hi Guys, now I have done the following job twice before but in all honesty I dont recall it being much of an issue. Bleeding the brakes! Its an all new system and I have cracked various pipe nuts to encourage the reservoir to feed down into the master cylinder and the servo slave but no such luck. I have not started the engine yet and it may be that is the difference with the last time I did this a few years back. I am not too keen on using a pressurised bleeding system but will if needs must. Anyway, if anyone has a tip for getting the fluid down to the servo cylinder I would be grateful. Or else I will wait until the engine has been started in the hope that the servo helps the process. thanks
Am I to understand that you are trying to get a purely gravity feed?
yes indeed. I may have used a vacuum bleed kit last time, but I just cannot recall.
Depending on the state of the system when you started, you may not be able to move fluid solely by gravity over the high point of the line that connects the MC to the Slave. There are many discussions about bleeding in the J-L archives, which you can search on. Personally I have had the best results using the bicycle inner tube method, which puts a little positve pressure on both the MC and the slave.
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People will disagree, but I find it’s very easy if the engine is running so the booster is getting vacuum. Many struggle with getting this done just by pumping the brake.
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Thank you I will have a search on the topic. I am vaguely recalling that last time I used a simple vacuum device to help pull the fluid through. I think the item broke so I dispensed with it some time afterwards!
I suspect you are correct, it makes sense that the shuttles will be active with vacuum but could easily act as a stop if in the wrong location when static.
Andrew I had the same problem after rebuilding my from suspension and brake calipers while the engine was at the machine shop. I couldn’t get any fluid to move by pumping the brake pedal. I fitted an E-Z bleed kit with about 12 psi to the remote brake reservoir and got the front brakes to bleed.
Andy S2
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That is my most successful method also, but…the key to that quote is “little pressure”,…bike inner tubes can slip off…ask me how I know…what a mess…Jeff S. Atlanta, GA
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Thanks Guys. I have ordered a vacuum brake bleeder so will try that. I have a pressure vessel bleeder but I really dont want brake fluid to explode all over the engine bay. I will try to report back thanks again Andrew
Have you checked that the plastic pipe under the reservoir is not fully blocked?
Some reservoirs do not have the small metal pipe insert into the pipe above so your
fluid might be restricted by the plastic pipe.
Also, I had a bleeding problem exactly like yours. It turned out the problem was
that the new master cylinder was aftermarket and made overseas. I tried many ways to
bleed with no luck and then slight reservoir pressure worked.
I never figured out what was wrong in the master cylinder but I suspected bore diameter problems
I eventually replaced it when it started to leak a few months after install.
Dennis
69 OTS
Thanks Dennis, I have checked most of all your points, the reservoirs are the later SNG type with the steel insert in the neck. I honestly now think its the position of the various shuttles in the cylinder which is restricting flow. I have ordered a vacuum bleed tool so will report back after using that. thanks for the ideas. Andrew
I have tried vacuum bleed when I had the problem and it did not work.
Pressurizing the reservoir (about 1 or 2 psi) using and old cap and rigging it up, worked for me
Dennis
Ok that’s a bit depressing. A mate used vacuum and it did work however he had to bleed front brakes first or it would not bleed through. Interestingly having left both reservoirs topped up and awaiting my vacuum pot I noticed it has bled through a bit as I discovered a slight leak on one pipe nut.
Andrew,
If you don’t have the engine running (and maybe even if you do) you have to bleed the circuit fed by the master cylinder reservoir first. This is the circuit that is connected to the rearmost of the 3 ports on the top of the servo. It may be the front wheels or may be the back wheels depending on how your servo is connected - Jaguar changed this around during production.
Thanks David. Yes mine is a late series 1 and the rear of the three goes to the front brakes. ( I take you are not including in the three the main larger feed pipe from the master cylinder itself ) . The three being, front and rear feeds either side of the Servo cylinder reservoir. On a RHD car you have one reservoir on the bulkhead to feed the master and another on the engine frame above the servo to feed the servo cylinder
Correct…
Just by way of finishing this topic off my brakes are now bled and working just fine. So being the late 4.2 my front brakes feed from the rear outlet on the servo cylinder and the rear brakes feed from the front outlet on the servo cylinder. I filled both reservoirs and used a compressor fed vacuum bleed bottle to pull through fluid to the front pipes initially as I had been told you need to do this before the cylinder on the servo will operate internally to allow oil flow to the rear. Either way, it worked. I also cracked the pipe nuts on the servo cylinder to allow any air to bleed out . Left it over night and pretty much it was bled. I think gravity helped a lot. Thanks for all the help with this one. Andrew