billbobben
New Member
Hi All,
I will post in the introduce yourself thread as well shortly.
But first
1998 P38 Diesel (bmw engine) lhd.
The brakes failed. Symptoms are no brakes...... the emergency or secondary brake circuit works on the front wheels.
The relay to run the pump is good, opened, cleaned, checked, all good.
The pump runs when you short its live feed from the fuse box.
But the system holds no pressure at all.
With the pump running we have full braking, when the pump stops only emergency brakes.
Main dealers said there was a problem with the modulator.
We changed the plastic washers on the top valve (shuttle valve?)in the modulator for stainless steel ones using a kit from an Australian. No difference.
So, question, if the modulator was the issue surely we should still have pressure being stored?
If the accumulator was tired surely the pump should just run on and on.
But there is no stored pressure and the pump only runs when shorted.
Does this point to the pressure switch (my first choice) or could it be an issue with the modulator?
I don't want to open up the modulator again and start messing with the bottom where the valves are as I have found no instructions anywhere on the web for how to do this, nor any kits of seals etc. I don't want to pull the pressure switch unless I am 90% that it is the problem.
Any views on whether the switch or the modulator is the issue would be welcome.
Any second hand parts are as rare as rocking horse poo in Estonia so it is not so simple to just get spare parts to try out. I need a good idea of what to get sent over from the UK before I start throwing money around.
And please don't ask about diagnostics, the BECM doesn't talk to anyone, not even the dealers.....
Thanks
I will post in the introduce yourself thread as well shortly.
But first
1998 P38 Diesel (bmw engine) lhd.
The brakes failed. Symptoms are no brakes...... the emergency or secondary brake circuit works on the front wheels.
The relay to run the pump is good, opened, cleaned, checked, all good.
The pump runs when you short its live feed from the fuse box.
But the system holds no pressure at all.
With the pump running we have full braking, when the pump stops only emergency brakes.
Main dealers said there was a problem with the modulator.
We changed the plastic washers on the top valve (shuttle valve?)in the modulator for stainless steel ones using a kit from an Australian. No difference.
So, question, if the modulator was the issue surely we should still have pressure being stored?
If the accumulator was tired surely the pump should just run on and on.
But there is no stored pressure and the pump only runs when shorted.
Does this point to the pressure switch (my first choice) or could it be an issue with the modulator?
I don't want to open up the modulator again and start messing with the bottom where the valves are as I have found no instructions anywhere on the web for how to do this, nor any kits of seals etc. I don't want to pull the pressure switch unless I am 90% that it is the problem.
Any views on whether the switch or the modulator is the issue would be welcome.
Any second hand parts are as rare as rocking horse poo in Estonia so it is not so simple to just get spare parts to try out. I need a good idea of what to get sent over from the UK before I start throwing money around.
And please don't ask about diagnostics, the BECM doesn't talk to anyone, not even the dealers.....
Thanks
