PWDA information

[PimentoRed]

Afternoon gents

I have searched the threads on this and can't find the specific answer so I hope one of you could shed some light please?

Just replaced servo and brake master cylinder for new kit. Old ones had leaked over inside of engine bay so thought best to get new ones.

I spent an hour trying to bleed brakes last evening. Drivers side rear 1st, little fluid coming out. Passenger side rear, small amount of fluid coming out.

Have not attempted fronts yet.

Pedal travels completely to floor, fluid is to top of dividing vane in brake fluid chamber. Topped up to replace small fluid released from passenger side rear.

Questions are, do you think that the PWDA switch has activated? Assuming that would stop the fluid flow? If so how do I re set it?

Should I bleed front brakes before checking PWDA?

I have limited technical ability so please be specific lol

Thanks in advance

Mike

[Stocky]

Firstly, how are you bleeding the brakes (using an EaziBleed type device or two person)? Jam jar half filled with brake fluid with the bleed tube under the fluid level?
Secondly, to check the PDWA: unscrew the plastic electric connector (no fluid should escape; if it does, you will need to remove the PDWA and renew the seals) and insert a small jewellers screwdriver. If you move this from side to side you should find the groove in the centre of the shuttle; this should be centred and if not, it is possible to centre it using the screwdriver.

[PimentoRed]

Hi Stocky

I'm using the Europat Vizibleed one man kit from Halfords with a non return valve. Do I need to submerge end in brake fluid?

I will try that on the switch, thank you.

Mike

[Stocky]

Non-return valve so no need to submerge the bleed tube.
I assume that the pedal goes to the floor as there is air in the front brake lines, so you are compressing this.

[DJT]

If you take a look at the photos in my albums, there is a picture of the tool I made a while back to keep the PDWA shuttle in the centre when bleeding the brakes. Just remove the nylon switch and insert this tool finger tight, having first confirmed that the shuttle is centred.

[72BLUE]

If you take a look at the photos in my albums, there is a picture of the tool I made a while back to keep the PDWA shuttle in the centre when bleeding the brakes. Just remove the nylon switch and insert this tool finger tight, having first confirmed that the shuttle is centred.

I wondered about centering the shuttle when I bled my brakes with an ezibleed recently. However, I tried without bothering and all was fine. After the bleeding was done, I did have to centre the shuttle which was easily done with a 1.5MM drill. Shortly after, the MOT readings for my brakes were very high.

Cheers
Keith

[Andrew S]

Just out of interest, if you don't lock the shuttle and bleed the brakes say at the back, then do the front, is there a chance that the shuttle will allow more flow to bleed them better if allowed to move either way? Then centre the shuttle afterwards.

[PimentoRed]

Hi Guys

Thanks for the comments. It is probably me but I took the nylon bolt out and inserted a very small screwdriver, i didn't know really what I was feeling for but nothing moved so do I assume that nothing needs to be centred?

They make it look so easy in the manuals and on the bleeding kit box.

Mike

[DJT]

I wondered about centering the shuttle when I bled my brakes with an ezibleed recently. However, I tried without bothering and all was fine. After the bleeding was done, I did have to centre the shuttle which was easily done with a 1.5MM drill. Shortly after, the MOT readings for my brakes were very high.

Cheers
Keith

Hi Keith,

Yep. Sometimes it works fine, sometimes the shuttle gets displaced, then it is either try and reset it with a screwdriver or by bleeding the other circuit. I now find that this gadget takes all the effort out of the job.

[72BLUE]

.....It is probably me but I took the nylon bolt out and inserted a very small screwdriver, i didn't know really what I was feeling for but nothing moved so do I assume that nothing needs to be centred? Mike

If you use the smooth end of a 1.5m drill bit, you can easily 'feel' the profile of the shuttle and centre it if needed with the same drill bit.

Keith

[PimentoRed]

Cheers Keith

I'll give it another go tomorrow, it's suddenly gone very dark in the Cotswolds.

Mike

[Stocky]

Hi Guys

Thanks for the comments. It is probably me but I took the nylon bolt out and inserted a very small screwdriver, i didn't know really what I was feeling for but nothing moved so do I assume that nothing needs to be centred?

They make it look so easy in the manuals and on the bleeding kit box.

Mike

Imagine that the shuttle is a piece of round iron bar with a v shaped groove cut around the circumference at the mid-point. Now move your screwdriver left to right along the bar; you will feel the driver dip into the groove.
Now do this through the hole in the PDWA. You will need to angle the screwdriver as far as you can to one side then scrape it along the shuttle. You will feel the grove at some point.

[72BLUE]

Hi Keith........ I now find that this gadget takes all the effort out of the job.

I agree Dave, it is something that I will possibly get around to making one day.

Just a thought, I was able to move my shuttle fairly easily but do they ever sieze up? I know the seals can leak, but can the shuttle sieze and not leak, giving a sense of false security as the brake warning light would never work if one of the circuits developed a leak.

Cheers
Keith

[PimentoRed]

Imagine that the shuttle is a piece of round iron bar with a v shaped groove cut around the circumference at the mid-point. Now move your screwdriver left to right along the bar; you will feel the driver dip into the groove. Now do this through the hole in the PDWA. You will need to angle the screwdriver as far as you can to one side then scrape it along the shuttle. You will feel the grove at some point.

Stocky I think that that is what I felt, directly in the centre of the hole. Maybe it is centred. I thought it may be off as there was so little fluid coming out when bleeding each wheel. Do you think I should bleed the fronts and see if the pedal hardens off?

Sounds like a plan

[72BLUE]

Hi Mike, ha ha! I have had a doodle in paint! See attached pic, but please be aware that it is all way out of scale and proportion etc, hopefully you will get the idea

Keith


Shuttle valve.jpg