FredS

The car has done about 43,000 miles and because i have owned it about 3 years I decided to change the brake fluid. The car has ABS and I have changed the fluid on previous Honda's with and without ABS without any problems.
The brake bleeding method I use is two handed. One person operates the brake while the other releases and closes the bleed nipple when the pedal is fully down also ensuring the fluid level does not fall below the minimum mark.
Since changing the fluid in this way i have have problems with a spongey brake pedal. i have bled the brakes three times and have got some air out of the system.
A mechanic bled the brakes by a slightly different method and got a small amount of air out. This made no improvement. He suggested air may be trapped in the ABS unit or the master cylinder could have flipped a seal by being operated in an unworn area it does not normally work in. He suggested a pressure bleed was the next and cheapest option. He could not carry this out as he did not have the specialist equipment but referred me to another garage who carried out the work.
The pressure bleed made no difference despite getting some air out. Two mechanics checked the brakes and diagnosed a faulty master cylinder suggesting the fluid was short circuiting around the master cylinder due to faulty seals as there was no fluid leaks.
With the engine not running the brake pedal is very hard.
When the engine is turned on the pedal sinks slowly to the floor.
There was nothing wrong with the brakes before I changed the fluid.
I have search this forum and several threads have suggested i should not have pressed the brake pedal right down to the floor for the reason given above.
A new master cylinder is £280 in the UK and on three days delivery (I understand it comes from Belgium?) I have not been able to source a replacement seal kit for the master cylinder in the UK.
Before I order the new master cylinder I would welcome any constructive comments.
Kind regards from across the pond.

Fred Surkitt

Before I order

ezone

Next time you want to change the fluid, I'd suggest use the "gravity bleed" method. As long as there was not already air trapped in the system, this works great as a lazy one-person method.

This line tells me Master Cylinder is bad.
Probably for the same reason you listed.
When the brake pedal went to the floor during the bleeding, you pushed the seals past their normal area of travel, and damaged a seal in doing so. (It happens more often that anyone wants to admit!)
Now the fluid is able to bypass from one section of the master into an unintended area.


I would obtain a replacement master cylinder, I would not attempt to replace only the seals. The average person might be able to replace the seals, but won't have equipment to re-hone the bore and remove the wear ridge that damaged the original seal.

This is a safety item. OTHER peoples' lives are at stake.


HTH

FredS

Thank you for your reply ezone.
It confirms what the other mechanics have diagnosed as the problem including not replacing the seals which are available separately in the UK.
I will now order a new master cylinder.
The Haynes manual (which advises pushing the brake pedal right down while bleeding) lists this as a straightforward job to do. It states basicaly disconnect the two brake lines and the two nuts holding the master cylinder to the servo. Is this correct ? Is there anything I should check out while doing this? Any advice, hints or tips about changing the master cylinder gratefully recevied.
As this will be a new master cylinder is it correct for me to assume I can bleed the brakes by fully depressing the brake pedal? If not please could you adise how to bleed the brakes? Is it likely to give problems getting the air out of the system particularly the ABS unit? Should I consider getting the system pressure bled?
I have never come across the gravity drip method of changing brake fluid please could you describe this?
Once again thank's for your help and advice.

Kind regards from across the pond.

Fred Surkitt.

ezone

Lunch break here, only have a second to type

Yes, in general.....but the new part must be prepped prior to installation first.
Bench bleed the new master cylinder. Instructions and a small kit are normally included with aftermarket units.
Factory leaves you to figure it out for yourself.

Clicky: http://bit.ly/10qwfZZ

If the lines are not tipped downward as they are disassembled, the master can be changed with only a minimum of air introduction/fluid loss from the brake lines. I don't know what the configuration of your car is though, so I can't tell you if this is feasible or not.

I try to bleed lines at the next available threaded assembly point. Many times that is the inlet lines at the ABS unit. If the pedal feels correct by then, I'm done.
Yes.
Do it the way you have been doing.
I've never had an issue with it on these cars.
Not unless you can't get it bled the normal way.Gravity bleeding will not get air out of the system. It is mainly good for fluid replacement only. It's slow too.

Clicky: http://bit.ly/14oGKgx
YW.

Ez1