I have a 1991 XJ40 with a Tevis system. I can be driving along and
have to stop and hit my brakes and then they work. Other times I
can hit the brakes and they go to the floor and lock. The brake
light will come on. I need help. What should I check and how.–
DS1
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In reply to a message from DS1 sent Wed 5 Mar 2008:
Have you checked the obvious first fluid on floor, poor condition
hoses, air in system?
with the engine off and the system depressurised does the pedal
feel hard to press or do the same symtoms appear, there was a
posting on the accululater sphere causing the same symtoms, read
Bryan N’s posting on how the system should charge and how long the
pump should run before you do any spending, the teeves system tends
to be trouble free with only spheres and charge values going wrong.
Regards–
The original message included these comments:
I have a 1991 XJ40 with a Tevis system. I can be driving along and
–
Mick Gannon Daimler 4.0 1991 England
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In reply to a message from DS1 sent Wed 5 Mar 2008:
What do you mean ‘’ go to the floor and lock’’ ?
Do you mean that the brakes stick on so that the car will
not move?
After the Teves pump has stopped running after you’ve first
turned the key to position (I) and then you turn the key to
‘OFF’, how many applications of the brake pedal do you get
before the boost is lost - i.e. the pedal ‘goes hard’? Try
that test using the heel of your hand rather than your foot
Any time the ‘BRAKE’ light illuminates, either you have lost
all boost pressure and/or the brake fluid level is too low
and/or the pad wear sensor is telling you something. The
next time the ‘BRAKE’ light comes on, press the VCM button
and tell us what you see on the LCD screen.–
The original message included these comments:
I have a 1991 XJ40 with a Tevis system. I can be driving along and
have to stop and hit my brakes and then they work. Other times I
can hit the brakes and they go to the floor and lock. The brake
light will come on. I need help. What should I check and how.
–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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In reply to a message from DS1 sent Wed 5 Mar 2008:
When I mean they lock. The system locks. I csan be pumping and get
nothing. They go to the floor and I go into a skid.–
The original message included these comments:
I have a 1991 XJ40 with a Tevis system. I can be driving along and
have to stop and hit my brakes and then they work. Other times I
can hit the brakes and they go to the floor and lock. The brake
–
DS1
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In reply to a message from Bryan N sent Wed 5 Mar 2008:
Thanks,
I am new to the forum, so I don’t know how to get to bryan’s post
to a similar problem. I will give you and example. I was driving a
car pulled out in front. I hit the brakes, I didn’t have any. I
pumped and pumped they went to the floor. I had know control and
just skidded.–
The original message included these comments:
What do you mean ‘’ go to the floor and lock’’ ?
Do you mean that the brakes stick on so that the car will
not move?
–
DS1
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In reply to a message from DS1 sent Wed 5 Mar 2008:
OK, I’m not clear from your description whether you have a
brake boost problem (failed accumulator, electric pump or
boost unit) or an actual brake failure problem due to air in
the system (requires the brakes to be bled) or mechanical
failure of one or more of the brake components (pads,
rotors, calliper pistons, calliper guide pins or brake
master cylinder)
To check out the Teves brake boost efficiency, try this;-
Typically, when my car has been sitting unused so that any
residual pressure in the accumulator has long since
dissipated, on turning on the ignition (without starting the
engine), the pump motor runs, the ABS light extinguishes
after 32 seconds, the ‘BRAKE’ light extinguishes after 35
seconds and the pump stops after 42 seconds.
With the ignition still on, the pump will re-start on the
second application of the brake and run for 3 seconds to
recharge the accumulator.
Then, with the ignition switched off, it usually takes
exactly 30 applications of the brake before the pedal �goes
hard’ when servo assistance (boost) is lost.
How does your car compare with that?
If you skidded to a halt when that car pulled out in front
of you, presumably the wheels locked so you must have brakes
to cause that - or you would have hit the car.
It sounds to me as if you are unfamiliar with car braking
systems and if the brakes are failing, I strongly recommend
that you take the car to be inspected by someone who is
before you have an accident.–
The original message included these comments:
I am new to the forum, so I don’t know how to get to bryan’s post
to a similar problem. I will give you and example. I was driving a
car pulled out in front. I hit the brakes, I didn’t have any. I
pumped and pumped they went to the floor. I had know control and
just skidded.
–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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