Slow servo build up cdti

[2.2-600-vtec]

Well changed the servo, and well no real diffrence, the system holds the vac ok but the brakes are next to useless, the pedal moves all ok, but the car does not stop in any real urgency,
pads and discs look ok, but i am going to replace all the disc and pads, and maybe flush the fluid as well,

On a plus note, the plenums where fully blocked both sides so flushed them out no ecu issues anyway but did need to be done, also pollon filter was extreamly blocked, yet its only just over due its next service, with full history, so maybe brakes have never been flushed??

Still doing the servo was not to bad to do just time consuming.

[Arctic]

Hi Nathan
Did/have you checked all the braided pipes from the EGR solenoid backwards as I have know then to chafe and become holed few pics below, maybe worth a look and re-routing it cheers Arctic

[2.2-600-vtec]

Hi thanks for the reply, but my egr is blanked at the outlet from the non return valve on the main vac pipe, the rest of the pipe draws a solid vac when I tested it.

Its a strange one,

[HarryM1BYT]

Originally Posted by andrewinpopayan

Vacuum should build up really quickly, no more than a couple of seconds AND stay there for a good while when you stop the engine.

Andrew

As a point of reference...

Mine will hold the vacuum for many days, maybe even weeks. I can go back to it after its been stood and get 2 maybe 3 presses before the stored vacuum is exhausted and the pedal goes hard.

Vacuum is only fed to the EGR and its pipe, at low engine revs and via a solenoid operated valve, controlled by the ECU.

If assistance is poor, but only at low speeds, then I might be inclined to blame it on a leak via the EGR part of the system - the solenoid, the EGR pipe, the EGR if fitted.

[David Lawrence]

Originally Posted by HarryM1BYT

As a point of reference...

Mine will hold the vacuum for many days, maybe even weeks. I can go back to it after its been stood and get 2 maybe 3 presses before the stored vacuum is exhausted and the pedal goes hard.

Vacuum is only fed to the EGR and its pipe, at low engine revs and via a solenoid operated valve, controlled by the ECU.

If assistance is poor, but only at low speeds, then I might be inclined to blame it on a leak via the EGR part of the system - the solenoid, the EGR pipe, the EGR if fitted.

i have a vacuum brake bleed tool with a vacuum meter attached to it, and it recorded 760mmhg when i checked mine which at the time was regarded as about what it should be. One difference we established between Harry and me was that his vacuum did not exhaust until 4 pumps where mine exhausts after 2.5 presses.

Never really got to the bottom of it. However, i now have a second car to compare it with, as i bought a cdt auto about 6 weeks ago. Without a doubt the brakes are much sharper and firmer on this one, but also notice with vacuum fully exhausted the auto pedal moves only about 1" before it goes solid, where the older manual car will go maybe 1.5". I guess if the pedal moves further then it will use more vacuume in the process.

This leads me now to reconsider if I might have air trapped in my ABS module from way back when i replaced the front to rear brake pipes.

probably the only way to find out for certain is going to be to do a T4 bleed session which can operate the ABS pump during bleeding.

As the manual car is shortly due for some major refurbishments on suspension, brakes etc, then I will wait until then, but you might want to consider if air in your Abs module is a possibility for you.

[2.2-600-vtec]

Originally Posted by David Lawrence

i have a vacuum brake bleed tool with a vacuum meter attached to it, and it recorded 760mmhg when i checked mine which at the time was regarded as about what it should be.

HI 760mmhg?? i read that it should only be 300mmhg approx -1bar or 0bar absolute.

Mine was reading on the old servo 300mmhg or am i reading it wrong, as i used a boost pressure gauge as it read vac?

I feel that there is air in my system as it does have the sinking pedal syndrome, but i think a good snap on modis is supposed to be able to do a electronic brake bleed??

Thanks
Nathan

[HarryM1BYT]

Originally Posted by 2.2-600-vtec

HI 760mmhg?? i read that it should only be 300mmhg approx -1bar or 0bar absolute.

Mine was reading on the old servo 300mmhg or am i reading it wrong, as i used a boost pressure gauge as it read vac?

I feel that there is air in my system as it does have the sinking pedal syndrome, but i think a good snap on modis is supposed to be able to do a electronic brake bleed??

Thanks
Nathan

I think I will be correct in suggesting that no one found a cause for the sinking pedal syndrome, you either have it or not and its not a problem come MOT time, providing the sinking is not too rapid.

[2.2-600-vtec]

I had a sinking pedal on a zs with big brake conversion and had that done on a t4 and pedal was rock solid superb pedal so much more control and power. so maybe similar on the zt??

[andrewinpopayan]

Originally Posted by 2.2-600-vtec

HI 760mmhg?? i read that it should only be 300mmhg approx -1bar or 0bar absolute.

Mine was reading on the old servo 300mmhg or am i reading it wrong, as i used a boost pressure gauge as it read vac?

I feel that there is air in my system as it does have the sinking pedal syndrome, but i think a good snap on modis is supposed to be able to do a electronic brake bleed??

Thanks
Nathan

760mM/Hg is 1 atmosphere, so nothing wrong there.