It’s the secondary that is not connected to pedal box but on LHD side under heater box. It’s big and has the huge servo in it. I spoke to so many EType owners and very little problems with this and most running in originals. The three failures are new but I guess not Jaguar OEM ones.
They fitted unit number three and guess what??? That failed too so car still in the garage!
Hard luck. The master/reaction assembly and servo/secondary assemblies are usually new (and not necessarily unique to Es or even Jags) but three out of three duds is bad, assuming they are not being fitted by a gorilla with bad eyesight.
You would not believe the amount of “experts” now involved in resolving this … I’m the best be without car whilst this goes on! All being recorded and documented! Was think £200 per day for lack of use of my E…???
Dear Kevin,
I am not understanding this 100%. Do you mean that the second (slave) reservoir is filling up?
If there is fluid leaking out of the end of one of the assemblies, then the final seal on that unit is not sealing, e.g. to get fluid into the big servo body, it has probably come out of the end of the slave assembly. If it is puddling inside the footwell from behind the brake pedal, then the leak is out of the end of the master. If fluid is moving from one reservoir to the other, then the seal in the middle of the servo is not sealing. If it is coming out of the top through the unions, they they are not seated properly. If it is somehow coming out of the front of the master into the vacuum system, then the problem is at the front of the master.
If it is more than one of those, then there is more than one problem.
I don’t understand what a “masterservo” is - it’s either the master (the thing on the pedal box with a plastic plate on its end) or the servo (the big drum thing mounted onto the car body in the engine bay under the left hand engine frame).
kind regards
Marek
Thanks Marek - my car is right hand drive (UK). The master cylinder or the one attached to pedal is fine. The servo unit fitted under heater box is the one that has been changed 3 times. The reservoir above this has been over filling and the master reservoir has been emptying. There is no brake fluid inside the car and I believe the fluid went into servo then breather so white smoke from exhaust! Girling supply these replacement units from wherever (China??) through the main Jaguar parts. Companies. Watch this space!! Thank you Kevin
Thank you - that’s much clearer now.
You appear to have two leaks.
The servo is leaking inside the shuttle and fluid is moving from the high reservoir to the low reservoir through and past the seal half way down inside the bore of the slave unit where the two circuits meet. Assuming that you don’t have a PDWA that has a hole in the middle of it, then those are the only place where the two circuits meet. (The PDWA is a join between the two high pressure sides of the circuit with a piston between them. If the brake pressure drops dramatically on either circuit, then the piston is pushed to one side or the other and a warning light comes on. By this time, you’ll probably already have noticed that the brakes don’t work. It’s general failure mode is to simply seize up because it has never actuated.)
Either fault is only an internal leak inside the brake circuit so…
To get fluid pulled into the engine, you have another leak somewhere and the fluid may be sitting inside the drum of the servo or it may be inside the vacuum cannister before being pulled into the engine. If the rubber compound in all of the servo seals is the same or the bore of the servo is not smooth, then that is a prime candidate.
If you want, you can pull the vacuum cannister and turn it upside down to see whether it has brake fluid in there. You can also undo the band on the servo and see if any tips out. It’d be nice to do that on the bench and see what side of the seal it is if it is there.
kind regards
Marek
Or a quick check which I have done… leave the canister in place, remove the top fitting and insert a length of stiff wire with a light-colored insulation long enough to reach the bottom. Sort of like a dip stick.
Or if you have no regard for your health you can go to the hardware store buy small diameter (3/16 in) clear tube, a long piece 3 to 4 feet, feed it into the vacuum booster and suck on it like a straw and see the fluid rise in it. Do not suck it up the full length , hence the loooong tube.
But, um, I would never do that.
Kids don’t try this at home.
if there is fluid, shorten the tube for convenience and use a syringe to withdraw the fluid.
Hi Marek/Kevin.I am rather confused and concerned about this “project”. The terminology has also been somewhat confusing…its best to stick absolutely exactly as used in the Jaguar literature ! We have a brake system that has break fluid ( bf ) resevoirs ( upper and lower ), a master cylinder ( with a reaction valve attached to it ), and servo. When the master cylinder is old/worn it can leak bf from the upper resevoir , past the internal ( worn ) seals, and the lower resevoir fills up with fluid. This leaked fluid can also get into vacuum system and hence into the servo.The fix for this fault is to rebuild /replace the master cylinder, and empty the bf from the servo .This may involve the need for a complete servo dismantle and clean out.I am unclear why the servo has been replaced 3 times when its the master cylinder that is leaking. If I am completely off base then please advise.
Yup, completely off base, I’m afraid.
There are only two places where the brake fluid from one circuit meets the brake fluid from the other circuit.
#1 is in the middle of the servo shuttle and they are separated by a rubber seal. If that seal leaks, then low pressure brake fluid from one reservoir can travel to the other reservoir via gravity and capillary action.
#2 is a real long shot, but late s3 cars had a pressure difference warning activation device (“PDWA”) which is supposed to check whether one of the brake circuits has got a leak so bad that it has no pressure when the brakes are applied. This sits right between the two high pressure brake circuits and both brake circuits, when activated push on a piston joining between the two. If the brake pressure in the two circuits is hugely out of sync, then the piston is pushed towards one side and a warning light comes on. In theory, it would be possible for fluid to get from one side to the other, but that is pretty remote in my opinion as the piston is usually crudded up as it has probably never moved at all after all these years.
Any other leak past a seal or a union goes to the outside or into the vacuum system, whether it comes from the master or the slave/servo. A leak from the master as you suggest will have to then traverse from the right hand side all of the way through a vacuum pipe then into the servo or vacuum tank and then somehow rejoin the other (slave/servo) circuit and thus find its way up to the slave reservoir. That isn’t going to happen until the servo bellows are so full of brake fluid that the bottom half of the servo drum is full. If you’ve topped up that much brake fluid and not noticed that there just might be a fault, then no one on this list can help you.
A leak in the master but not into the vacuum circuit will simply have the effect of making the primary brake circuit have a head of fluid in much the same way as the clutch circuit has when at rest. If you look at the diagram in the manual, then you’ll see that the servo shuttle is spring loaded just as a clutch slave ultimately has a pressure plate to push against, so all that can happen is that the shuttle will settle further down the tube, attempting to activate both of the primary and the secondary brake circuits in the process. The access to the slave reservoir has to be cut off when the shuttle moves far enough, otherwise you’d have no secondary brake circuit at all and brake fluid in the primary circuit has to get past a seal in middle of the shuttle to reach the secondary brake circuit anyway.
kind regards
Marek
The master cylinder and reaction valve are good I’m told. It’s the servo cylinder that the garage keeps replacing. It’s still not fixed and I heard the suppliers are recalling servos ! As you can understand I am at my wits end on this having my car off the road for a relatively simple issue! The garage did change the reaction valve initially but not the master cylinder! Maybe others will join in this issue when theirs are recalled??
Thanks Marek bed time reading for me but will look at this in the morning with my manual . What you say is logical and makes sense so unsure why garage and OEM think it’s the one part?? Would make sense for me to change the old PDWA out as well as it’s the last thing to do. Really appreciate your help on this as it’s been frustrating as hell!!
Hi Marek, Thanks for your detailed explanation. I can’t say that i totally get yr explanation, and I will however take a careful look at the ROM and parts books. I have rebuilt 2 complete brake systems on both my 1970 SIIE and 1973 SIIIE so I have seen the internal details of these systems.I also know that you have considerable expertiece with these cars and you have shared this extensively on this forum, and always in in a very positive way…which why this forum works well.Regards, John H
When the bf ends up at the exhaust tips, what plausible bf related brake master(s) could have caused “white smoke” from the exhaust ? Coolant leak in head ? Freeze plug poped out ?
My new (Welsh) '66 FHC large servo brake unit is installed, and I plan on leaving the vac lines not connected; as if the master-servo (below) was leaking bf, I’ll observe evidence of bf leaking.
Many thanks, lots of useful info on JagLovers !
Patrick
'66 FHC
Appreciate all the inputs into this topic. The white smoke was small and not the same magnitude of electing the new Pope of Rome!! BTW I use Evans Waterless Coolant.
The hydraulic schematic is clear where the high and low pressure systems meet thus pointing to faulty seals in servo. Unit number 4 being fitted and tested today!! Fingers crossed!!!
Kevin, lets hope the fourth unit is the charm. If not, maybe the one line can be disconnects at the PDWA and plugged. Then see if fluid comes through the PDWA.
Dear John,
I’m only too happy to be wrong - I get to learn something rather than just do a thought experiment as to what a theoretical outcomes can be.
On my car, I have also had the brake fluid transfer problem and this is after the servo reservoir was moved up to the same height as the master reservoir during my fuel injection conversion. Since gravity would not be an issue and for me, the (mismatched) heights did not change at all when left standing in the garage (i.e. no leakage from either brake circuit and no equalisation of heights of liquid in the two reservoirs once unequal), I reasoned that a tiny amount of fluid was pumped between the circuits at the seal in the servo shuttle with every application of the brakes (or with every release of the brakes) in normal usage. The “fix” was to pack one reservoir with red grease and rebleed the system. It was instructive that the red colour first appeared in the wrong brake circuit’s caliper briefly and then all was good with further bleeding and the problem has never come back.
The OP has two separate leaks. They may or may not be related to each other.
To get brake fluid into the engine, it has to come through the vacuum system from one of two sources:- 1/ past the tiny rubber O ring seal on the end of the master where the little piston operates the reaction valve (“J” on the s3 brake diagram from 70.00.01 in the ROM); or, 2/ past the servo rubber seal at the drum end of the servo ("H to “A”) on the piston that comes through the drum into the slave cylinder.
To get fluid to build up the slave reservoir, it needs to get past the seal between “H” and “O”, or if by some mechanism failure in the PDWA, “N” links to “Q”, which must be connected to the slave through “O” if the brake has not been applied, but that’s a bit of a long shot imho, because pushing brake fluid straight into the slave reservoir from the primary brake circuit were they to be connected to it sounds easier than pushing the shuttle down the servo to seal it and thus have brakes that work, albeit both connected on one circuit.
kind regards
Marek
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Thanks again Guys for all the support and positive inputs for me! Still awaiting the garage to get back to me as the system under tests now…watch this space!!
Fingers crossed as this is number 4 and counting !!!