Hi Hedman

I'll just jump in till Pauls returns, just to get you started but

Your Brake System is the Teves Mk1V with ABS and your Photo is of the ABS Pump with the Black Ball Accumulator and on the other side of your Car is the Teves Mk1V Master Cylinder Actuator

If you decide to change the Brake Pipes and want to Stop the Fluid pouring out of them, then you need to get creative:

Just get an old (Hard Line Brake Pipe) with either a Male or Female end depending on what you need, then chop a bit off and hammer the end without the fitting on closed: Something like as in my Photo, then when you disconnect the Brake Pipe, screw this 'dummy' pipe on to act as a Cap

So you don't lose all the Fluid out of the Reservoir 'or you will have to bleed the rear brakes'
Are you sure its the Calipers and not just a Stuck Brake Pad?

 

OrangeBlossom, thanks for your comments. I originally thought the front pads were worn, but when I got them out they looked brand new with almost no wear. I then decided to see if any of the pistons were stuck in the retracted position — the vehicle sat for more than 15 years before I bought it so I thought this was a possibility. Of the 8 pistons in the 2 front brake calipers, I could only get 2 of them to move. In fiddling around with them, I over extended one of them so it’s now stuck in the fully extended position.

At this point, I decided to take my medicine and ordered replacement calipers from SNG Barratt rather than fool around with trying to rebuild them myself. At the same time I got new brake hoses and track rod ends so I could change those while I had the patient on the table.

For now, I haven’t done anything further besides liberally applying penetrating oil to the bolts securing the calipers in place in anticipation of trying to get them off later this week. So it’s not too late to change course. Having screwed up one of the pistons, I’m trying to follow the “first do no harm” approach!

 

Hi Hedman

Unless you are Extremely Lucky!

You might need more than Penetrating Oil to undo those Caliper Bolts, as 'Greg' and myself have invested in a Mains Powered Impact Wrench (Amazon) which was one of the best pieces of Kit I've ever bought for working on a Car

As undoing those Caliper bolts without one can be a real Nightmare, while the Impact Wrench makes it a Breeze!

The easy way to undo Caliper Bolts using a Mains Powered Impact Wrench (including Photos and a Video)

Have a look at Pages 9 + 10 of my 'Cherry Blossom' Restoration Thread (Link Above) where even a Spanner on the end of a 4ft Scaffolding Pole couldn't undo those Caliper Bolts and how the Impact Wrench did so in just a few Seconds!

 

Following OrangeBlossom’s advice, I went to my local tool store to look at their selection of electric impact wrenches. They were having a sale on their heavy duty model with 1,000 ft lbs of “breakaway” torque. Subscribing to the theory of “if some is good, more is better,” I brought home this beast weighing in at over 8 lbs.

On a lark, I tried to remove the first bolt using a long handled socket wrench. It would not budge despite much huffing and puffing. The impact wrench took it off in seconds.

The hardest part was maneuvering it inside the wheel well and getting good purchase on it before pulling the trigger. Fortunately, I had bought a swivel head attachment that worked wonders.

This may go down as the best tool I have ever purchased!

 

I installed the new front calipers, but skipped replacing the brake hoses for the time being. The old pads had no discernible wear, so I put them in the new calipers, where they slid in easily. I drained the old fluid out of the reservoir using a turkey baster and filled it up brand new fluid.

My wife reluctantly agreed to help with the two-man method for bleeding the brakes, and then proceeded to complain incessantly about having to repeatedly press the brake pedal and how long it was taking. So I did an admittedly hasty job and extracted some amber colored fluid, but didn't get to the point of pulling clear fluid through the new calipers. But I did close them up after pulling a solid stream of liquid so thought I had gotten all the air out.

I took the car out for a test drive and there was no discernible improvement in braking. The pedal was still very soft/spongy and the car does not stop quickly -- so much so that stopping at a light requires more than a normal dose of anticipation. This is the same as it was when I first got the car a few months ago. The only thing different was that this time the brake light came on for about 30 second, then went off. It came back on a few minutes later, then went back off.

So I assumed that I had air trapped in the lines and decided to try re-bleeding the front brakes as a last resort before trying OB's procedure for bleeding the low pressure side of the system as detailed in his very helpful post.

This time I enlisted my daughter who was a much more cooperative assistant and willing to pump the pedal as instructed until the cows came home. I started by drawing some more amber colored brake fluid, then the fluid became much more bubbly (but still amber), until it finally stopped running at all. I tried attaching a vacuum extractor to the bleed nipple while the daughter continued to pump the pedal as instructed, but this only succeeded in drawing a modicum of fluid and a lot of bubbles. As best I can tell, I have reached the point where nothing is now coming out of the bleed valves -- both on the left (driver) and right (passenger) side front brakes. There has been very little (if any) reduction in the amount of brake fluid in the reservoir.

So it appears that somewhere between the reservoir and the caliper something has gone amiss. But where to start???? Do I try bleeding the low pressure side next, or look instead at the actuator valves? Is there some way of whittling down where the problem might be without having to tackle one of these intimidating tasks?

I still have not touched the rear brakes nor tried to bleed them.

Any advice or suggestions would be greatly appreciated.

 

Hey HMan... I'll keep it short!
That is/was a GREAT description and I am very interested in hearing what folks who know have to say about it...
Good work!

 

Actually... I have a question. While you are bleeding and going thru the process of pumping the brakes,,,, how does the peddle feel, react, change??? The FEEL of peddle while bleeding is one of the most important TELLERS of what is or isn't happening...

I don't mean to sound as if I don't understand the danger BUT is it possible to TEACH your wife (don't sound like it, lol) or more likely your daughter to turn the 10mm wrench in SAFETY while YOU pump the brakes?

 

Or maybe just get one of these (or a rebuild kit) and pop it in...? I wouldn't be spending no 700bucks (ever) but it's (70 or 80bucks) worth a shot... Are there lots of used parts to choose from out there for the 94? Any breakers?

https://www.ebay.com/itm/153863365989

 

I think I would have better luck convincing my wife to let me buy another Jag than to get her to turn a wrench!

I pumped the brakes about 20 times prior to putting the wife behind the wheel and it didn’t feel like there was that much resistance.

The wife said that the brake peddle got easier to depress over time. The daughter reported the same thing.

 

JJJ: I’ll take a look. FYI, mine is a ‘89 convertible.

 

If the brake fluid isn't coming out this is a problem. Maybe try rebleeding and see what happens.

My usual procedure for bleeding is I have some clear rubber surgical tubing that make a tight fit on the top of the bleed nipple. I then loop it over something higher than the caliper, such as a coil in the spring. That is to provide some fluid sitting on top of the nipple, so that as the nipple is opened there is no possibility of air coming back in. The end of the tubing will go into a jar, and after a few pumps will get the end under the fluid level. I never bother trying to drain old fluid from the reservoir, it will get pumped through anyway.

I have the person pumping as the "caller" who will direct the person opening and closing the bleed nipple. The person pumping will put pressure on the pedal, and call "open" - the person on the bleed nipple will crack open the nipple. The pedal will go down as one continuous stroke, and at about 85% of pedal travel the person will call "close" and the person at the nipple will close it. The idea is to close the nipple before the end of the pedal stroke, so the fluid is always under pressure to flow through the lines. If the brake pedal bottoms out while the nipple is open it can pull air back into the system. Once the nipple is closed, the pumper can release the pedal and start the process again.

The person at the nipple can watch the fluid and see when no more bubbles come out and when the colour has changed from darker, older fluid to lighter new fluid. When it's clean and bubble free, you are done and go to the next wheel. During the process keep an eye on the reservoir level and top up as necessary, again to make sure no air gets pulled into the system.

I don't like vacuum system because they can pull air past the threads of the bleed nipple into the system, I've never been able to get a good bleed with them.

 

Hi Hedman

Easy to say but

'Don't Panic!' (we've all been there!)

(1) First off you can 'Gravity Bleed' the Front Brakes one side at a time, starting with the side furthest away from the Master Cylinder (no pedal pushing required)

(2) If your Brakes still feel spongy then I would say there is a 95% chance that any Air Leak is coming from the Hard Brake Lines on the Calipers. especially if you had trouble in getting them undone, the problem being that they are so rigid that unless they go back perfect then Air may get in (a very common problem)

So a New Set of Hard Front Caliper Brake Pipes could be the best as well as the least expensive way to hopefully fix that problem or I can show you how to make your own, as I make all my own Brake Pipes

In the event that doesn't work (although it probably will do) providing that you never let the Reservoir run dry, then you could try Bleeding the Low Pressure side of the System before you do the Front Brakes

If that doesn't work then you may have to Bleed the Rear Brakes First, which has to be done in a specific way and is not as scary as it may appear, so try what I've suggested first and if none of that works, we can then move onto 'Plan B'

(3) Have Faith We can Fix it!

 

If your Brakes still feel spongy then I would say there is a 95% chance that any Air Leak is coming from the Hard Brake Lines on the Calipers. especially if you had trouble in getting them undone, the problem being that they are so rigid that unless they go back perfect then Air may get in (a very common problem)

So a New Set of Hard Front Caliper Brake Pipes could be the best as well as the least expensive way to hopefully fix that problem or I can show you how to make your own, as I make all my own Brake Pipes

[/QUOTE]

OB, thanks for the advice. I am trying not to panic, but have to admit that after all the time, effort and $ to replace the calipers, this was a deflating experience. And repairing the valves in the master cylinder/actuator seems like a daunting task.

But I keep reminding myself that this is a marathon not a sprint, and that patience is a virtue.

So my next step will be to remove the rubber brake hose from the connection pipe and see if I can bleed it directly from the hose. Fingers crossed!


Next step (these are the old calipers BTW)

 

Hi Hedman

No don't do it like that

Gravity Bleed the Front Calipers from the Bleed Nipples on the Calipers, one side at a time starting with the one furthest away from the Master Cylinder Actuator

Push a piece of Clear Plastic Tubing over the Front Bleed Nipple on the Caliper and stick the other end of the Tubing in a bottle and then undo the Bleed Nipple and let the Brake Fluid drip through, which could take time and maybe an hour or so but do not try and rush this as it takes as long as it takes (the slower the better)

Keep an eye on the Clear Plastic Tubing that you should be using when you do this and you may see some Air Bubbles starting to move in the Tubing but keep the Free end of the Tubing immersed in Brake Fluid, so that Air cannot be sucked back up

Also make sure that the Reservoir never runs out of Brake Fluid

What you should eventually find is no Air Bubbles left in the Clear Plastic Tubing from the Caliper Nipple to the Bottle you are draining the Fluid into and although it doesn't need saying, do not reuse the Brake Fluid you are draining into the bottle

In the event that you can't get rid of the Bubbles and the Pedal Still feels Spongy, then the Chances are that Air is getting in from the Hard Line Brake Pipe that goes into the Caliper, as there is no 'give' in these and they often cause 'This very problem' when you put them back, if the Hard Brake Pipes don't seat in the Caliper properly

Don't even start thinking about repairing the Master Cylinder, as the chances are its perfectly ok and all you've got to contend with, is nothing more that one of those hard Brake Lines letting in Air (New Hard Brake Pipes already bent into shape) are only about $5 each so well worth getting New ones

Then they can be crossed off the list as a possible cause of the problem

If that doesn't fix it the Next step up is to check the Connections of the Flexible Brake Pipes to the Hard Brake Pipes

So in effect you start from the Caliper and then gradually work back up towards the Master Cylinder although you probably won't need to go past the Flexible Brake Pipes

Did you have a 'Hard Pedal' before you changed the Calipers, even though the Brakes didn't work at that stage?

Did the Reservoir EVER run out of Brake Fluid? as if it did then Bleeding the Rear Calipers 'May not be an option' which is not that difficult providing that you follow the Specific Procedure, which I can tell you about if it gets to that stage, where one of the main requirements is to have a proper Bleed Nipple Spanner

As if you round those Bleed Nipples off, then you could well have a massive problem on your hands (ask me how I know or rather don't!)

Bleeding the Brakes on an XJS is always a bit of a 'Nightmare' especially after something like Changing the Calipers, so well done to you for doing that, as that job isn't always considered to be easy

The Chances are that all you've got is a simple Air Leak that needs Sleuthing out, which can be frustrating and drive you up the wall, although I'll say again that we've all been there

Don't give up 'we've got your back' and this is an expected glitch that is all part and parcel of owning one of the Finest Sports Cars Jaguar ever made
and when its fixed you'll wonder what all the fuss was about!

 

I set up the following before receiving OB’s instructions above not to do it this way. But the results may be informative anyway...




About an eye dropper full of fluid came out initially. Since then, no fluid is coming out at all — either by gravity feed or by having an assistant pump the brakes. When the brake pedal is depressed, there is an asthmatic breathing sound at the bottom of the catch container, but no fluid.

This is for the passenger side on LHD vehicle. I get the same result from the driver’s side.

There is practically no resistance to pushing the brake pedal, other than perhaps mechanical.

The brake pedal has never felt firm since the day I got the car (and before starting any work on it). The reservoir has not gone dry, at least during my ownership.

Not sure what to try next...

 

Hi Hedman

Although it would have been better to start at the Caliper Bleed Nipple then gradually work back, the results that you have been getting all point to Air being Trapped in the Low Pressure side of the System

So Bleed the Low Pressure side of the System first and then try and Bleed the Front Calipers again

If its any Consolation I made the mistake of not doing that myself, the very first time I tried to Bleed the Brakes on an XJS and got absolutely nowhere!

Just be very careful not to break the Plastic Elbow that goes into the Brake Pump when you try and jiggle it out

 

Hi herman,

Apols I've been away a while dealing with other family issues.

After a quick read through, I noticed you had drained the fluid from the reservoir.

So you MUST bleed the low pressure side of the system first. Then do the REAR brakes as per my suggested process. Only then do the front circuits.

Then...tell us how good the pedal now feels!

Good luck

Paul

 

Thanks, Paul. I'm working up the courage to tackle bleeding the low pressure side. Hopefully later today or tomorrow. Will advise how it goes.

 

Paul (or anyone else), a quick (and potentially dumb) question. Can I bleed the rear brakes if the rear wheels are up on ramps, or does the car need to be on jack stands with the wheels unweighted? I would prefer to put the wheels on ramps, but didn't know if it was possible to access the bleed nipples this way...

 

Makes no difference as long as you have access to the bleed nipples.