I have read many, what seems to be, conflicting procedures for bleeding the front brakes on a 1994 XJS.

- Some say to bleed the fro t brakes conventionally, I.e., leave key off, open bleeder valve, depress pedal, close bleeder valve, release pedal, continue until no air.

- Some say pump pedal to stage the accumulator, turn key on, open bleeder, depress pedal, close valve, release pedal, repeat until no air in fluid.

- Some say front brakes can be gravity bled, I.e., with key off and pedal up, just open bleeder val e until fluid flows w/o air.

-Some say, whichever process is used, start on the passenger side, others say start on the drivers side (assuming a LHD car)

i am going to replace my front rotors, calipers, and pads. Prior to removing the caliper, I plan on closing off the brake hose to the caliper, replace the caliper, then bleeding.

For those of you who have actually bled your front brakes, what process have you had success with?

NOTE: My XJS has the Teves system with the accumulator on the passenger side and the filler/master cylinder on the driver’s side (LHD).

thanx for any responses.

 

Hi rwolac

When you say 'Accumulator' does your Car have a 'Black Ball Accumulator' on top of the 'Brake Pump' and the Teves 'Master Cylinder Actuator' on the other side

Or have you got the Later 'Teves' set up with a 'Brake Booster' on one Side and the 'ABS' on the other Side which should resemble a 'Cylinder'

Always Bleed the Calipers, starting with the one that is Furthest away from the Master Cylinder Actuator or Brake Booster if you have one of those and then work your way to doing the one that is nearest

If you have a Photo of your Master Cylinder or Brake Booster Set up, then we could determine which Brake Bleeding Method might work best

 

I think he has this one same as me on the LHD cars It’s on the right hand side/ passenger side and master cylinder on the left side/ driver side. What system is this? thanks

 

rwolak,

There are many views and differing understanding of the version of the Teves system used between 1988 and 1995 (VIN 198334).

It's a very complex system which uses an hydraulic actuation unit rather than a traditional master cylinder and servo. The central body of the actuation unit has an Actuating Piston, a Boost Piston, a Master Piston in front of which is the Central Valve. It also has a Control Valve, a Main Valve and a Valve Block for control of the fluid flow under ABS conditions.

The reservoir that is mounted above the actuation unit also has a feed right across the car to the Pump and Accumulator which also combines a Combined Pressure Switch.

If you don't have the proper Workshop Manual (I'd really suggest you try and get hold of a DVD copy if you're going to try and run an XJS) then try and get hold of the documentation of the Teves system. It's very different from a traditional system!

Of the 3 options, you described above, I don't think you'll ever really succeed in trying to bleed wheel circuits just by opening the bleed nipple with no pressure in the system. The calipers are the lowest point of the system air won't go down on its own. So any air higher in the system will not be able to be purged through the caliper without pressure. I know that you're only changing the calipers with the brake pipe clamped, but you still run the risk of an air bubble higher than the bleed nipple.

Of the other two options, as mentioned in your other thread, I still believe that you should bleed the front brakes using the hydraulic pressure that is exerted on the Master Piston by the Boost Piston using the pressure driven by the Accumulator. This then assists the pedal pressure that you will then apply. And just to clarify, if you depress the pedal to discharge the accumulator, when you turn the key on, you'll just be repeatedly re-initiating the pump and accumulator anyway. And you then run the risk of burning out the pump if you're constantly making it re-energise the accumulator.

I know it's a complex issue and I'm sure you'll get differing opinions. Read as much as you can on the system. Also try phoning some really knowledgeable Jaguar independent garages for their opinions. (I can give you some numbers of some good ones in the UK, if you wish)

Good luck

Paul

 

Hi ptjs1 what would you consider the best manual I just bought this one I hope it’s a good one

 

Hi Sophi111707,

At the risk of disrupting rwolak's thread, it really depends on what XJS model you have. I'm guessing that the item you bought is a privately scanned and created CD / DVD? The picture is a pic of the front cover of one of the original paper Jaguar Workshop Manuals.

Jaguar did create a series of CD RoMs, then DVDs, of Parts & Workshop Manuals for the various models of XJS. Then as a result of political and legal issues, they stopped selling them a few years ago. you can still find them on ebay etc. They are classified under Jaguar part numbers JHMxxxx

To keep rwolak's thread on track, drop me a PM and tell me what model you've got and I'll tell you which one of those Jaguar CD RoMs was applicable to your car.

Cheers

Paul

 

Hi Sophi

You have the earlier Teves Mk1V with the 'Black Ball Accumulator' mounted on Top of the Brake Pump, LHD or RHD doesn't have much to do with it

The Chances are on a 1995 rwolac may have the Later 'Teves' System with the 'Brake Booster' and Separate ABS on the opposite side of the Car, which is a lot more forgiving and very seldom goes wrong

 

Here are what the brakes look like:

Drivers side




Passenger side

 

rwolak,

That's the 1988 to VIN 198334 system to which I referred.

Cheers

Paul

 

Looks like the Teves III system to me.

 

Yes, my VIN is 189216

 

So exactly what are you suggesting to use for bleeding the front brakes?

 

So exactly what process are you suggesting I use to bleed the front brakes?

 

rwolak,

My preference is to use the procedure I detailed in your other thread.

Good luck

Paul

 

Hi rwolac

Having seen your Photos, you have got the Older Teves Brake System in your Car with the 'Black Ball Accumulator' which is the same as the one on Sophi's Car

Although on my own Car, which is also a 1995, I've got the later Teves 'Brake Booster System' with a Separate ABS on the opposite side of the Car, so yours might just be Pre-Crossover

Though since you've got the Older System, there are a couple of things that you need to be extremely Careful of

(1) If you Bleed the Brakes with the Ignition on (like Paul ptjs) described in your other Thread, when the 'Brake Pump' regenerates after Pumping Brake Fluid through, do not allow the Brake Pump to run for more than 15 Seconds (again like Paul described) without a 2 minute rest in between or you could Burn out the Pump

'This can actually happen as I have burnt out a Brake Pump myself' so don't take the 15 Second thing with a 'pinch of salt'

(2) On no account lever the Brake Pads back, without the Bleed Nipple open as if you send Brake Fluid the Wrong way up the System, then this could do serious damage to the 'Master Cylinder Actuator'

If you do it the way that 'Paul' (ptjs) described then you should be ok although Bleeding the Brakes on an XJS can be a bit of a PIA at the best of times

 

thank you. Will follow your advice