Hello All!

I read posts here all the time but this is only the 2nd time I've asked for help, so please pardon any forum blunders I've made.

I replaced pads and rotors all around on my 1996 Vanden Plas, "Lady Jane". The work seemed to go well. I used nice Akebono pads and ATE rotors and I bled the system using a Motive Products power bleeder. (Great product.) I pushed 3 quarts of new Castrol DOT 4 fluid through the system just to get a good flush. I removed the power bleeder and tested the brakes. I had a super-soft pedal that sinks to the floor.

I flushed a second time with 3 more quarts, this time holding the bleed tube vertical at the bleeder (saw that in this forum) and also running a bead of sealing grease around the base of the bleeder screw. (I had been getting air sucked in at the threads of the bleeder itself, even when I only cracked the bleeder 1/8th turn, and even though I'm bleeding with pressure not vacuum. Go figure.) The last 10 minutes or so on each wheel were bubble-free. Result: Same sinking pedal. I'm almost sure I have air into the ABS system... here's why.

On (the last) 3 of the 4 wheels I was smart enough to merely crack the bleed screw a tad before pushing the caliper piston back, then close the bleeder. All good. But on the first wheel I was young(er) and (more) stupid and I disconnected the brake hose at the caliper and took the whole caliper over to the bench. No fluid seemed to be leaking from the end of the brake hose if I pointed the end of the hose upwards. I figured there was no pressure in the system. So I didn't plug the hose, just left it tucked up high and dry and went indoors for the night. (Wish I could go back in time and change that part!)

Next morning I came out to find a big puddle of brake fluid under the end of the open hose. This is the Right Front wheel (on an LHD car) and that line leads right back to the ABS unit which is only about 3 feet away. I'm sure the amount of fluid I saw was sufficient to drain the line and the ABS unit. I'm betting air in the ABS in the culprit here.

I understand the ABS unit is full of nooks and crannies that are hard to bleed. I searched this forum and didn't find a good DIY way to bleed an ABS unit. One answer seems to be to tow the car to a Jag dealer and let them use their computerized system to modulate the ABS pistons while bleeding. That's expensive and stings my do-it-yourselfer pride. But maybe that's the price for my dumb move in not plugging that brake line!

So... any ideas? Would it help to hold down the brake pedal while trying another bleed? Pump the brakes a million times at some point in the process? Have the ignition (or the engine) on while bleeding? Or is there a secret bleeder valve on the ABS unit itself? Or a way of treating a gland nut on the ABS like a bleeder and forcing air out? Any advice would be welcomed. My poor Lady Jane looks sad up there on those jack stands with all 4 paws in the air!

I'm pretty good with computers (for an old guy) and would even consider getting the Jaguar service program and the dongle required to connect OBD2 to my laptop (if it's in the "few hundred dollar" range). But I'm afraid that could open another can of worms and involve weeks of learning curve. Advice?

Thanks!

John



The ABS Unit

Janey on Jackstands

 

I don’t have a specific answer for your issue, but here’s a few things that may help your journey.

Firstly, there is no Jaguar computerised bleed process for the X300 so taking it to a dealer or buying Jaguar IDS isn’t really going to help.

Secondly, as with any other system on the car it’s important to diagnose where the fault is. I think you’re guessing or assuming what the problem is.

With soft brake pedal I would advise to work backwards from each wheel, eliminating components by removing lines and plugging them and seeing if it helps. So, for example, disconnect the FR caliper, plug the brake hose and test. Then move on.

Or you could jump straight to the ABS unit, pug all the outlets and see what happens. But don’t forget to also prove the Master Cylinder.

Using this approach, you should be able to prove (or not) that the ABS unit is the fault.

You can make plugs for the lines etc with a collection of brake pipe fittings and some short pieces of pipe that are sqeezed flat in a vice on one end. If you don’t have a pipe flaring tool most local car parts suppliers will make up pipes for you.

 

Hi John,

Is it possible that with all that fluid draining out by gravity, the fluid in the master cylinder dropped below the minimum level? If so, you may need to "bench bleed" the master cylinder, which you can do with it mounted in the car, but you will need a helper to work the brake pedal as in traditional two-person bleeding. Place a piece of 2X4 wood or some other object to prevent the brake pedal from sinking all the way to the floor, which can allow the piston in the M/C to hyperextend and displace seals. Have your helper slowly pump up the brake pedal a few times, then hold the pedal down while you loosen one of the output pipe fittings on the master cylinder until fluid squirts out. Retighten the fitting and have the helper let the pedal up. Repeat several times. Then do the same on the other output line on the master cylinder, topping up the fluid as necessary.

You can do a similar process at the four ABS modulator output lines.

One "old school" tip if you can't find any other cause of your soft pedal and don't have a scan tool that can activate/exercise the ABS modulator is to take the car to a vacant parking lot or road and perform several "emergency" stops to force the ABS to kick in. This will cause the solenoid valves in the modulator to operate and potentially force any air out of the modulator and into the brake lines toward the calipers. Then repeat your bleeding at all four calipers. You should not need more than 1 additional quart of fluid to bleed the system unless your problem is at the master cylinder.

Cheers,

Don

 

I’ve destroyed the rear flexi hose on a curb and used the brake pedal to push a piston out when rebuilding a caliper and needed minimal bleeding effort in both cases. You may just need an assistant to make your job easier

 

Thanks, Brendan! Good to know the dealer and the IDS are off the table as options.
I'll proceed along the lines you suggested. I just need to get some plugs put together.
I guess the logic would be that if the pedal still sinks with each of the calipers plugged, then the air is either in the master cylinder or the ABS.
Then maybe undo the 2 lines coming out of the MC, plug the ports, and test again. If pedal is firm, the MC is good and the air is in the ABS. If pedal still sinks, the problem is the MC. (Maybe got air in the MC if fluid level sank too low at some point.) Sound right?
John

 

Thanks, Don. Yep, sound like I'll be doing some testing to narrow down the air location. I'll either bleed the MC or test it first by blocking the outlets.
I just need to get together some plugs and such.
I love the "old school" tip! I'll give that a try... assuming the brakes are good enough to lock up the wheels. With the new power bleeder, bleeding is no sweat -- so long as the air is in a place where it CAN be bled out.

 

I disagree John, your Lady Jane is still gorgeous, even without wheels! How can that be? Best in Class in the "Car with no wheels" category.

I do agree with the advice of our wise members above, they are some of the best in the "business".

 

Yep, you've got it.

 

Agree with all of the above, and a couple of thoughts spring to mind.
When you were pressure bleeding the system, did you at any point push the brake pedal while a bleed screw was open? The reason I ask is that it is possible to "flip" the edges of the master cylinder seal, which can cause a problem. The test suggested above will identify if this is the case.
I am not familiar with the specific pressure bleeder you are using, but generally pressure bleeders work better at low / modest pressures. Mine connects to a tyre for pressure, and I usually deflate it to around 20 psi first. Steady flow, with little risk of the fluid becoming aerated as it is pushed into the system.
There is an order for bleeding the wheels, basically longest pipe runs first. It may be possible to create some form of airlock if the sequence isnt followed.
Should you feel the need to trigger the ABS pump, a gravel driveway is a slightly gentler way to provoke the ABS!
You seem to have used a prodigious quantity of brake fluid. Were you getting equal flow rates at each wheel?

As the guys have indicated above, there are no special tools needed beyond your pressure bleeder, and a slow and steady approach should produce the required result.

 

I was able to perform the pump motor test, and computerized brake bleeding using my Snap-On scanner configured for 1995 Lincoln Town Car. I have also used the same procedure on a 1996. If you follow my post X300 ABS Diagnostic and Bleeding

 

Bleeding the ABS requires you to enable the automated bleeding process. Find a scanner that can do ABS procedures for a 1995 lincoln Town Car, configure the scanner before plugging it in and it should allow you to do pump motor test, ABS bleed and some codes

 

Darren,
I was interested to read your post, as I have found myself having similar thoughts about backtracking through the Ford DNA / gene pool on various issues (Throttle position sensor and Airbag control module to name but two), but I had not had any need to do so in connection with the brakes.
Like Brendan, I was of the view that there is no automated brake bleed proceedure, and having read your linked post as you suggest I am not sure that I can follow what you are saying. I can easily accept that you can access ABS diagnostic codes, but I dont understand how there can be an automated bleed proceedure which does not require manual opening and closing of the bleed screws. Have you simply not mentioned that part, or am I missing something?

 

Sorry about the confusion. In order to bleed the ABS control assembly requires you to cycle the valves and pump while holding the brake pedal down using your foot. When you access the ABS module for automated bleed, the ABS pump will turn on and cycle fluid through the valves and pressure chambers in the hydraulic assembly. This removes entrapped air and allows you to move on to manual bleeding. As the automated bleed process takes place you will feel the brake pedal move up and down as the module switches from dump (pedal drops) to build (pedal rises) whilst the ABS pump is supplying fluid movement. During the automated bleed process the bleeders must be closed.

I might mention that some times a person might consider using DOT 5 brake fluid, this is an ABSOLUTE NO! DOT 5 has one fatal flaw, when used in an ABS system that uses a pump, it whips up into a froth. And this leads to the brakes becoming spongy and in some cases totally inoperative.

 

Thanks Darren, interesting stuff.

In the UK/Europe we may be more limited I think. My current general purpose diagnostic system is Delphi. It doesn't even list Lincoln as a brand, and only goes back to 2002 for Jaguar.

But good that there are some alternatives out there. I have an old Ford IDS system and I'll have a look if there are some options in there.

 

I am glad you called me on that point, I neglected to consider the global nature of the forum. Thankfully the basics of the ABS system remained the same in as far as enabling certain generic functions. My experiences with ABS (and many other things automotive) started back in the late 70's. I recall an ABS class I took some time in the late 80's or early 90's about the latest TEVES systems used in GM, Ford and others that there were some work arounds. At that time, the only good diagnostic systems other than dealer level were the manufacturer diagnostic/engineering bench systems which were quite expensive, well beyond the means of even dealer purchasing. It was around this time that several aftermarket diagnostic device manufacturers came up with their own systems, some of which were dedicated to one purpose.

I still have several of the old snap-on red bricks (MT2500) that used cartridges. I'll have to dig them out and see if they are capable of doing some procedures. If they can, they are quite affordable used with some going well under $500 (USD) I recall that the early MT2500's had a separate ABS cartridge that specifically targeted the TEVES systems.I am about to leave and drive up to Champaign Illinois (7.5 hr drive) and will dig the old red bricks out and bring them back to Arkansas for testing.

 

This may or may not be useful, but I was in a similar situation this summer with my 1966 S Type. I had a bad master cylinder and absolutely could not get the system bleed after replacing the master. Due to the position of the master cylinder, it's impossible to bench bleed and I tried pressure bleeding and it would not clear the air.

I did some critical thinking, and I remembered when I toured the Jaguar factory and saw the XJ's being built that there are no guys at the wheels trying to get fluid through, all the fluid supply hoses (brake/coolant/refrigerant) are hooked up to a machine by one operator and all the fluids are put into the car automatically. The brake system is put under vacuum and then the brake fluid is put into a vacuum, so there is no air to bleed.

So I hooked up my AC vacuum pump and jury rigged a rats nest of 5 hoses and 6 fittings to go between my AC manifold and the master cylinder reservoir and I was able to apply vacuum to the reservoir. Once I turned on the vacuum pump and cracked open the gauge valve, the brake fluid in the reservoir looked like it was boiling, there was so much air coming out. After maybe 30 seconds of applying the vacuum, there was no more bubbles coming out, so I shut off the vacuum, topped up the fluid and after seating the pistons I had a hard pedal. If you are still having trouble bleeding, perhaps try vacuum out the air, rather than pushing it out.

 

Thanks for the interesting idea! But for now, at least, I think my problem is solved.

I followed the advice of 2 kind folks here and went out and activated the ABS by stomping on the brakes. I took advantage of the first serious rain we had in California to find a nice wet road, and it was no problem to get the ABS to kick in.

After 6 or 8 rounds of that (with cooling time in between), I bled the brakes again.

Now the pedal feels firm. And with the new pads and rotors, the brakes are quiet and smooth.

So all is well! Thanks to all who replied!

 

John,
That is great news, happy motoring!
Trying to pull the elements of this tread together for posterity, it seems that we have established the following:
1) Brakes can be pressure bled or vacuum bled, in addition to what I would call "manually " bled by pumping the pedal with an assistant at the wheels.
2) Routine bleeding of the system, say for a biennial change of brake fluid, can be achieved without the need to activate the ABS system.
3) Replacement of components "downstream" of the ABS unit can be undertaken and the system bled without the need to activate the ABS system.
4) Replacement of the master cylinder or ABS unit, or air entering the reservoir during bleeding can result in a need to cycle the ABS pump, effectively to prime it.
5) There is a procedure for cycling the ABS pump remotely, if you can find a scanner which can access it, or it can be achieved by the more traditional means of activating the ABS.

Having followed the thread with interest, there is only one point which seems ambiguous. Darren suggests that the bleeding can be achieved automatically by cycling the ABS, whereas John says that the system had to be bled again afterwards. My own tuppence worth would be that the system would need to be bled after cycling the ABS. Cycling the ABS would push the air out of the pump, but it has to go somewhere, ie the pipework, necessitating further bleeding to remove it. Thoughts guys?

 

Allow me to clarify the misunderstanding.I am going to be referencing a generic type ABS system, so some references may not apply to a specific car. ABS in normal driving is a side system (branch) of a normal basic brake system. In normal driving The basic system handles all the braking requirements. In order to maintain a balanced braking system where all wheels should skid at the same time the auto builder designs the size of the caliper/wheel cylinders and the contact area of the brake frictions to achieve this. However, due to varying loads I.E turning, passengers, cargo, road conditions, etc. that balance point moves about. In order to maintain the shortest stopping distance and control is where ABS comes into play. Now depending on how the ABS system is designed and integrated into a vehicle, once you press the brake pedal it forces brake fluid through channels in the ABS module.

#1 -During this time through a series of solenoid and check valves, that fluid may follow a path literally straight through to the piping out to each individual wheel.

#2 - It may partially fill a reservoir in the ABS module (this could be a cylinder backed with a spring, or a chamber with a bladder surrounded by high pressure gas like nitrogen, etc)

Getting back to those solenoid and check valves, depending on the system, those may be open or closed depending on whether the ignition is switched on/off and whether or not the brake pedal is pressed. Due to the many passages and locations of valves etc, air may become trapped in a way that normal bleeding cannot remove. So in the ABS programing there may bee a brake bleeding procedure that requires activation to move that air out of those places and into a position where through the normal bleed you can finish removing it. If you have ever used one of those siphon hoses with the check ball in the end that by rapidly pushing the hose up and down in a liquid causes the fluid to rise and displace the air then you'll get the idea. So when performing the "automated bleeding procedure" you are moving the trapped air out of the nooks and crannies into a place where it can be easily removed.

A good example of difficult bleeding is on some manufacturers hydraulic clutch systems. A perfect example was the late70's to early 80's Mazda RX7 (LHD) Where short of having the factory/dealer bleeding system, you had to assemble the hydraulic system on the bench, hold the slave cylinder above the master and bleed it then attempt to reinstall the assembled system back in the car.

Getting back to the automated bleeding procedure, there are valid reasons for doing it instead of the work around of just doing several induced ABS stops. Visualize the inside of the hydraulic system as that of a diesel (petrol ignition) combustion chamber. BY rapidly compressing the air you cause its temperature to rise considerably. Well above the auto ignition temperature of the fluid that contains the air. This high temperature air in contact with the surface of the fluid causes that exposed fluid to burn on a microscopic level. This in turn causes combustion byproducts like CO2, CO, oxides of nitrogen (NoX) etc. and soot. These contaminants can over time cause wear and damage to the ABS module assembly. Unfortunately it is impossible to remove every single molecule of "air" from the system so by using the proper procedure when possible and taking you time, you reduce the available amount of entrapped air in the system. Some of you may have experienced an example of entrapped air in a brake system that had what felt like a normal brake pedal after the first bleeding. When you came back several hours/days/weeks/months etc later and bled the system only to find a few bubbles came out during that time. This is because as you initially bleed the system, air intermingled and was dispersed through out the fluid that after time rejoined to form bigger and therefore visible bubbles. SO here is what happens when you do an ABS application to try to remove the air, through the rapidly opening and closing of valves, the pressure rapidly spikes causing the entrapped air temperature to spike well above the auto ignition temperature of the fluid and therefore it burns at that junction of fluid/air. This is a microscopic action but depending on how aerated the fluid is, it can cover a considerable amount of surface area.

Over time, through wear of components and contaminants like moisture/air etc., brake fluid becomes "dirty" Some of that "dirt" is also from combustion that takes place. SO best possible practice is to fill the system slowly, allow time for entrapped air to rise to the surface in the reservoir then slowly bleed the system. That automated bleed opens and closes the valves at a slow rate (in the order of several seconds of dwell time per valve) to prevent temperature spikes and reduce intermingling of air/fluid. Whereas an ABS stop opens and closes those valves at a rate of dozens to hundreds of time per second. Remember time verses pressure, short rise time and high pressure causes high temperature but slow rise time and same high pressure causes little if any temperature rise.

For a condensed history and explanation of ABS systems, ABS Explanation and History

 

Nice summary, Countyjag.

I'll let Darren speak for himself, but upon re-reading his reply to your earlier question (about using a scanner to "automatically" bleed the ABS), my understanding is that bleeding the ABS is done with the bleed screws closed. The purpose of this step is to move the air through the ABS and into the downstream piping. Then you can proceed to regular bleeding (by pressure, vacuum, or pumping the pedal) to actually remove the air from the brake system.

I'm thinking I did much the same thing on my car by activating the ABS through hard braking followed by another bleed.

Do I have that right, Darren?