Hello there from sunny Suffolk. We have an old but much loved Fiat Uno 45s and I thought that you might be able to help us with a weird problem we have with the brakes, that is sometimes they work and sometimes they don't. I think it might be the servo, I've cleaned the white one way valve that go's into the servo but I'am not sure what to try next. I would be grateful for any advice you can give me.

Honey Monster said:

Hello there from sunny Suffolk. We have an old but much loved Fiat Uno 45s and I thought that you might be able to help us with a weird problem we have with the brakes, that is sometimes they work and sometimes they don't. I think it might be the servo, I've cleaned the white one way valve that go's into the servo but I'am not sure what to try next. I would be grateful for any advice you can give me.

Click to expand...

Hi. Do you mean they are not as good on some occasions..lack of servo assistance.

Or just fail in some way.

AFAIK. The white 90' elbox is the vacuum joint from manifold to servo..Ive still got a new one from my tipo..

Charlie . Oxford

The brakes if they fail do so at or near tick over, they don't fail completely you just have push really hard to stop. So it's probably something to do with the servo as you said.

Honey Monster said:

The brakes if they fail do so at or near tick over, they don't fail completely you just have push really hard to stop. So it's probably something to do with the servo as you said.

Click to expand...

Hi,
That is a vacuum servo issue. Either the diaphram in the servo (the drum shaped bit) is leaking or it is not getting the vacuum from the engine. To check the one way valve (normally in the elbow fitting as you say) sit in th car with the engine off and pump the clutch pedal until it goes hard. With your foot still pressing (not hard) on the brake pedal, start the engine without revving it. The pedal should go down slightly as the vacuum builds. If it does not go down rev the engine gently. If the pedal suddenly goes down the valve is sticking, buy a new one (and the rubber grommet it fits into).
If OK, take foot off brake, rev the engine for a minute to build vacuum, idle and then switch off engine without touching brake. Leave overnight and in the moring pump brakes with engine off. It it is hard immediately you almost certainly have a servo leak. If it goes hard after one or two presses, the servo is OK. In this case (good servo) look for a leak in the pipework to the manifold or the manifold itself.
My bet is a sticking valve or servo. Note you don't have to change the master cylinder, just the servo.

HTH,
Robert G8RPI.

Thanks for that, can you recommend any suppliers for Fiat Uno parts?

Honey Monster said:

Thanks for that, can you recommend any suppliers for Fiat Uno parts?

Click to expand...

try shop4parts, forum supporter

or Ebay - as some parts will be listed as clearance - and really cheap