No Brakes!

[extratime1983]

Hi All,

The car has been sitting in the drive for most of December and all of January. During my weekly check on the car last week, I noticed when I started it up, and pressed the brake, it sank all the way to the floor.
Had a good look round obvious things, damaged hoses, leaking callipers etc., but cannot find any leakage. Master cylinder is also still full of brake fluid.
Its worth noting that I had some brake pipes replaced last MOT.
Any ideas, master cylinder, abs??

[jagtech]

How old is the vehicle it matters because the braking system change with age might be a gas leakage if you have power brakes may be a master cylinder failure

[extratime1983]

Jagtech,

1994 4.0L (AJ16) Auto

[extratime1983]

The master cylinder has gone. £1600 + Vat from Jaguar. I am hereby passing my cap around - any donation welcome.

[ptjs1]

extratime1983,

If you're absolutely sure that it's the master cylinder that's gone, then you're right, it's big money for a new one. This is because up until 1995.25 Model Year, the master cylinder also incorporates the ABS actuator valve block (which is really the big money item).

After 1995.25, Jaguar utilised the revised Ford system which bolted the ABS actuator valves together with the ABS booster pump and kept the master cylinder on its own. The master cylinder for this yera has now been reduced to just £50! Unfortunately, that doesn't help you at the moment, I know. So you've got a couple of options:

Phone up Jaguar Classic Parts and see if they'll take an offer on the list price of £1622 + vat. I bet they've sold none at this price for some years. Make them a silly offer and just see what happens - you never know! I'd offer £250 to start and see if they are prepared to bargain. I bet that any of these actuators that thye've got will have been in stock for some time since the XJS parts stock was migrated over to the Classic Parts Division . Therefore, there is no purchase cost associated with them and sometimes they would rather shift stock and at least make some revenue on it. Be polite and you might be surprised!

The alternative is to source a used part. The good news is that it's the same unit fitted to all ABS XJSs up until 1995.25 MY so there should be plenty around. I would pay £100 for a known working one. Try ringing Graham Hallet at Grublogger.

Good luck, I hope you get it sorted.

Paul

[extratime1983]

Thanks Paul,

The original problem with the car having no brakes was leaking n/s front calliper. This has been rectified, but when the garage came to bleed the brakes, both back were ok, but fluid would not come through to the bleed nipples on the front, suggesting the master cylinder was drawing in air. The hoses have been checked. I had heard that pressing the brake pedal to the floor can damage the master cylinder seal (only something I heard once, nobody has actually qualified this for me). Anyway, guess who pressed the pedal to the floor

I contacted Graham shortly after receiving the bad news yesterday. This was after reading Gordon@1982’s woes in the Brake Master Cylinder discussion further down the forum. Graham has sorted me out with one for £100 + £20 Carriage. Its been said before, highly recommend Graham. Very helpful.

Willing to give this ago before I look into a new part.

[ptjs1]

extratime1983,

Glad you have been able to source a m/c from Graham. I hope that cures the prob.

I'm not sure how the garage bled the brakes or diagnosed a faulty m/c, but did they really understand the XJS system? On this type of ABS system, the front brakes are activated by fluid driven by the pressure exerted through the master cylinder. The rear brakes are activated by pressure driven by the booster pump, not the master cylinder per se. As the m/c piston moves forward it merely activates a scissor linkage which opens a valve allowing the electrically driven booster pump to send fluid to the rear brakes. It's quite a complicated system.

I would really recommend that you get a parts and service manual on CD from the JDHT for the car. They used to be only about £13 but I'm not sure of the exact price now. They have a really good section on the ABS brake system. You might well have a m/c problem as suspected but I'd hate to think you might be throwing good money away.

Good luck again

Paul

[extratime1983]

Update,

The brake m/s has been fitted, brakes have been bled and the car is due to get road tested this afternoon.

Heres hoping a nice trouble free summer of driving after this.

Thanks again for the replies.