EdFielder

The power boost has failed on my 88 XJ 6- self levelling suspension still
works fine, and the fluid in the pump is ok- Any one know of some simple
tests to determine the problem area?
Thanks in advance.

webserve

Most likely, if the fluid levels are fine but you are getting no boost --
the accumulator is gone. A simple test is to start the car and bring it
all up to operating levels. Turn off the engine then pump the brakes. The
pedal should not get hard for at least 15-20 pumps If it does, you will
have to replace the black ball located on the right side of the car tucked
up above the suspension. You can only see it from underneath.

Webserve


"EdFielder" <Edshomeshop@hotmail.com> wrote in message
news:OGuze.19287$eM6.9225@newsread3.news.atl.earthlink.net...
> The power boost has failed on my 88 XJ 6- self levelling suspension still
> works fine, and the fluid in the pump is ok- Any one know of some simple
> tests to determine the problem area?
> Thanks in advance.
>
>

EdFielder

Thanks,
I tried your suggestion, and I have no power with motor off, so I am
guessing the accumulator or maybe the booster. I think I will break one of
the lines going into the booster to see if there is pressure.
"webserve" <webserve00@hotmail.com> wrote in message
news:e0674$42ceb86b$452821fb$14692@ALLTEL.NET...
> Most likely, if the fluid levels are fine but you are getting no boost --
> the accumulator is gone. A simple test is to start the car and bring it
> all up to operating levels. Turn off the engine then pump the brakes. The
> pedal should not get hard for at least 15-20 pumps If it does, you will
> have to replace the black ball located on the right side of the car tucked
> up above the suspension. You can only see it from underneath.
>
> Webserve
>
>
> "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> news:OGuze.19287$eM6.9225@newsread3.news.atl.earthlink.net...
> > The power boost has failed on my 88 XJ 6- self levelling suspension
still
> > works fine, and the fluid in the pump is ok- Any one know of some simple
> > tests to determine the problem area?
> > Thanks in advance.
> >
> >
>
>

webserve

On the '88 XJ40, the accumulator IS the booster!! Unlike vacuum/air
boosters with a separate servo, the XJ40 uses a liquid booster system. The
pump on the front of the engine creates the pressure when the engine is
started. It builds pressure in the system to between 1200 and 1500 PSI, When
you step on the brakes, this pressures is released to assist in the braking
process. The accumulator is simply a Nitrogen filled ball with a rubber
diaphragm. Over the years of use, the HSMO (mineral oil) permeates the
diaphragm and releases the Nitrogen and thus the pressure.

If you are getting no power assist when the engine is off than this is most
likely your problem. The system is designed so that in the event of engine
failure whilst driving you will still have power assist with the engine off
to aid in braking.
I am surprised, however that you have no warnings as to low pressure on the
dash.

Webserve.


"EdFielder" <Edshomeshop@hotmail.com> wrote in message
news:inEze.6737$aY6.756@newsread1.news.atl.earthlink.net...
> Thanks,
> I tried your suggestion, and I have no power with motor off, so I am
> guessing the accumulator or maybe the booster. I think I will break one
of
> the lines going into the booster to see if there is pressure.
> "webserve" <webserve00@hotmail.com> wrote in message
> news:e0674$42ceb86b$452821fb$14692@ALLTEL.NET...
> > Most likely, if the fluid levels are fine but you are getting no
boost --
> > the accumulator is gone. A simple test is to start the car and bring
it
> > all up to operating levels. Turn off the engine then pump the brakes.
The
> > pedal should not get hard for at least 15-20 pumps If it does, you
will
> > have to replace the black ball located on the right side of the car
tucked
> > up above the suspension. You can only see it from underneath.
> >
> > Webserve
> >
> >
> > "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> > news:OGuze.19287$eM6.9225@newsread3.news.atl.earthlink.net...
> > > The power boost has failed on my 88 XJ 6- self levelling suspension
> still
> > > works fine, and the fluid in the pump is ok- Any one know of some
simple
> > > tests to determine the problem area?
> > > Thanks in advance.
> > >
> > >
> >
> >
>
>

EdFielder

There is a boost cylinder between the pedal and the master cylinder, which
gets its pressure from the accumulator, so I need to determine if there is
pressure coming from the accumulator to this cylinder. I do have the low
pressure warning, but my digital dash also gives me a series of warnings
about various other faults which are non-existant- I thnk that is an issue
with the electronics.
"webserve" <webserve00@hotmail.com> wrote in message
news:d9f5e$42cfb1ad$452821fb$11654@ALLTEL.NET...
> On the '88 XJ40, the accumulator IS the booster!! Unlike vacuum/air
> boosters with a separate servo, the XJ40 uses a liquid booster system. The
> pump on the front of the engine creates the pressure when the engine is
> started. It builds pressure in the system to between 1200 and 1500 PSI,
When
> you step on the brakes, this pressures is released to assist in the
braking
> process. The accumulator is simply a Nitrogen filled ball with a rubber
> diaphragm. Over the years of use, the HSMO (mineral oil) permeates the
> diaphragm and releases the Nitrogen and thus the pressure.
>
> If you are getting no power assist when the engine is off than this is
most
> likely your problem. The system is designed so that in the event of
engine
> failure whilst driving you will still have power assist with the engine
off
> to aid in braking.
> I am surprised, however that you have no warnings as to low pressure on
the
> dash.
>
> Webserve.
>
>
> "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> news:inEze.6737$aY6.756@newsread1.news.atl.earthlink.net...
> > Thanks,
> > I tried your suggestion, and I have no power with motor off, so I am
> > guessing the accumulator or maybe the booster. I think I will break one
> of
> > the lines going into the booster to see if there is pressure.
> > "webserve" <webserve00@hotmail.com> wrote in message
> > news:e0674$42ceb86b$452821fb$14692@ALLTEL.NET...
> > > Most likely, if the fluid levels are fine but you are getting no
> boost --
> > > the accumulator is gone. A simple test is to start the car and bring
> it
> > > all up to operating levels. Turn off the engine then pump the brakes.
> The
> > > pedal should not get hard for at least 15-20 pumps If it does, you
> will
> > > have to replace the black ball located on the right side of the car
> tucked
> > > up above the suspension. You can only see it from underneath.
> > >
> > > Webserve
> > >
> > >
> > > "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> > > news:OGuze.19287$eM6.9225@newsread3.news.atl.earthlink.net...
> > > > The power boost has failed on my 88 XJ 6- self levelling suspension
> > still
> > > > works fine, and the fluid in the pump is ok- Any one know of some
> simple
> > > > tests to determine the problem area?
> > > > Thanks in advance.
> > > >
> > > >
> > >
> > >
> >
> >
>
>

webserve

If you are not getting pressurized brakes with the motor off for 10-15 pumps
of the pedal, it is the accumulator. This is the standard test for the
accumulator. Amazingly, when I got my '88 5 years ago, I had 7
warnings at one time or another. Not ONE of them proved to be false. Some
proved to be because of faulty solder joints but there was a cause for the
warning. I now have 208,000+ miles on the clock and no warnings except for
those that are supposed to appear at start-up or those that actually are
warning of a problem.

Webserve



"EdFielder" <Edshomeshop@hotmail.com> wrote in message
news:4fQze.136$oZ.26@newsread2.news.atl.earthlink.net...
> There is a boost cylinder between the pedal and the master cylinder, which
> gets its pressure from the accumulator, so I need to determine if there is
> pressure coming from the accumulator to this cylinder. I do have the low
> pressure warning, but my digital dash also gives me a series of warnings
> about various other faults which are non-existant- I thnk that is an issue
> with the electronics.
> "webserve" <webserve00@hotmail.com> wrote in message
> news:d9f5e$42cfb1ad$452821fb$11654@ALLTEL.NET...
> > On the '88 XJ40, the accumulator IS the booster!! Unlike vacuum/air
> > boosters with a separate servo, the XJ40 uses a liquid booster system.
The
> > pump on the front of the engine creates the pressure when the engine is
> > started. It builds pressure in the system to between 1200 and 1500 PSI,
> When
> > you step on the brakes, this pressures is released to assist in the
> braking
> > process. The accumulator is simply a Nitrogen filled ball with a rubber
> > diaphragm. Over the years of use, the HSMO (mineral oil) permeates the
> > diaphragm and releases the Nitrogen and thus the pressure.
> >
> > If you are getting no power assist when the engine is off than this is
> most
> > likely your problem. The system is designed so that in the event of
> engine
> > failure whilst driving you will still have power assist with the engine
> off
> > to aid in braking.
> > I am surprised, however that you have no warnings as to low pressure on
> the
> > dash.
> >
> > Webserve.
> >
> >
> > "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> > news:inEze.6737$aY6.756@newsread1.news.atl.earthlink.net...
> > > Thanks,
> > > I tried your suggestion, and I have no power with motor off, so I am
> > > guessing the accumulator or maybe the booster. I think I will break
one
> > of
> > > the lines going into the booster to see if there is pressure.
> > > "webserve" <webserve00@hotmail.com> wrote in message
> > > news:e0674$42ceb86b$452821fb$14692@ALLTEL.NET...
> > > > Most likely, if the fluid levels are fine but you are getting no
> > boost --
> > > > the accumulator is gone. A simple test is to start the car and
bring
> > it
> > > > all up to operating levels. Turn off the engine then pump the
brakes.
> > The
> > > > pedal should not get hard for at least 15-20 pumps If it does, you
> > will
> > > > have to replace the black ball located on the right side of the car
> > tucked
> > > > up above the suspension. You can only see it from underneath.
> > > >
> > > > Webserve
> > > >
> > > >
> > > > "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> > > > news:OGuze.19287$eM6.9225@newsread3.news.atl.earthlink.net...
> > > > > The power boost has failed on my 88 XJ 6- self levelling
suspension
> > > still
> > > > > works fine, and the fluid in the pump is ok- Any one know of some
> > simple
> > > > > tests to determine the problem area?
> > > > > Thanks in advance.
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>

EdFielder

I have heard of the solder joint issue, that may be my problem, because all
my lights are working, brake fluid up, washer full etc, but still get the
warning light. By the way, my car has 287000 on the clock with the original
engine/trans. It is really an amazing piece of work, because the car still
runs tight and smooth. There is another good support group at
www.motorscarsltd.com as well. I may try changing the accumulator if I can
find one at a reasonable price- just hate to start replacing parts and find
its the 900.00 pump that's out.

"webserve" <webserve00@hotmail.com> wrote in message
news:38933$42d061fa$452821fb$25795@ALLTEL.NET...
> If you are not getting pressurized brakes with the motor off for 10-15
pumps
> of the pedal, it is the accumulator. This is the standard test for the
> accumulator. Amazingly, when I got my '88 5 years ago, I had 7
> warnings at one time or another. Not ONE of them proved to be false.
Some
> proved to be because of faulty solder joints but there was a cause for the
> warning. I now have 208,000+ miles on the clock and no warnings except
for
> those that are supposed to appear at start-up or those that actually are
> warning of a problem.
>
> Webserve
>
>
>
> "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> news:4fQze.136$oZ.26@newsread2.news.atl.earthlink.net...
> > There is a boost cylinder between the pedal and the master cylinder,
which
> > gets its pressure from the accumulator, so I need to determine if there
is
> > pressure coming from the accumulator to this cylinder. I do have the
low
> > pressure warning, but my digital dash also gives me a series of warnings
> > about various other faults which are non-existant- I thnk that is an
issue
> > with the electronics.
> > "webserve" <webserve00@hotmail.com> wrote in message
> > news:d9f5e$42cfb1ad$452821fb$11654@ALLTEL.NET...
> > > On the '88 XJ40, the accumulator IS the booster!! Unlike vacuum/air
> > > boosters with a separate servo, the XJ40 uses a liquid booster system.
> The
> > > pump on the front of the engine creates the pressure when the engine
is
> > > started. It builds pressure in the system to between 1200 and 1500
PSI,
> > When
> > > you step on the brakes, this pressures is released to assist in the
> > braking
> > > process. The accumulator is simply a Nitrogen filled ball with a
rubber
> > > diaphragm. Over the years of use, the HSMO (mineral oil) permeates the
> > > diaphragm and releases the Nitrogen and thus the pressure.
> > >
> > > If you are getting no power assist when the engine is off than this is
> > most
> > > likely your problem. The system is designed so that in the event of
> > engine
> > > failure whilst driving you will still have power assist with the
engine
> > off
> > > to aid in braking.
> > > I am surprised, however that you have no warnings as to low pressure
on
> > the
> > > dash.
> > >
> > > Webserve.
> > >
> > >
> > > "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> > > news:inEze.6737$aY6.756@newsread1.news.atl.earthlink.net...
> > > > Thanks,
> > > > I tried your suggestion, and I have no power with motor off, so I am
> > > > guessing the accumulator or maybe the booster. I think I will break
> one
> > > of
> > > > the lines going into the booster to see if there is pressure.
> > > > "webserve" <webserve00@hotmail.com> wrote in message
> > > > news:e0674$42ceb86b$452821fb$14692@ALLTEL.NET...
> > > > > Most likely, if the fluid levels are fine but you are getting no
> > > boost --
> > > > > the accumulator is gone. A simple test is to start the car and
> bring
> > > it
> > > > > all up to operating levels. Turn off the engine then pump the
> brakes.
> > > The
> > > > > pedal should not get hard for at least 15-20 pumps If it does,
you
> > > will
> > > > > have to replace the black ball located on the right side of the
car
> > > tucked
> > > > > up above the suspension. You can only see it from underneath.
> > > > >
> > > > > Webserve
> > > > >
> > > > >
> > > > > "EdFielder" <Edshomeshop@hotmail.com> wrote in message
> > > > > news:OGuze.19287$eM6.9225@newsread3.news.atl.earthlink.net...
> > > > > > The power boost has failed on my 88 XJ 6- self levelling
> suspension
> > > > still
> > > > > > works fine, and the fluid in the pump is ok- Any one know of
some
> > > simple
> > > > > > tests to determine the problem area?
> > > > > > Thanks in advance.
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>

webserve

I think if you ask Phil Prince at Motorcars Unlimited, he will say the same
thing regarding the accumulator. It is an Extremely common problem with the
'87, '88 and '89 XJ40 with the Girling braking system. Also go to
www.jag-lovers.org and search the archives for "accumulator" You are best
off searching the Moderns group since your symptoms were discussed for
months, 4-5 years ago.

Get an after market unit. They generally run $250-$300 depending. You want
the JLM11659 NOT the JLM1904. The JLM1904 is for the 1990-1994 Teves
system and won't work on your 3.6 litre. I bought mine from these guys
http://www.prestige-spares.com.au/ back in 2001. I bought the JLM11659R
because it was less AND it is rechargable. It also carries a slightly
higher pressure so the pump cycles less. Current price is $192USD plus
around $10USD shipping. I would think you can get the same deal or close
here in the States.

Another easy test, although not AS easy, is to pump the brakes til they get
hard and then simply remove the accumulator. You will lose very little
"Green Blood" Take a pencil and with the ERASER end of the pencil, slide it
into the opening. If it goes much past the threaded collar and into the ball
itself, you need a new accumulator. With 1200 PSI on the other side of the
neoprene diaphram, the eraser should hit rubber nearly immediately after
entering the chamber itself.

In terms of the problem being with the booster -- it is possible -- but I
doubt it. I have yet to hear of a booster being a problem with these cars,
but I am sure someone - some where has had the problem. The accumulator,
however IS a common problem.

In terms of doing re-solder work. I have often wondered, after spending
time on these cars, how the Brits keep aircraft in the air!! Usually, if
you are having a bulb failure warning, it is the module that needs a
re-solder. Anti-lock is usually the tall relay by the petrol inlet in the
boot. Pads low usually means the wire has broken on one of the 4 sensor
wires. The clock re-setting to 12 is re-solder. Usually anything involving
a circuit board can be corrected with a re-solder.

EdFielder

Well, I went ahead and bought a new accumulator from Motorcars and installed
it- still no power brakes. I did the pencil test on the old unit and it was
dead- pencil ( piece of wire) went in all the way- must have 2 problems
going on
I noticed that I was getting some vapor from the fluid reservoir, and pulled
the little cap and depressed the check valve- there is fluid right up to the
top- how do you open that cap to look in the reservoir?
"webserve" <webserve00@hotmail.com> wrote in message
news:72208$42d127d6$45282aca$31959@ALLTEL.NET...
> I think if you ask Phil Prince at Motorcars Unlimited, he will say the
same
> thing regarding the accumulator. It is an Extremely common problem with
the
> '87, '88 and '89 XJ40 with the Girling braking system. Also go to
> www.jag-lovers.org and search the archives for "accumulator" You are best
> off searching the Moderns group since your symptoms were discussed for
> months, 4-5 years ago.
>
> Get an after market unit. They generally run $250-$300 depending. You
want
> the JLM11659 NOT the JLM1904. The JLM1904 is for the 1990-1994 Teves
> system and won't work on your 3.6 litre. I bought mine from these guys
> http://www.prestige-spares.com.au/ back in 2001. I bought the JLM11659R
> because it was less AND it is rechargable. It also carries a slightly
> higher pressure so the pump cycles less. Current price is $192USD plus
> around $10USD shipping. I would think you can get the same deal or close
> here in the States.
>
> Another easy test, although not AS easy, is to pump the brakes til they
get
> hard and then simply remove the accumulator. You will lose very little
> "Green Blood" Take a pencil and with the ERASER end of the pencil, slide
it
> into the opening. If it goes much past the threaded collar and into the
ball
> itself, you need a new accumulator. With 1200 PSI on the other side of
the
> neoprene diaphram, the eraser should hit rubber nearly immediately after
> entering the chamber itself.
>
> In terms of the problem being with the booster -- it is possible -- but I
> doubt it. I have yet to hear of a booster being a problem with these
cars,
> but I am sure someone - some where has had the problem. The accumulator,
> however IS a common problem.
>
> In terms of doing re-solder work. I have often wondered, after spending
> time on these cars, how the Brits keep aircraft in the air!! Usually, if
> you are having a bulb failure warning, it is the module that needs a
> re-solder. Anti-lock is usually the tall relay by the petrol inlet in the
> boot. Pads low usually means the wire has broken on one of the 4 sensor
> wires. The clock re-setting to 12 is re-solder. Usually anything
involving
> a circuit board can be corrected with a re-solder.
>
>
>
>

webserve

I am sorry to hear that the accumulator replacement did not solve the
problem. It was the easiest and most likely solution.

First off, do not try to open the Green reservoir tank. It is designed in
such a manner that there is an adapter made by Castrol that comes on the
HSMO bottles that pushes in the check valve to fill the tank. Replacement
of this tank will cost you hundred(s) of dollars.


What you must do now is try to figure out which component of the system is
not operating properly. If the Rear shocks are going up and down as they
should, then that is an indicator that the pump is working and building
pressure. My next thought, therefore is that if the pump is working and we
know the accumulator works because it is new, then the pump must not be
pressurizing the accumulator/power assist system. This would indicate that
the charging switch is not operational. It is one of the two switches that
were in your way when you changed the accumulator.

What I have done, is I have posted the hydraulics section for the '87, '88,
'89 XJ40 on the web. Go to http://www.jag420.com/jag%5Fxj40/ and
download the pages and print them out. Click on the little picture and it
will bring up the full size version for printing. These are from the Jaguar
service manual CD. Page 66-02 is a drawing of how the system operates and
what the components are. The rest of the pages are the manual section

I hope this will help.

Webserve


"EdFielder" <Edshomeshop@hotmail.com> wrote in message
news:IyBBe.23104$eM6.5480@newsread3.news.atl.earthlink.net...
> Well, I went ahead and bought a new accumulator from Motorcars and
installed
> it- still no power brakes. I did the pencil test on the old unit and it
was
> dead- pencil ( piece of wire) went in all the way- must have 2 problems
> going on
> I noticed that I was getting some vapor from the fluid reservoir, and
pulled
> the little cap and depressed the check valve- there is fluid right up to
the
> top- how do you open that cap to look in the reservoir?