Failed MOT - Advice needed

[froggy]

Finally got to the MOT station today and it failed, nothing serious i hope but thats where you (hopefully) can help.

Reasons for Failure
1. Nearside Front headlamp aim to low (Not really an issue)
2. Nearside rear reflector not red in colour (Not an issue just need new lense)
3. Offside rear reflector not red in colour (as above)
4. Nearside rear position lamps affected by operation of another lamp (fitted bulbs wrongway round)
5. Offside rear position lamps affected by operation of another lamp (fitted bulbs wrongway round)

NOW THE ONES I NEED HELP WITH
6. Nearside rear brake recording little or no effect
7. Service brake efficiency below requirements **DANGEROUS**

Spoke to the tester (also a VW fan) he thinks it might be either the servo or the pipes to the servo leaking leading to poor brakes and possibly a new wheel cylinder for the nearside brake readings.

 

[Araon]

Offside ok then

try the regulator....
non return valve in the servo line

 

[froggy]

Offside ok then

Offside worked but still not to the spec.
With all brake readings down this is why the tester thought it might be the servo

 

[froggy]

Where is the non return valve in the servo line located?
Know where i can get some new servo hose from or what size it is?

 

[Clarkson46]

Why would the servo only affect one rear brake? This IMHO is a red herring. Check the wheel cylinder for leaks, check the flexible pipe to that wheel for collapse. It much more likely to be something directly related to that wheel.

 

[froggy]

There are 2 faults with the brakes,
the 1st being little or no effort on the rear and the 2nd fault being all round poor effeicency
Its because of the second fault that the tester beleives the servo might be at fault

 

[ronmidg]

is there a difference on the duff rear brake depending on whether it is hand brake or foot brake? a leaky slave cylinder/drenched shoes will give about 25% of the brake effort compared with the good side, if its all dry then a good foot brake/bad handbrake on one side is likely the cable seized on that side, if its bad foot brake/good handbrake on one side its likely a stuck slave cylinder.

 

[froggy]

if its bad foot brake/good handbrake on one side its likely a stuck slave cylinder.

Going to change the wheel cylinder on the duff side

 

[froggy]

Managed to get hold of some rubber pipe today from work (re-inforced Pirtek hose) and changed all the servo hoses from front to back, well carb manifold to non-return valve, non-return valve to metal pipe running under the van and then from this pipe to the servo its self.
Had to buy some pipe from a local hydralics place to go from the front of the servo to the pipe that goes through the driver wheel arch (any idea what this is and where does it go?)
Drove the bay up the road and the difference is amazing, the brakes very feel responsive compared to before.
Just the rear cylinder to replace and then re-test.
Can finally see the light at the end of the tunnel 8) 8)

 

[Trikky2]

from the front of the servo to the pipe that goes through the driver wheel arch (any idea what this is and where does it go?)
8)

Glad to hear its better now.

The pipe is the breather for the servo and just goes into the body section to avoid dust and water getting in. Most moderns just have a little filter instead. The pipe into the body was fitted because th servo on a bay is quite low and could have problems when fording rivers or going through flood water. (One of the many reasons they were reliable and hence popular in the third world).

Its not imperative but normally , when I change cylinders I do both sides since if one failed the other is probably close to the end of its life btw.