I had been posting questions about my brake issue under the "1994 XJS strange happening" thread, but have reached the point where I think it makes sense to start a new thread.

I have a 1989 XJS convertible with just under 40,000 miles. I have no maintenance or service records on the vehicle. At some point in its history, the car sat for 15-16 years without being driven.

When I bought the car over the winter, the brakes were "mushy" -- the pedal feels spongy and the car was slow to come to a stop. So this spring, I decided to see if the brake pads needed replacing.

When I checked the front brakes, the pads were in "like-new" condition. So I thought the pistons had potentially rusted in place so they were not applying pressure to the brake pads. I tried manipulating the pistons with a pair of pliers. I did NOT open the bleed valves first, which I now realize was a mistake. Between the 2 front brakes (8 pistons in total), only 2 would move. The others were locked in place. So I decided to replace the calipers.

After installing the new calipers, I tried bleeding the brakes. I extracted very little fluid using both the 2 man method and a vacuum extractor, and a combination of the 2 man method + vacuum extractor.

I then tried bleeding the low pressure side. Some fluid came out, but it was no where near the "gusher" that orangeblossom had warned me to expect. But I figured, "mission accomplished" and moved on to trying to bleed the rear brakes using the procedure advised by ptsj1.

I was able to extract very little fluid (less than 1/4 cup in total) and the pump would only run for 5-6 seconds before shutting off on its own. Several times the ABS light would not go off and I would have to wait several minutes before trying again. I began to suspect that the fluid from the reservoir was somehow not getting to the pump.

I tried bleeding the low pressure side again. This time, only a trickle of fluid coming out of the connection at the pump. So now I began to suspect that either the reservoir was clogged or there was a blockage somewhere in the line between the reservoir and the pump.

I removed the reservoir and drained it -- and saw brownish liquid with the viscosity of thick maple syrup coming out. So now fairly confident this was the root cause, I thoroughly rinsed out the reservoir, confirmed that water was now "gushing" out of the attached brake hose, and let it thoroughly dry before reinstalling it. To convince myself there was no blockage in the pipe between the reservoir (driver's side of LHD car) and the pump, I attached a plastic bag to the pump side and blew air in the pipe from the reservoir side. The bag quickly inflated, showing no blockage.

I filled the reservoir with clean brake fluid and set to bleeding the rear brakes. Again, very little fluid came out and the pump would cut off after 5-6 seconds. Also had the intermittent issue with the ABS light not going off. I tried both passenger side and drivers side, with no difference.

On a lark, I decided to try again bleeding the front brakes with the ignition off using only the 2 man method of pumping the brakes. After pumping the brakes 5 times, brake fluid started shooting out of the top of the reservoir cap like a thin geyser. Fortunately, none of the fluid landed on the exterior body work!

So having gone back and re-read the PDF on the Teves Mark II system, I think there is a problem with either the control valve or the hydraulic booster.

Does anyone have any better ideas or suggestions of what to do next to better diagnose the problem?

 

Hi Hedman

I once had the same thing happen myself, with Brake Fluid shooting out of the Top of the Reservoir, which in a thread I'm unable to find I called the 'Teves Fountain' the cause of which turned out to be Blocked Brake Pipes, which was somehow causing some sort of back pressure

Where in order to fix this, I took out the Bleed Nipple from each Caliper one at a time and just kept running Brake Fluid through them, until the Brake Pipes unblocked themselves and Brake Fluid would pour out (sometimes aided by the Pedal)

So it does seem highly possible that the gunge you found in the Reservoir, has gummed up the Brake Pipes so that Brake Fluid cannot flow through, so if you can unblock them, then this might solve the problem as it did for me

 

I think that you're going to have to start opening brake lines around the car... For the rear brakes there is a junction under the LH wheel well,,, goes around up there to the back LH top of the cage. There is a soft line there, bolted to the body of the car. Take off the rear tire, unbolt the connection point from the car (maybe) and carefully disconnect the junction. See if the fluid is making it thru and up to as many points that you can access all over the car and start to try to narrow down the block. It's there, somewhere.

No fun, but that's what I would start doing. I like pain, lol

 

After pondering the problem a while, I decided to start by trying to recreate the "Teves Fountain" with the front brakes. Without a partner to help, I started with the drivers side to be better positioned to observe the reservoir cap. I attached a drain hose to the bleed plug, cracked it open, and pumped the brakes about 5 times with the ignition off, keeping a watchful eye on the cap.

This time, there no fountain and I collected a decent amount of clear brake fluid out of the caliper. The brake pedal felt much "firmer" than it had in the past. So it appeared that the new fluid in the reservoir is making its way to the calipers, albeit not in great volume and still mixed with some air.

Before I could do anything else, I needed a way to close the bleed valve without sucking more air back in to the system. I attached the vacuum extractor and gave it a few pumps to create negative air pressure on the bleed valve, then pumped the brakes a few more times before quickly closing the bleed valve. By watching the air bubbles in the hose, I was reasonably confident that it did not suck more air back in to the system. So I moved on and did the same with the passenger side.

With no way to bleed the rear brakes without a helper, I took the car down off the jack stands and drove it slowly around the block to see what more I could learn. When I first turned the ignition on, the ABS light would not go out. So I turned the ignition off and then back on again, the light went out and I started the car.

The brake pedal still felt "firmer" than before, but I had to push the pedal almost all the way to the floor before the brakes would "bite" and bring the car to quick stop. I tested this several times and got the distinct impression that only the front brakes were engaging to stop the car.

The Teves manual indicates that the rear brakes are engaged only by pressurized fluid coming from the accumulator and flowing through the boost piston. The boost piston also uses this pressurized fluid to increase the force applied to the master cylinder which in turn pushes fluid to the front calipers. So it would stand to reason that if there is a fault in the pressurized side of the system, that the front brakes would still work, but would require more mechanical input from the driver to achieve the same result. Which is exactly what I experienced.

In total, the symptoms seem to suggest that I have a problem somewhere in the chain between the reservoir, pump, accumulator and boost piston:
1. I can extract at least some fluid from both the front and rear calipers, indicating the none of the lines are completely blocked
2. There is relatively little pressure pushing fluid out of the rear calipers -- it weeps out of the bleed valve vs. spraying out, suggesting there is limited pressure in the lines
3. Fluid comes under more pressure from the front calipers, but it requires full pedal travel to get anything to come out
4. The front brakes function to stop the car, but only with full pedal travel and the rears do not appear to work at all.
5. When bleeding the low pressure side, fluid only comes out of the hose connection at the pump at a soft trickle, not a "gusher"
6. The ABS light frequently does not extinguish on its own. Shutting the ignition off and then on again will cause the light to go out.
7. When bleeding the rear brakes, the pump will run at most for 5-6 seconds before shutting off on its own. Is there a switch that would cause the pump to cut out if the reservoir ever runs dry to prevent the pump from burning itself out?

So I keep thinking about the soft trickle coming out of the low pressure hose. When I had the reservoir of the car, water would run through it easily, so I don't think the reservoir outlet itself is clogged. I could blow air through the pipe from the reservoir to the pump, so I don't think it is blocked. The reservoir is full of fluid, so it ought to have enough mass to push fluid through to the pump at a decent rate, yet it doesn't.

What am I missing? Is there any way to increase the pressure of the fluid running from the reservoir to the pump to try to push out any crud in the pipes that may be slowing things down?

 

The pump will/might shut off if it is accumulating pressure. Pressure caused by a block in the line somewhere on the high pressure side of the low pressure system which engages the back brakes. For instance, under the reservoir, the area under the master cylinder, is a "pressure reducing/regulator valve" or something like that. If you said that the brake fluid was wet, contaminated, ran like syrup (I'm sorry I cannot and will not go back and read thru the entire first thread) you HAVE to open the line at that point and see if the internals of that gizmo has failed and fallen apart inside and blocked the line. If it's not blocked there go to the soft line just where the the line from under the car turns up and starts to make its way to the cage, open the line there. If not there, the next one and then the next. There is more to this system than the bleed nipples and the brake peddle...

There are other points from the MC and reservoir to the rear brakes, there is a T that separates the main line coming to the rear brakes to the L and R caliper. Could be gummed up or blocked. Open that set of fittings and see if fluid is reaching that point.

You can bleed brakes by yourself. Take a clear DRY plastic bottle, fill it halfway with brake fluid, run a clear 1/4 inch line from the bleed nipple (press it over andthe nipple) insert the end of the tube submerged into the bottle. Drill a small hole in the CAP of the bottle to secure the hose into the fluid in the bottle. Starting with either front brake - pump the peddle until the line is full, no air, that way when you DO go to close the bleeder only fluid from the hose and bottle will be pulled back into the caliper.

You have to start systematically opening the fittings/connections of brake lines of the lines in question. Replacing steel lines if necessary...

Have you COMPLETELY removed the pump yet?

Watch some videos of flare and inverted flare fittings, , and get down and dirty...










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This way, you could further PACK the crud in there, or into the pump, or what have you.

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Hi Hedman

It looks like you are starting to get somewhere although there seems to be plenty of 'Treacle' still Blocking up those Brake lines all of which still needs to be removed

There is No Switch to Stop the Brake Pump in the event that the Reservoir Runs dry, so you do need to be Careful not to burn out the Brake Pump especially if you find that it is starting to get hot

If you want to increase the Pressure in the Reservoir on order to help to force the Bad Stuff out, then you can do so using a 'Pressure Bleeder' which screws on to the Top of the Reservoir in place of the Reservoir Cap and these are also fairly inexpensive to buy

Don't connect this to a Compressor! as you need to use the lowest pressure that will do the job, or you could end up by blowing the Pressure Bleeder Cap off the Top of the Reservoir and end up Splashing Brake Fluid everywhere

So when you have the Pressure Bleeder Connected lay an old Towel over the Top before connecting the Air just in case the worst should happen

You only need to use a very Low Pressure, like you might get from a Tire that is almost deflated, as the Pressure Bleeder has a Clip that goes onto a Tire Valve the same as you use for pumping a Tire up

The Front Brakes should be easy enough and if you are using a Pressure Bleeder then you may not have to Bleed the Low Pressure side but when you do the Rear Brakes you still need to use the method described by Ptjs 'Paul'

A Gunson Pressure Bleeder (or similar) is what you need if you can get one your side of the Pond

Hope this helps

Good Luck

Alex

 

Hedman
Have you undone the flexible between the body and the rear subframe? This is known to collapse internally and block. I would undo and renew this item next.

 

Thanks, Greg. I’ll take a look at this next.

 

JJJ: thanks for the suggestion. Is the location of the junction you referenced for a LHD or RHD car?

 

Sorry Brother. Good point. I would imagine everything would be in the same place just on opposite side. But I am unsure. Greg, Grant and Doug walked me thru DELETING mine when mine failed. It is an unmistakable looking thing. Under the reservoir and master cylinder,,, it's a 3 inch or so six sided (that a wrench could go over) junction. In that (depending on which junction you're asking about) the rubber flexible at the cage might be on the opposite side of the car than mine too, under the RH rear wheel area.

For me, the thought of removing things and taking things apart used to be VERY painful (and can often lead to OTHER THINGS) but it is becoming less and less painful. I still resist it. But, often, it is the ONLY way. Damn carz...

 

Still puzzled by the bare trickle of brake fluid when I tried to bleed the low pressure side, I decided to start with the pipe connecting the reservoir to the pump and to work from there to the to the rear brake hoses and junction as suggested by JJJ and Greg.

I removed the plastic connector from the pump and removed the reservoir for a second thorough cleaning just in case. While I was waiting for the reservoir to dry, I decided to try to flush out the copper brake line that feeds the pump.

I attached about 5 feet of hose to the line where it connects with the reservoir, held the hose so it was rising straight up out of the car to take advantage of gravity, and used a funnel to pour in about a quart of windshield washer fluid.

Why windshield washer fluid? I wanted something that wouldn’t strip the paint off in case it splashed everywhere and something brightly colored so I could distinguish it from brake fluid.

At first, nothing happened. Then a small quantity of brake fluid was spit out of the pump end of the line, followed by a gyser of windshield washer fluid. See photos below...



The old fluid that was spit out

Followed by washer fluid


I flushed the line with brake fluid, reattached the reservoir and filled it. I was then able to bleed all 4 brakes with no problem!

 

Damn, Brother!!! Good show!!! Damn good show.
You must feel right good!!!

Doesn't stuff like that feel good!

Cheers me up and gives me hope, I got problems today.
My car sat for like 12yrs. And it's been a bit to clear up the problems. Good to see someone doing stuff!

Be well!

 

Just to add.

H20 is the enemy of brake systems. See what you can do to completely dry the washer fluid. Lucky it evaporates pretty good compared to water but ya got to get rid of it all, somehow. Can ya use a hair dryer to now push hot air thru it, lol... OMGOODNESS these cars!!!

 

JJJ: Thanks for your words of encouragement. I was wary about intentionally introducing water into the brake line, but I ran a bunch of brake fluid through the line afterwards to flush out any residual washer fluid.

My only problem is that now that my attention is not fully consumed by the brakes not working, I realized that the rear end drives like it is swimming in a bath of oatmeal. So it looks like I need to replace the rear springs and shocks, which I assume that I can only do by dropping out the rear cage. So one relatively small task checked off the list and one rather large one added to it!

 

Others will chime in,,, but not true.

I could be wrong but from what I understand removal of the rear shocks/springs is fairly easy and straight forward - cage in. All 4 springs can be found for under 120 combined,,, shocks will cost ya. I hear Boges'. You will need to get a spring compressor which can be GOT at your local big box auto parts supplier. Fronts are pretty reasonable, and such...

Good good work man.

 

Quite correct JJJ. Rear spring shockers can be removed with just the wheel off and the car jacked up. Also, for the OP, look at the radius arm bushes too, they might also be the cause of some poor rear end symptoms.

 

No cage drop is music to my ears! Is there a thread somewhere that describes how to replace the rear shocks and springs without dropping the cage?

 

Not yet! proceed as follows, one side at a time:

• jack up car
• remove one rear road wheel
• undo the pin that secures the bottom of the shock to the lower wishbone arm; NOTE what washers go where
• support the lower wishbone/hub and drive the pin out towards the front from the rear using a brass drift
• the shocks are now free at the bottom
• at the top there is a bolt holding each shocker, it goes through a bracket and through the cage.
• undo the bolt, one spanner on the fixing on the outside the cage one inside by the shocker bracket. Note OEM thee nut is one size and the bolt another! 5/8th and 11/16ths from memory. Access is tricky but is it doable.
• remove the spring/shocker a a unit.

 

You'll find that. Yes.

In essence it's just about taking things apart being careful and certain everything goes back in the same order, in the same spot. I personally have NOT done this yet, want to and will. Folks here will help with the step by...

The trailing arms can be tougher to deal with for the home mechanic on some cars than others but it's also not so so bad. When you get there, start a thread.

Dude. Do make sure that you run all of that H2O out of the brake system. It's important