could anyone help me please im trying to remove the brake master cylinder to replace the seals.

im stuck and cant get it out, if anyone could help with photos would be great as im struggling to find any information to help me either photos or videos

its the model that DOESNT have the big servo on the back as ive found little bits on that model but it doesnt help me!

any help would be great

 

xjsjaguar,

If you don't have a servo and you've got a 1988-built car, then you've got the Teves ABS system.

That brake system doesn't have a typical master cylinder. It has a very complex actuation unit. I know a little about the ABS system and in 19 years of ownership, I've never seen an actuation unit that needed the seals changing to cure a brake problem (even if you could get the seals for it).

If you've got a brake problem, I'd suggest that you really don't take the actuation unit apart. I know only one person who has taken one of these units apart. I may be wrong but I'd suggest that the problem almost definitely lies elsewhere. If you can describe the symptoms you're experiencing, we may be able to offer some suggestions.

Cheers

Paul

 

Thankyou for the reply, im thinking its the seals because when i push the brake pedal in it goes to the floor without working and also i cant find no leaks or any loss of fluid?

im going to try and send a photo showing the unit that ive got.

 

This is a picture of the brake master cylinder that I’m trying to remove but if there any other advice you can give me for things to check to try remedy the problem that’s be great thanks. I’ll see what replies I get and try check other possibilities before removing this as it sounds like it’s not going to solve my problem how I thought it would. Thank you in advance. Stan

 

Hi Stan

No need to remove the Master Cylinder Actuator just yet (aka the whole thing including the Valve Block)

As it sounds like what you need to do is to Bleed the Brakes, that importantly also includes Bleeding the Low Pressure Side of the System (or you will be wasting your time) and this is nowhere near as Scary as I may have made it sound when I wrote this up some Years ago

Just Don't Spill any Brake Fluid on the Paintwork!

Having done that there are a couple of ways to Bleed the Actual Brakes themselves, where Paul (ptjs) will no doubt jump in an explain what to do, as this was a method that he pioneered himself as the XJS Brake System, is very, very, different to that found on Normal Cars and requires a Special Method of its own

And though I've tried Pauls method and it works very well, I much prefer to Gravity Bleed the Brakes on my own Car

So the advice to you would be to try Paul's method first and in the very unlikely event this doesn't work for you, then try Gravity Bleeding

Although whatever way you decide to go, Bleeding the Low Pressure side if the System is Absolutely ESSENTIAL!

Bleeding The Low Pressure Side of the Master Cylinder Actuator

Good Luck

Alex

 

Hi Stan,

As mentioned, your car doesn't have a separate master cylinder, the Teves ABS uses that complex Actuation Unit (the master cylinder is just a small chamber at the front end of that actuation unit).

Re your problem, a few thoughts that may help you diagnose the issue:

- Were the brakes working fine and the problem gradually appeared or did it just go like that one day?
- Is the brake fluid level fine?
- Are there any leaks of brake fluid visible anywhere, at either the Actuation unit, the pump (passenger side of car on the bulkhead, or at any of the four brake calipers?

To try and help diagnose further:

- Without the ignition on, press the brake pedal. What sort of pressure do you have?
- Press it again. What sort of pressure now?
- Press it 25 times. The pedal pressure should increase to very hard. Is that happening?
- Assuming the pedal has gone hard within 25 presses, release the pedal and turn on the ignition. The ABS pump should now start as you will have discharged the pressure in the accumulator with the 25 presses. Can you hear the pump running? How many seconds does it run before cutting out? It should be less than 45 seconds.

- Assuming the pump has run and then cut out, now press the brake pedal. What pressure does it have?
- IF the pedal does go right down, leave the ignition on and press the pedal quickly twice and hold the pressure on the second press. Does it go firmer on the second press?

Let us know how you get on.

Cheers

Paul

 

Hi Paul
thanks for responding the brake pedal just went to the floor there was no loss of fluid and no signs of leaks anywhere pumping the pedal with or without the engine running makes no difference each time it goes to the floor with no resistance local mechanic expects damaged seal due to lack of use less than 5000 miles in 21 years.
thanks
Stan

 

Hi Stan

Have a look at this: Repairing The Teves Master Cylinder Actuator

There are loads of Photos that may help, or at least give you an idea of whats inside the Valve Block

Although I would try Bleeding the Brakes First, as not only being the least expensive option but also one that could well solve the problem, as in the hands of a Garage you could easily find yourself on the end of a very large Bill, for something you could easily do yourself

Good Luck

Alex

 

Stan,

At the risk of sounding pedantic, if you go through the steps that I laid out previously, that is a really important step in helping to diagnose the problem. We need to know if:

- the accumulator has residual stored pressure. This is assessed by doing a specific 25-cycle discharge by pressing the brake pedal with ignition off

- whether the pump and accumulator are initiating running and then cutting out. This is assessed by following the steps above.

- Depending on the results above we will then ask you to undertake a "blink test" routine which diagnoses electrical circuit problems and dispmays the fault codes that may be the reason.

I would politely suggest that your local mechanical doesn't understand the Teves system. As mentioned you don't have a traditional master cinder with traditional seal structure.

If you just go through the analysis steps in the exact order suggested, we will get to the source of the problem eventually.

Cheers

Paul