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My '85 XJ6 (American) has a leak at the brake master cylinder. The leak appears to be right where the plastic reservoir meets the metal cylinder. Is there a seal or seals there that can be replaced, or do I have to replace the whole master cylinder assembly? If there are seals are they a specific Jaguar part or just a generic O-ring? If they're O-rings does anyone know what size?
Not an O-ring. There is a multi lipped seal. It's leaking because it's most the MC is most likely rusting around the seal too. That all needs to be cleaned out properly. Best to get a re-manufactured master cylinder. 58$ + shipping at rockauto.com. Cant beat that for such a critical component.
Those rubber seals , due to age and engine heat , go hard and shrink causing oil to seep out.
" IF YOU HAVE NO OTHER ISSUES WITH YOUR BRAKES AND YOU DIDN'T WANT TO REPLACE THE B.M.CYLINDER " , then..... ,
Those seals " are " available after market separately , the part numbers marked in yellow ( below ) will suite most jag reservoirs .If you know how ,they can be replaced without removing the B.M.Cylinder.
Those part numbers are PBR International numbers and can be converted to most other brand numbers .
Good luck with that
Last edited by mastersid; Apr 17, 2016 at 11:21 PM.
Why is it...as far back as I can remember , every Jaguar engine compartment that I have peered into... has had its paint stripped off and rust has set in directly below the M/C ?
Why is this a chronic Jaguar problem and why has no one found a satisfactory solution to this wonderful piece of engineering? I had this problem years ago. So I rebuilt the M/C after completely refurbishing the M/C body and installed a brand new M/C rebuild kit ($ 60.00 for a handful of O-rings - rip off of the century) no joy.. leaked again shortly there after. So I ordered a brand new unit, master cylinder , reservoir and cap. Was so confident that I was on the right track, that I cleaned , sanded and repainted the mess under the M/C . Within a few weeks it was leaking again. If anyone has a direct GM style replacement encompassing the brake boost, M/C and the reservoir, I would go that far to rid my car of this Jag demon.
At times, it is just luck. when I got my car in 2001, there was evidence of a leaking master cylinder on the sing wall. but, there was what was clearly a new or rebuilt unit and bellows in place. leaks developed, but not there, the rear calipers... Now, that is fixed, rebuilds via Rock Auto.
System intact, so far, no fluid loss.
Yep, somewhere, there is a "different" master. One piece, reservoir and pistons. No weird plastic on top of CI!!! Just another joint of dissimilar material inviting a leak.
To get balance, one would need to find an application using disk brakes, front and rear with similar piston sizes. Or, introduce
a valve to adjust front to rear bias.
Not to mention pedal to cylinder stroke matching.
I might think of a method to replace the plastic reservoir.....
Metal on top, remote as in older Jags....
The innards are probably not an issue. All work about the same way.
Seals of a better rubber, Viton or soething...
Why is it...as far back as I can remember , every Jaguar engine compartment that I have peered into... has had its paint stripped off and rust has set in directly below the M/C ?
Why is this a chronic Jaguar problem and why has no one found a satisfactory solution to this wonderful piece of engineering? I had this problem years ago. So I rebuilt the M/C after completely refurbishing the M/C body and installed a brand new M/C rebuild kit ($ 60.00 for a handful of O-rings - rip off of the century) no joy.. leaked again shortly there after. So I ordered a brand new unit, master cylinder , reservoir and cap. Was so confident that I was on the right track, that I cleaned , sanded and repainted the mess under the M/C . Within a few weeks it was leaking again. If anyone has a direct GM style replacement encompassing the brake boost, M/C and the reservoir, I would go that far to rid my car of this Jag demon.
Same here...The rear seal leaks and strips the paint. I have tried many replacements. Stay tuned I will post details soon on a replacement MC but its certainly not a bolt in. The hood line prevents using many off the shelf MC's that bolt up but wont clear the hood.
Those rubber seals , due to age and engine heat , go hard and shrink causing oil to seep out.
" IF YOU HAVE NO OTHER ISSUES WITH YOUR BRAKES AND YOU DIDN'T WANT TO REPLACE THE B.M.CYLINDER " , then..... ,
Those seals " are " available after market separately , the part numbers marked in yellow ( below ) will suite most jag reservoirs .If you know how ,they can be replaced without removing the B.M.Cylinder.
Those part numbers are PBR International numbers and can be converted to most other brand numbers .
Good luck with that
Thats good info but as a practical matter where do you buy them?
I spent a few minutes Googling the parts numbers (with various keywords) and couldn't come up with anything....although a more diligent search might give results.
It appears that Autoparts Warehouse.com and Carparts.com might be USA distributors for (at least a few) PBR products. Perhaps they can help?
I "upgraded" to a S3 MC with reservoir... should have kept my S1 remote reservoir.
Then, after dealing with leaks, I found that the hood hits the rubber cap on top - I cut out a small section of the support brace that was hitting it... no
more problems.
Again , most " BRAKE SPECIALISTS" will carry them , they are a common failure on that type of master cyl design .
Those rubbers are normally about 3 to 5 dollars each .
If the part number can't be converted over , just give them a sample ,
Failing that , I would be more than happy to supply you some at no charge .
Cheers ,
Sid
What is a "Brake Specialist" I dont think we have those here in the USA. Few garages or retail stores sell repair parts like that. Too much liability, not enough profit. For better or worse, repair parts dont really fit in to the way Americans do business. Generally speaking items are sold as assemblies so they can be guaranteed to solve the problem. Just more efficient that way. Chances are if the seals on the top are perished then the seals inside are near perished too. That's reasonable... no?
Here in oooo-sa If we went into an Mieneke, Midas or JustBrakes looking for a seal...they would politely show you the door.
Last edited by icsamerica; Apr 18, 2016 at 05:55 PM.
Interestingly, and despite your insistence, I found this to not be the case, although it was quite a few years ago that I looked for any.
Besides the usual (and some unusual) parts supply houses I visited various brake repair shops ('specialists'?) to no avail. perhaps because removable reservoirs are a bit more unusual over here? I dunno. Or perhaps I just wasn't hitting the right places. I ended getting a 'reservoir kit' from a Jag specialist....about $40 as I recall.
Anyhow, thanks for the PBR parts numbers! I'll do some work on converting them ...hopefully...to something common/popular/readily available in the USA.
What do you do and were would you go if you needed a brake cylinder sleeved , or re-line or re-bond brake shoes , when they are no longer available from a dealership or an auto parts store ?
'85 XJ6 Master Cylinder Leak
