'STOP' Light
Moderator: RichardW
'STOP' Light
Hi all, when starting my 1.9TD the STOP light stays on for about 10 - 15 seconds. Ive checked the hydraulic fluid and thats fine, does anyone have any suggestion please. Thanks in advance.
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Dave Burns
- Posts: 1915
- Joined: 14 May 2001, 05:30
- Location: United Kingdom
- My Cars:
- x 2
The best indicator's as to the sphere's condition without proper testing are the cut in/out intervals of the regulator, and the sound of escaping pressure as the pressure reliefe screw is opened.
An acc. sphere that has got very little gas pressure left will need much more oil pumped in to it which will lengthen the time before the stop light extinguishes.
Taking values as given and not necessarily the actual values (i.e actual internal cavity/volume of the sphere, operating pressure of s/valve) so this is an approximation, in a good system the pump will only have to force 125cc of oil into the sphere to increase the pressure from rest at 62 bar to 90 bar, this is approximately the pressure at which the security valve opens and the stop light goes out.
If for instance the acc. sphere only has a gas pressure at rest of 5 bar instead of 62, then the pump will have to supply nearly the entire 400cc that will all but fill the sphere before the pressure rises to the 90 bar required to operate the valve and light.
When the sphere has failed totaly and possibly ruptured, it will remain full of oil since there is no gas pressure left to push it out, then the warning light will extinguish very quickly as there is nothing that can be compressed and high pressure is developed as soon as the engine begins to turn.
So the warning light either going off too soon or too late could both be a pointer to a bad acc. sphere.
If anyone knows the pump output per revolution it could give us a good idea how long it really should take with a known good sphere.
Dave
An acc. sphere that has got very little gas pressure left will need much more oil pumped in to it which will lengthen the time before the stop light extinguishes.
Taking values as given and not necessarily the actual values (i.e actual internal cavity/volume of the sphere, operating pressure of s/valve) so this is an approximation, in a good system the pump will only have to force 125cc of oil into the sphere to increase the pressure from rest at 62 bar to 90 bar, this is approximately the pressure at which the security valve opens and the stop light goes out.
If for instance the acc. sphere only has a gas pressure at rest of 5 bar instead of 62, then the pump will have to supply nearly the entire 400cc that will all but fill the sphere before the pressure rises to the 90 bar required to operate the valve and light.
When the sphere has failed totaly and possibly ruptured, it will remain full of oil since there is no gas pressure left to push it out, then the warning light will extinguish very quickly as there is nothing that can be compressed and high pressure is developed as soon as the engine begins to turn.
So the warning light either going off too soon or too late could both be a pointer to a bad acc. sphere.
If anyone knows the pump output per revolution it could give us a good idea how long it really should take with a known good sphere.
Dave
My Haynes describes the pump as 'five piston volumetric, speed - half engine speed (which I do not believe to be true) and the output per pump cycle - 4cc.
As a matter of interest Haynes describes the GS pump as Single cylinder piston type, driven at half engine speed, piston diameter 15 mm, stroke, 10 mm and output under load of 175 bar (2490 psi) of 0.9cc per rev at 250 rpm. The drive is a connecting rod from the oil pump so presumably this is engine speed.
Jeremy
As a matter of interest Haynes describes the GS pump as Single cylinder piston type, driven at half engine speed, piston diameter 15 mm, stroke, 10 mm and output under load of 175 bar (2490 psi) of 0.9cc per rev at 250 rpm. The drive is a connecting rod from the oil pump so presumably this is engine speed.
Jeremy
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Dave Burns
- Posts: 1915
- Joined: 14 May 2001, 05:30
- Location: United Kingdom
- My Cars:
- x 2
Hi Jeremy, half engine speed would be on the BX I assume, if the pump drive pulley on the camshaft and the on the pump its self are the same size, then yes it would be going at half engine speed as the at the other end the camshaft pulley is twice the size of the crankshaft and has exactly twice the amount of teeth, so the camshaft turns at exactly half engine speed which is of course crankshaft speed.
Will have a play with those figures and see what crops up.
Dave
Will have a play with those figures and see what crops up.
Dave
Dave.
I seem to remember someone, probably Anders giving some calculated drive speeds derived from relative pulley sizes. The surprising thing was that the 16 valve pump went fastest of all.
I agree that the camshaft pulley will revolve at half engine speed, but I'm sure my TD has a larger pulley on the pump than on the camshaft providing a further reduction. Looks as though I will have to try and measure the diameters - should be fun without taking anything to bits!
Jeremy
I seem to remember someone, probably Anders giving some calculated drive speeds derived from relative pulley sizes. The surprising thing was that the 16 valve pump went fastest of all.
I agree that the camshaft pulley will revolve at half engine speed, but I'm sure my TD has a larger pulley on the pump than on the camshaft providing a further reduction. Looks as though I will have to try and measure the diameters - should be fun without taking anything to bits!
Jeremy
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Dave Burns
- Posts: 1915
- Joined: 14 May 2001, 05:30
- Location: United Kingdom
- My Cars:
- x 2
Found some info on the 6+2 pump, the 6 pistons for the steering provide 3cc per revolution and the two pistons for the brakes and suspension provide 1cc per revolution.
On the TD the pump pulley is 108mm, the crankshaft pulley driving it is 152mm so this gives a ratio of 1=1.4
At engine Idle of 950 rpm the pump is doing 1330 rpm, with a 1cc per rev output that gives 1330cc per minute, divided by 60 for 22.16cc per second.
Since it takes about 125cc of oil to increase the sphere pressure to the 90 bar required for the s/valve and stop light, 125/22.16 gives a light out time of 5.6 seconds from rest, or at idle speed of 850 rpm, 6.3 seconds, my papap with good sphere's and hydraulics is in that range so it would seem to be a reasonably accurate.
A BX with a 4cc pump driven at half engine speed I calculate to be about 4 and 4.5 seconds for idle speeds of 950 and 850 rpm respectively.
Dave
On the TD the pump pulley is 108mm, the crankshaft pulley driving it is 152mm so this gives a ratio of 1=1.4
At engine Idle of 950 rpm the pump is doing 1330 rpm, with a 1cc per rev output that gives 1330cc per minute, divided by 60 for 22.16cc per second.
Since it takes about 125cc of oil to increase the sphere pressure to the 90 bar required for the s/valve and stop light, 125/22.16 gives a light out time of 5.6 seconds from rest, or at idle speed of 850 rpm, 6.3 seconds, my papap with good sphere's and hydraulics is in that range so it would seem to be a reasonably accurate.
A BX with a 4cc pump driven at half engine speed I calculate to be about 4 and 4.5 seconds for idle speeds of 950 and 850 rpm respectively.
Dave