THE INTERNATIONAL JAGUAR 'S'-TYPE REGISTER FORUM

It helps if you unbolt the servo shield from under the front wing to gain a bit more access, not an easy job!

And just for reference here is a photo of two servos, the one on the left is a commonly available replacement and the one on the right is the factory original. When my servo (after 56 years!) developed a vacuum leak (or so said my shop) they replaced it with the one on the left which as I understand it requires a bit of adjustment to the mounting and plumbing but it seems to work fine for the last 5 years. I guess it is possible to get all the bits to overhaul the original but not all do that now.

Possibly not as hard as a starter but similar problems of no space to work in and once you have your hands in the hole with a spanner you cannot see past your wrist to see where the head of the bolt is that the spanner is supposed to be turning. A lot of feel work and one handed especially with the brake pipes which is why it is best to leave the servo loose so these can be connected first, finger tight, before trying to get a spanner on them.
If you have a pressure washer or a strong hose give this area a good clean before and after as you might be dripping brake fluid on your paint work during the swap and brake fluid is like acid to your paint work. You might have a lot of brake fluid in the servo which will try and come out as you twist and turn it to come out of the engine bay so keep the pressure washer to hand during all phases to rinse off any rogue brake fluid.

Many thanks for your answer. I'll follow your advice and buy a new one.
Looks like another adventure. Oh well, it's a hobby ;) Hopefully it's going
to be a bit easier than fitting the new startermotor....

Found this in the mean time: https://kb.welshent.com/wp-content/uploads/2022/10/lr18230.pdf

I suppose I'll have to get all the motoroil renewed?

I would say it was the diaphragm in the brake servo that has got a hole in which allows the brake fluid to cross over to the dry side and is then sucked by the vacuum into the inlet manifold where it is sent to the cylinder and burnt as white smoke through the exhaust. I had the same thing on my MGB GT V8 as after a plume of smoke from the exhaust my brakes would fade away to nothing with no brake fluid in the reservoir.
A couple of cures.
The first is to repair the brake servo with a new diaphragm. All the parts are available from SNG Barrett but the cost and the fiddling around trying to repair it in my view is just not worth it when you can buy a new upgraded 4:25:1 servo for £200. https://www.sngbarratt.com/English/UK/parts/c8b441ee-0b70-4774-b351-75001120dd4b?fromCategory=BRAKING(1179)
This is a direct replacement for the original and you do not have to send your back or pay a surcharge when having yours rebuilt. I replaced mine for this type during my rebuild 11 years a go and have not had a problem since.

The servo is quite difficult to get to as it is in the engine bay on the right side inner wing below the distributor. To gain access there are several pipes and wires that need to be moved and taking the distributor out gives you room to get at things. Some might even remove the carburettors but I think this would give you more room but take a long time. The servo is held on to the inner wing by three or four bolts that hold not just the servo but also the servo shield which sticks out in to the wheel arch. From memory the bolts are only accessible from inside the engine bay and depending on how long they have been there could be rusted in due to the fact the threads are exposed to the elements inside the wing. To remove the servo I would expect it to take a couple of hours and the same to replace. A tip when refitting is to connect all the copper brake fluid pipes to the servo before you tighten up the bolts securing it to the inner wing. This allows you to jiggle the servo around to get the pipe threads started and helps not to cross thread the pipe ends.

Below is a photo of the servo in place on the inner wing obviously without the engine in place which makes it a lot easier to remove and replace.

[attachment=0]DSCF7608 (2).JPG[/attachment]

sorry, right hand drive

Hello everyone,

I need some help.

After replacing my starter motor, I now have another problem. My brake light didn't get out.
After fifteen years without any problems, it seems the gods have left me...

So I was looking for a leak in my brake system. (S-type 3.8 left hand drive) I had some white smoke, but at first I thought it was condense water.
Now because the white smoke got suddenly very dense, I think it's the brake servo assistance. (according to chatgtp :) )
I'm not a mechanic (my knowledge comes from youtube and this site), so I'd like some advice.

(I refilled the reservoir twice and it almost got empty everytime)

[u]First[/u]: where can I find the brake servo assistance and where is te vacuum tank (or can it still be something else).

[u]Second:[/u] Can I buy a repair kit for it (and is it doable), or should I renew the thing? (is there maybe a better solution than the original)

[u]And another question[/u]: out of curiosity: how can the brake fluid come into the motor?

Thanks for any advice.

Steve