S Type 2.7 Diesel brake servo.

[Keith1]

It appears that the brake servo has failed on my 2006 S Type.

I have spoken to lots of people (mainly on E-Bay) who are breaking S types, they tell me there are many different ones fitted over the years and they are snapped up very quickly because its a common fault.

 

I have looked at jag forums and nobody seems to mention it as a problem and it doesn't look that common.

Has anybody had any problems with servo's, any advice appreciated.

Thanks.

[Raistlin]

My servo needed replacing. With the diesel, it might be a servo or the vacuum pump causing problems.

 

Presumably you're getting a hard brake pedal with no servo assistance?

 

Servo / vacuum problems are common as far as I can tell, having Googled "S Type hard brake pedal", for example.

 

If you look under the insulation flap by the bulkhead on the driver's side of the engine bay with a torch you can easily read the servo part number.

 

It might be:-  6R83-2B195-BC, assuming that your VIN is very close to mine.

 

There are several types and they are not, sadly, interchangeable, but if you check the part number you will find second hand replacements readily available from specialist breakers like Essex Jag.

 

A new replacement from Jaguar costs £500 give or take a few pence.

 

Hope this helps :)

[pixal1]

Hi what is the mb or hg  pressures that you should expect from brake servo buster pump on 2.7 diesel jaguar 2004

[Raistlin]

Should be at least 18 mmHg.

[Herbie]

I have just had ANOTHER servo go on my 2006 diesel s-type. It was fitted 18 months ago and was a new part. Anyone know of a fault that eats servos, or are some of them not really fit for purpose?

[Raistlin]

There certainly seems to be anecdotal evidence that the brake servos are a weak link Herbie. That and the vacuum pump.

[Herbie]

So, I have found posts elsewhere indicating servo failure after replacing brake parts ... corroded brake pipes for instance. In my case the front hoses were replaced for a recent MOT.  Its not much fun driving one of these without brakes, but I'm getting better at it.

Can anyone see a reason for these servos failing after work on other parts of the system?

[DOWIE]

HELLO EVERYONE, IM NO ENGINEER, BUT I WONDERED IF ANYONE COULD HELP WITH THIS INTERMITTANT HARD BRAKE PROBLEM I HAVE. SOME SAY SERVO, SOME SAY VACUUM PUMP. ARE THERE ANY TESTS TO DETERMINE THIS ???

IT STARTED ABOUT A MONTH AGO AND ONLY APPEARS TO HAPPEN AT SLOW SPEEDS WHEN IVE PUMPED THE BRAKE SEVERAL TIMES. IF I ACCELERATE A LITTLE, I HAVE THE ASSISTANCE BACK UNTIL I PUMP IT SEVERAL TIMES AGAIN. I HAVE NO VISUAL LEAKS AND FLUID LEVELS ARE OK. SERVO OR VACUUM PUMP ? WHERE WOULD THESE PARTS BE POSITIONED IN MY ENGINE COMPARTMENT SO I CAN CHECK FOR ANY SPLIT PIPES ETC. THANKS FOR ANY HELP.

[Herbie]

Hello Joe,

My advice would be to get it to a garage soon ... the problem will get worse, and its not the easiest job to tackle yourself. Also the servo is likely to give out when you stamp on the brakes, i.e. when you need it most!  I have now discovered what was eating my servos; the vacuum was fine, so no-one suspected the vacuum pump. But it was leaking Oil past its seal into the servo. It then seems to take about 18 months for the servo seal to perish. So I had to replace both vacuum pump and servo (ouch). Moral of the story? When replacing a servo on a diesel LOOK INSIDE FOR Oil CONTAMINATION. Make sure your garage does. You can source servos second-hand (see earlier post) but I couldn't get a vacuum pump this way .....

 

Anyway, best of luck, and I hope its just the servo ....

[Raistlin]

Agree with Herbie 100%

 

When my old servo was was removed and inverted, Oil literally ran out of it.

 

The later part number, fitted, I believe from 2006 to end of manufacture, addressed this problem as far as I understand it.

[HIWEX]

Hi, I have the same problem.

I’d like to fix the problem once, if I were to fit a servo and vacuum pump from a later car, would they fit?

Cheers

Mike

[Herbie]

I imagine parts up to the end of manufacture will do fine ... I've had no further servo problems since replacing the vacuum pump. A few challenges elsewhere though ......

Herbie

[HIWEX]

Thanks Herbie, I’ll likely replace both and hope for the best.

Cheers

Mike

[Herbie]

Good plan!

While the bottom cover is off, check the steel water pipes near the front bumper; they sometimes rust through ...

And the plug which connects to the heater control; the copper cable corrodes if water has got there ....

Hopefully not in your case, but you now know places I've had to go.

Best of luck,

Herbie

[Skedgey]

I have a similar problem, where the grommet on the servo has deteriorated and split. Unable to get a grommet, I am obtaining a second user servo unit and master cylinder. I was also considering buying a new vacuum pump, having read that it allows Oil into the servo.

However, before I purchase a new vacuum pump, as mine still works, I have carried out some research, I have also taken apart my original vacuum pump (I replaced the original with a second user knee, about 18 months ago), the vacuum pump runs in Oil mist from the engine, which usually returns to the engine. The research I have done, would suggest that the non-return valve attached to the servo, is more likely the problem. This valve seals off the engine from the servo, if this valve stops working, then it is likely to let Oil into the servo, causing the problems which have been reported.

The non-return valve is installed in the hose between the brake servo and the intake manifold or the vacuum pump of the vehicle’s engine. When the engine is switched off, the valve closes to maintain vacuum in the brake servo, storing brake-assisting energy until the engine is restarted. The non-return valve also prevents fuel and oil fumes from entering the brake servo and damaging its internal rubber diaphragm.

[JOE-DOT-COM]

hi

usually find the servo fails because it has Oil inside it

if a non return valve is fitted, like on every other petrol version, it wont fail again

this only effects the diesels, not very often one fails on a petrol

the rubber gromment fail is similar, its usually oil  contamination that makes the rubber swell and split

cheers

Joe