Sounds like you have finished the rear. Keep in mind that bleeder screws have small holes for a reason and there would be no need to undo the lines. I'd move on to the front, then you should get a good pedal and brakes.

 

I was able to get a stream of fluid from the LR caliper bleeder valve but nothing strong, and while there is fluid in the lines to the right rear caliper, it would not come out the bleeder valve which is why I thought perhaps the rebuilt actuator was not working properly and got another one to try.
So now I am back with a bunch of air in the system and I am not getting a flow even from the LR. Guess I need to just keep trying to get back to where I was, and then put a lot more fluid through the system to make sure there is no air. I may have just given up a bit too soon on the first rebuilt actuator (and my original one).

 

csbush,

A couple of thoughts:

- If you get any fluid to come out of the rear bleed nipples, then you are getting high-pressure to the rear brakes. This is because the only fluid sent to the rear brakes comes from the high-pressure feed to the Actuation Unit. I know it doesn't sound intuitive but the pedal pressure doesn't send any fluid to the rear. The system works by the movement of the pedal opening a shuttle valve which allows fluid from the Accumulator to flow into the Actuation Unit and thence to the rear brakes. The pressure of fluid is limited by a valve which reduces the pressure that is going to the front by 20psi. So if you get any fluid flowing when a rear bleed nipple is opened and you press the pedal, this means that the shuttle valve is being opened. But It doesn't really flow out of the bleed nipple valve at "high-pressure".

- It's a single circuit to the rear, so if you get fluid out of one caliper, it means the Actuation Unit is working (to some degree). If you've got no fluid coming out of one side only, you've got a problem specifically on that side. It could be continued air, or it may be a flexi that has internally collapsed.

I would do 3 things:

- Bleed the rears using the Teves (not Jaguar) procedure again to see if you can get both sides flowing correctly.
- If no improvement, do it again! If no improvement:
- Disconnect the flexis and confirm fluid flows when the pedal is pressed. If no flow, change the flexi. If there is flow, bleed them again. Even try removing the bleed nipple to check it's not blocked or jammed.

Cheers

Paul

 

Thanks- Ill give all that a shot.

 

Have you renewed all the flexibles? If not, I would do so.

 

Yes- new flexible hoses and flushed lines. They were really a mess.

 

Still no progress on the brakes.
Tried again to bleed the rear brakes- used this procedure:


Bleeding procedure

I got nowhere with this. Nothing coming out of the rear bleed nipple or even the lines when I pulled them to see if there was any issues pushing through the caliper.
So I pulled the reservoir off again to make sure it was seated properly. I re-bled the low pressure side, pulling the little 90 degree fitting off and letting clear brake fluid flush through.
I cracked open the high pressure line going into the pump and got seepage- I know it is under a lot of pressure and didn’t want to open it too far. So I know I have high pressure fluid going into the actuator.
Since I wasn’t getting any fluid to the rear, I pulled the metal line for the rear off of the actuator (it is the big one between the lines for the front brakes below the abs block). I have no fluid coming out of the actuator to that line. This makes no sense to me. Perhaps the control valve in my new rebuilt actuator is stuck closed? I know there is air in the system, but this makes no sense and I am stuck. At least with the last actuator, I was able to get fluid to one rear caliper…

 

csbush,

I know you understand the Teves system pretty well now so forgive me if I'm saying things you already know.

In theory, no fluid can flow to the rear until the pedal is moved. Only boosted fluid is sent to the rear and that can only happen if the pedal is depressed and the control.valve opens in the Actuation Unit. So if you crack the line open but don't touch the pedal I wouldn't expect fluid to flow out that line.

Also the abs valve block could be at fault with the valves effectively emulating an ABS lock situation thus preventing fluid exiting to the rear line. Have you checked the state of the rear solenoid valves?

cheers

Paul

 

I thought I had pressure and pushed the pedal with the rear brake line open, but will check that again tomorrow with my helper. Was going to go through it all again.
I will look at the ABS block. It is part of the rebuilt actuator- but…. I assume I can check them by energizing each one with 12V? I know the terminal on the end is ground, so should be able to just go along the line and give each one a shot and listen for the click.

 

Finally got back to working on the brakes. I could not get any fluid out of the actuator at the rear brake line fitting- perhaps the ABS valve was blocking the flow to the actuator fitting- don’t really know, My supplier graciously agreed to send me another actuator, so I installed another one. This one did push fluid through, and I was able to bleed the LR caliper per the bleeding instructions. I could not get fluid out of the RR bleed valve, but cracked the line going into the caliper, and got fluid out of that. I ran enough fluid back there to get any air out of the lines.
I then tried the front caliper traditional bleed process. Again, I get fluid to the calipers but not through the bleeder valve. I tried to push the pedal multiple times, but cannot get it to build pressure. Just the fountain of fluid through the brake reservoir cap which was fun.
I installed my Motive brake bleeder to the reservoir, and pumped it up to about 15 lbs pressure. Got a stronger flow of fluid out of the lines to the front calipers, but still can’t get them to bleed through the valves. I was able to get enough brake pressure to actuate the brakes- I could not turn the front rotors. But when I removed the bleeder, and tried to operate the brakes a few minutes later, was not able to build pressure by pumping the pedal, and just make a mess with the cap fountain.

My guess is I still have some air in the calipers that is preventing me getting brake pressure. Since the calipers were rebuilt a year ago and I did not really test them after I got them back, I am going to remove a caliper, test it on a test stand that a friend has, and see how it responds. Perhaps it is stuck or clogged, and if that is the case working it on the test stand should provide some clarity.

Not entirely optimistic with this strategy, but that is all I’ve got…

 

csbush,

You didn't mention if the replacement Actuation Unit came complete with the ABS valve block attached or if you used your existing ABS valve block? The fluid flow to the wheel circuits always comes from the ABS block not direct from the Actuation Unit.

I suspect that the fault lay in the valve block not in the Actuation Unit - they almost never go wrong.

Anyway, as you've now got fluid flowing to the wheel circuits, it's just a case of sorting out those calipers. Before you take them off the car, just remove the bleed nipples on the troublesome ones and check they are not blocked. It's the most likely problem. Even try gently poikng something in the bleed nipple hole to dislodge any foreign matter. Alternatively, disconnect the input pipe and replace with a feed from a footpump or similar. Then with a hose connected to the (unblocked) bleed nipple to catch the fluid in a jar, try applying some pressure to the pump to force fluid through the caliper. And see if that clears any blockage.

Good luck

Paul

 

Finally success! The brakes now work and I will try and do a test drive this week- my first time driving an XJS!

Paul was on the right track with the bleeder valves. I pulled the bleeder valves and they were cleared, but then I pulled the (freshly rebuilt by a company in the US) front caliper, and dis assembled it so I could check to make sure the new sleeves had the flow ports drilled into them, and to check any fluid passages. Sure enough they were all clear except for the passage to the bleeder valve. I could not even blow compressed air through it. BUT I was able to clear it by hand with a small drill bit. I was full of dried brake fluid gunk. I did the same with other caliper, and it had the same issue. Only one back one was not working, and I didn’t want to pull the caliper, so I just removed the bleeder, cleaned out the bleeder passage, and gravity bled that caliper.
A quick bleeding of the front calipers and I have good brakes now.
Couple of things I learned along the way:
Even if you have your calipers rebuilt, test them before you put them on the car to make sure fluid will flow through them.
Even with a high pressure rear brake system, the pressure is reduced and the fluid just flows through the rear calipers like normal bleeding. I expected a geyser and thought my pressure system was not working properly.
You can find out a lot by cracking open brake lines on the actuator. I figured out I wasn’t getting fluid through the ABS valves on my previous actuator and since I had already paid for a new one, I was able to swap it out for another rebuild. I opened the line to the rear, operated they system, and got brake fluid- so I knew it’s was pushing fluid out to the back. Likewise, I finally isolated the calipers by opening up lines to the calipers and having fluid run out. So I knew the actuator was pushing fluid out to the fronts. It is frustrating though, because until you get all the air out you get no pedal pressure so it feels like you are not pushing any fluid out to bleed the brakes.

 

Got the car registered and was able to take it out for a road test. Did two 15 mile drives with no issues. I need to slowly break in the rebuilt engine. It is running pretty cool- not reaching the middle on the barrel gauge. The aux fan comes on at some point and stays on for a few minutes after I shut the car off which seems normal.
I had never driven an XJS before. It is such a quiet car. Even with the middle mufflers omitted, the exhaust is quiet. It feels like a very heavy car that would have a lot of understeer with that long hood and heavy engine out front, but it handles nicely. I really do enjoy how it just effortlessly glides along. I think the is a project car that my spouse will actually enjoy riding in. I’ll take it for longer drives this week as I have time.

My next big task is getting the climate control system working, but think I will start another thread on that.

Thanks again to everyone for helping me get this far!!!