bled again one caliper at a time. The routine allows fluid to run through the ABS to remove air in the new ABS.

 

Usually the latter although some systems do have a bleed point on the ABS system. The diagnostic screen will probably walk you through the process.

Richard

 

Thanks gents. I haven't fitted a new ABS unit, I did replace the rear calipers recently but this poor pedal feel was present before that. I obviously bled the rears and the fronts as well (car was due a brake fluid change anyway) so was hoping that would cure it but I guess there's maybe a little air in there somewhere. Found the part number for the ABS pump and searched Google, found a listing here - https://www.ebay.com/itm/Anti-Lock-A...1831972?_ul=IL

Don't see anything on there that looks like a bleed point unless anyone knows better?

 

It doesn't appear to have a bleed point. If there is any air trapped in the ABS system, it won't affect normal braking so, as you say, it sounds as if you have air in the regular pipework somewhere. If there were any air trapped in the ABS system, you would not be aware of it until after the ABS operates when it might be pushed into the regular system.

The "traditional" method of flushing the ABS pump is to change the fluid in the regular system and then go out and stamp hard on the brakes a few times to activate the system.

Richard

 

It’s doesn’t, that’s what the SDD routine’s for but not likely the issue in your situation.