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I'm having a problem bleeding the brakes on my 1994 XJS V-12. Here's a bit of history:
1. I've bled brakes on Jags many times, so I'm not a total newbie to the procedure in general.
2. This car new to me. I've just replaced all 4 rotors, pads on all 4 corners. Something is a little strange, though.... the rotors I removed were the original ones, as were the pads. The weird thing is the front pads were almost gone, but the back had 80% of their meat. I know the front wear faster, but this doesn't look right. I think the PO was driving it with non-functioning rear brakes and did not realize it.
3. Here is my problem now and why I think the rear brakes have not been working: I'm getting no brake fluid to either rear caliper. I've disconnected the lines all the way from the master cylinder to the back of the car and blown them out. They are clear.
4. Fluid will drip out of the brake lines when disconnected from both front calipers.
5. Fluid also will drip out of the MC from the center port (the one which supplies the rear calipers) when I disconnect the brake line from it.
6. The valve which mounts on the right side on the fender wall near the RH air cleaner is not clogged.
Not sure were to go from here. I'm open to ideas... I just think I'm missing something obvious here. Questions:
A) Is there a specific procedure to bleed brakes on this car (it does have ABS)?
B) Does the car need to be running to bleed brakes??
C) Is this a MC problem?
I'm having a problem bleeding the brakes on my 1994 XJS V-12. Here's a bit of history:
1. I've bled brakes on Jags many times, so I'm not a total newbie to the procedure in general.
2. This car new to me. I've just replaced all 4 rotors, pads on all 4 corners. Something is a little strange, though.... the rotors I removed were the original ones, as were the pads. The weird thing is the front pads were almost gone, but the back had 80% of their meat. I know the front wear faster, but this doesn't look right. I think the PO was driving it with non-functioning rear brakes and did not realize it.
3. Here is my problem now and why I think the rear brakes have not been working: I'm getting no brake fluid to either rear caliper. I've disconnected the lines all the way from the master cylinder to the back of the car and blown them out. They are clear.
4. Fluid will drip out of the brake lines when disconnected from both front calipers.
5. Fluid also will drip out of the MC from the center port (the one which supplies the rear calipers) when I disconnect the brake line from it.
6. The valve which mounts on the right side on the fender wall near the RH air cleaner is not clogged.
Not sure were to go from here. I'm open to ideas... I just think I'm missing something obvious here. Questions:
A) Is there a specific procedure to bleed brakes on this car (it does have ABS)?
B) Does the car need to be running to bleed brakes??
C) Is this a MC problem?
Thanks for any help!
l think your car has the later abs to my '89 so l cant advise you on specifics, but there is a very specific procedure for bleeding, particularly the rear brakes.
At least on the earlier system rears are bled with pump running.
l think your car has the later abs to my '89 so l cant advise you on specifics, but there is a very specific procedure for bleeding, particularly the rear brakes.
At least on the earlier system rears are bled with pump running.
Thanks; do you know where I can find that procedure?
Does your Master Cylinder Actuator look like this?
Master Cylinder Actuator
As fitted to my 1990 XJS 5.3 V12
If so this is what you do to get your Brakes working again.
To start with here are a couple of things to remember.
(1) Do NOT get any Brake Fluid on the Paintwork or it will Strip it in an instant.
(2) Do Not run the Engine
(3) Turning on the Ignition does NOT mean Start the Engine
(4) Do NOT let the Brake Pump run for more than 30 Seconds MAX
(5) When the ABS Light goes out and the Brake Light goes off (Listen for the Brake Pump) as it may still be running (so count that as part of the 30 Seconds MAX)
(6) If the Brake Pump runs for more than 30 Seconds, it could overheat and burn out so if 30 Seconds is not enough for some of this procedure.
Rest the Pump for 2 Minutes and then you can do another 30 Seconds.
Since you replaced the Rotors, it is highly likely that the Reservoir on the Master Cylinder Actuator may have run dry at some stage.
Which is why no Brake Fluid is finding its way to the Brake Lines.
Even though you have refilled the Reservoir and tried to Bleed the Brakes.
The reason being that you need to Bleed 'The Low Pressure Side of the System' BEFORE you Bleed the Brakes.
This is going to make a mess with Brake Fluid running all over the place in the Engine Compartment.
So cover all the Paintwork with Towels and have lots of rag ready and a Bucket of soapy water to wash down any accidental spills.
The reality is, it probably won't really be that bad but prepare for the worst just in case it happens!
The First job is De-pressurize the System: With the Ignition OFF pump the Brake Pedal 20 times.
Now for the most Traumatic Part of the Job, which will more than likely Shred Your Nerves!
But before we get to that DO NOT allow the Brake Reservoir to run dry, or you will have to start all over again, so have a mate on hand to keep it Topped Up.
Now have a look at this Photo:
Braided Pipe to Plastic Elbow requires a straight pull or you'll Break it!
On the end of that Braided Pipe on the Brake Pump is a Plastic Elbow held in place with that little Spring Clip by the Red dot of paint.
With the Ignition OFF pull the Spring Clip out.
Now Pack Rags all round the Brake Pump and make a sort of Fluid Chute out of Tin Foil, so hopefully any spilled Brake Fluid (and there WILL be some) will run down the Tin Foil Chute.
And into a Container placed under the Car.
Now for the really Scary Bit!
That Plastic Elbow needs to come out of the Brake Pump and it is held in by that Pin Clip which you just pulled out and also Straight Cut 'O' Ring.
This is a real Bar-Steward to get out! So be EXTREMELY CAREFUL OR YOU WILL BREAK IT!
First you need to very Minutely rock it to loosen it up, while at the same time giving it a Straight Pull or YOU WILL BREAK IT!
This will be a 'Nightmare' to get out, so take your time!
Also you need to do this while the whole thing is covered by a big piece of rag a bit like a Magician and if you have a Magic Wand, you could certainly do with it now.
You need the Rag just in case there is any pressure left in the System, which could have Brake Fluid shooting out everywhere. (which probably won't happen) although it could!
When you eventually manage to Pull out the Plastic Elbow, Brake Fluid will start to pour out of this Pipe (under gravity from the Reservoir)
DO NOT HAVE THE IGNITION SWITCHED ON WHILE DOING THIS!!!!!!!
Now let the Brake Fluid pour out of this Pipe (with the Elbow still on it) until the Brake Fluid runs Clear without any Air Bubbles.
This should only take about 5 Seconds but while the Brake Fluid is Still running out, put the Plastic Elbow back and then replace the Pin.
In other words you do the whole thing Live while the Fluids still running, so as you can imagine, its going to make a mess.
Don't drip any Brake Fluid on the Paintwork and pull any Brake Fluid Soaked Rags, out from under the Car and quickly wash down any spills inside the Engine Compartment.
Sometimes that Plastic Elbow comes out easy but more often than not its a PIA to pull out.
Rock the Pipe very gently as you try and pull the Plastic Elbow out.
Sometimes a Spanner can give you something to push on, as you try and twist it out.
Out at last!
Also note the Tin Foil Chute like they have at Water Parks only on a Slightly smaller scale!
Be very Careful that you do not break that Plastic Elbow!
That is the Hardest Part of the Job!
Part 2. on how to Bleed the Brakes will follow shortly (Time for a Cup of Tea!)
Orange,
Thanks for the insight to these brakes. Mine is not quite like yours, though. I don't have that little plastic pipe. On the opposite side of the car from the MC and reservoir, there is that pressurized thing that looks like a ball. I hope I can just turn on the ignition to activate the pump. I'll take your advice and not let it run more than 30 seconds!
That Black ball is the (Pressurized) Accumulator which sits on top of the Brake Pump the same as mine.
On my Car the Master Cylinder Actuator with the Plastic Reservoir is on one side of the Car, Drivers side on a (UK) Car.
While the Brake Pump (With the 'Black Ball' aka 'The Accumulator) is on the other side of the Car
Passenger Side on a (UK) Car.
The Master Cylinder Actuator with the reservoir on Top is on the Low Pressure Side, while the Brake Pump is on the High Pressure Side.
If there is any Air Trapped in the Pipe between the Low Pressure Side and the High Pressure Side, then you cannot Bleed the Brakes until that Air is out.
At least that's how it is on my own Car.
But if you have the Later Teves System, then you shouldn't have to Bleed the Low Pressure Side.
Although you will need the Brake Pump Running with the Ignition ON to Bleed the Rear Brakes (But Don't Start the Car)
The Brake Pump on my 1990 XJS V12
With the Pressurized Accumulator Ball
Orange,
Thanks for your help. I indeed have the system with the little pin and line on the low pressure side. I found it once I cleaned everything up. I did exactly as you said and everything is working well now. Bleeding this system is not difficult, once one knows how!
I'm in the exact same position. In my work and process of restoring the beast I replaced brakes, calipers, rear brakes and the three brake lines. Reservoir ran dry during. Brakes worked before and peddle responded and was firm but needed attention of course.
This is where I am.
I did the initial 20 pumps to de-pressurize system. Key off.
Removed and bled (I think) low pressure line. In my case hose came off of the elbow,,, so I just lowered the hose end and bled with hose lower then reservoir. Fluid flowed as you described. In reattaching I would raise hose end, still flowing, hold it to elbow, fluid slightly squirting out of little space intentionally left while assuring elbow fill, then press hose over elbow dealing and stopping flow. All seemed damn good there.
Then, rear brakes. Car key in on position, lights on in the dash. Here's where I think I went wrong.
You described PUMPING while the bleed nipple is open? Is that right? I did the 4 or 5 pumps and hold peddle down thing. Open bleeder nipple, peddle pressed down, release fluid, lots flowed, and then close nipple with peddle still down and repeat, 1 or 2 times. 4-5 pumps, hold, open nipple, fluid flow, close nipple, release peddle - repeat... Then on to other rear and same process.
Do I need to PUMP the peddle while nipple is open and then close while pumping? Let accumulator recover and repeat? I'm confused.
At the end, after doing the front, power off. Same pump, hold, bleed process - my peddle still falls all the way to the floor. I have front tire off the ground and with peddle depressed - can spin the tires/wheels by hand.
After all of this I pump peddle repeatedly, it will form up and almost feel normal. But after I stop and test again. Peddle is floppy and sloppy.
I did full process x2 so far.
Where am I going wrong? This is frying my brain.
p.s. can I bleed front brakes with key in the on position using the accumulator to refresh pressure in lines during bleeding or, is key in off position mandatory?
When you Bleed the Rear Brakes Turn the Key on (so you get lights on the dash) and can hear the Pump Running. (Don't Start the Car)
After 30 seconds the Pump should have built up pressure and the Pump should have Stopped Running and the ABS Light should be out.
If that hasn't happened, give the Pump a rest for 2 Minutes and then try again.
This time the Pump should have Stopped Running and the ABS Light should be out.
If not Rinse and Repeat until it does.
OK So now the Pump has Stopped Running and the ABS Light is out, leave the ignition Switched ON.
Then open the Bleed Nipple on the Rear Caliper furthest away from the Master Cylinder/Actuator.
On a (UK) Car that is (Passenger Side Rear)
You will also Notice that even with that Bleed Nipple Open, the Brake Pump hasn't cut in to recharge the System (YET!)
Now with that Bleed Nipple open, get a mate to Slowly Push the Brake Pedal down to the Floor and While he is holding it down, do up the Bleed Nipple.
That Bleed Nipple Should have a Tube on it, the end of which is submersed in a Jar of Brake Fluid (or use a store bought bleeding device) so that Air Cannot be sucked all the way back up the Tube)
You will also notice that as the Pedal is pushed down, the Brake Pump will then cut back in to recharge the System.
Rinse and Repeat that Process, as many times as it takes, to get ALL the Air out of THAT ONE Caliper, as if you do not do that, you will be wasting your time in doing the others.
Assuming that you've done that, then do the other Rear Caliper in Exactly the same way.
In the Event you can't get the Air Out, then you must have a leaky pipe somewhere, so no good doing the Front Brakes, until the Rear ones are Sorted.
Don't bother Pumping the Pedal, as until you've done the Front ones, the Brake Pedal will feel Soft.
Now onto the Front Brakes.
Same again, do the one Furthest away from the Master Cylinder/Actuator First.
On a (UK) Car: Passenger Side Front First.
Although you Don't Have to have the Ignition on for the Front ones, I do prefer to have it on to keep the Pump Recharged (But You Don't Have To) that's your Call.
Then do the Drivers Side Front.
Do them both one at a time, as many times as you need to, to get all the Air out.
Then you should be good to go with a Hard Pedal.
The only think that bothers me is you Didn't pull that Plastic Elbow out, as you know its very Fragile and could very easily Break.
You might just get away with that, we will have to see.
Although I'm tempted to say that I don't think so.
It will also probably take you a Full Five Liters of Brake Fluid.
Good Morning (here) OB! Thank you for the fast turn around. I luv this forum!
Ok. So - straight question. Considering I've done all of this brake work and had to build those two small brake lines on two new front calipers (which might be leaking). IF there was a leak - would the accumulator EVER stop running? I mean, if it was significant enough to bust any attempt at bleeding the brakes and getting a firm peddle - wouldn't it just run and run? That's not happening. And, if it were leaking, would I see a leak? Dripping coming from somewhere? I don't. I guess the question is - with a leak - will the accumulator just run in perpetuity with the key in the on position?
Later today I will see if I can find a kit so I can do this myself without an assistant AND so I am not just wasting brake fluid. I HAVE gone thru 3 quarts so far! aghrrrrr!
I will do fronts with key in ON positions as well and I will just keep it up til I get it right.
I really paused and thought about the necessity of the entire elbow being removed to bleed out the low pressure line. But all seemed complete with just the hose. Seemed like the same result must have been achieved.
I don't want to have to "take it some where" for this - with all I've done on my own.
No the Pump will not keep running if you've got a leaking Pipe, because its only Pressurizing the Pump and not the Actual Calipers themselves.
So once the Pumps been Pressurized it cuts out.
With only the very unlikely exception that there's a leak on the Pump (so rule that one right out)
You can also have a leaking Brake Pipe (The New ones you put in) that is so small you wouldn't even notice it at all.
And all you need is an Air Bubble about the size of a Raindrop and your Pedal is going to feel as Spongy as hell.
So only do ONE Caliper at a time and don't move on to the other Three until you've got that right.
That way you will know when you've got to the Bad one with the leak.
Another Big Clue that you might have a leak, is when you've got the Calipers all done up, then with the Ignition on, Pump the Brakes (fairly hard) then if
the Pump cuts in to make up the Space, it 'Could' (only 'could') be a Sign of an Air Leak.
Just to be on the Safe side, always put the Reservoir Cap back on, even if its only a couple of turns.
As for Bleeding the Brakes yourself, I came up with a method that actually works.
When bleeding the rear brakes on my '89 with ABS I did following:
1) jammed a piece of board between the brake pedal and the driver's seat to depress the brake pedal slightly.
2) turned on ignition (did not start engine). ABS pump did run for a while and stopped.
3) opened rear bleed nipple, first the further one. Brake fluid started flowing. Every now and then the brake pump ran for a short while
4) closed bleed nipple.
5) turned off ignition.
In my opinion there is no need to pump the brake pedal when bleeding the rear brakes. In the process you just need to pay attention that the pump does not overheat (running only 1/5 of the time max.) and watch out that the brake fluid reservoir does not run dry. With this method I pumped through over 0.5l of brake fluid through the rear bleed nipples.
I've been here at work all day thinking about options and approach. I think, with a plastic bottle and clear hose set up, hose curved over/above nipple, I am going to to do something similar to what you and OB are suggesting --- taking my time --- this evening after work. Seeing what part of this work I can let the pump actually do - and not waste a ton of fluid. Def not overworking or overheating the pump - but letting it do the work.
I really believe my problem may lie in the front two calipers. I will hook up clear hose, open bleeder, allow pump to do its thing, OR pump, OR both. Somethings gotta give.
Check for leaks as well - and stuff. I've been bleeding brakes since 17yo. Ill not be whipped like this, lol
Yes, some guys have Bench Bled the ABS (it only takes 1/2hr to take it out in one piece)
Having said that I've never needed to do that myself.
Jp72 could have come up with an even better idea and although I've never tried it myself, I will certainly give it a try at some time in the future (You can't learn less)
Although its looking like your front Calipers and the Pipes that you put on could be the problem.
Bleeding the Brakes on an XJS can be a bit of a Nightmare and a bit of a rite of passage that everyone with an XJS has to go through.
So if at first you don't succeed, don't beat yourself up, as its very often easier to Bleed an existing System, than to do it on one where New Calipers have been fitted.
If you hook up the Clear Hose thing, then you can very easily see all the Bubbles which will hopefully not return once you have bled them out.
Home made Bleeder.
All you need is a Bottle and a Piece of Tube
Make sure the end in the Bottle is submersed in Brake Fluid so it can't draw any Air Back.
The reason for the Long Tube is so I can position the Bottle where I am able to see it while sitting in the Car.
06-04-2017, 04:25 PM
Brakes question
