Technical Brake pedal very hard to press

[Westies on tour]

Morning all please help.

My fiat 500s 66 plate 1.2cc when I got in the car this morning the first 2 or 3 times I hit the brake pedal it was OK, after that it was hard to push.

This was at 06.00 this morning on my way to work, I'm now at work posting this to you guys.

Whats wrong please?

It's it cause of the cold weather-3 degrees something frozen?

Got to work safely but I'm worried it might be the same driving home later today.

 

[John202020]

If the brakes seem to work as they should, but , its very hard to press the pedal, first check if any mats are obstructing the pedal, look on passenger side too, from what you've said I would guess a lack of servo assistance, it would be unusual on a car that's not that old I have to say.

 

[mj2k]

Only other thing I could think is if the brake discs got wet somehow and a layer of ice froze over them, but you'd have to try pretty hard to do that...

When were the brake pads last replaced? How about the brake fluid?

 

[Pugglt Auld Jock]

Easy to check the servo is working. Sit in the car and without staring the engine push the brake pedal up and down half a dozen times. This will evacuate any stored vacuum from the system. Now, still without starting the engine, push down firmly on the brake pedal and, holding that pressure constant on the pedal, now start the engine. If the servo is working you should feel the brake pedal pull down slightly under your foot. Some setups pull down more strongly than others but I've not tried one yet that you couldn't feel this effect. If it doesn't pull down then the servo isn't working.

Your description that the servo seemed to have worked for the first couple of applications but then the pedal went "hard" would seem to me to say that the servo was working on residual vacuum left over from the last time you drove it. There is a wee sort of "shuttle" valve inside the servo which is the first thing to move when you press down on the pedal and it's this valve which allows vacuum to act on the diaphragm. I suppose it's just possible that this valve may have frozen overnight - last night was apparently the coldest this year - so I'd wait until the day warms up a bit, maybe run the heater too? and try it again. If it "miraculously" starts to work properly when the frost goes away then I'd be taking bets on it being that valve. If it's still not working when it warms up a little then the servo pipes and connections would be your next place to look.

Do please let us know how it turns out?

 

[Westies on tour]

I finish work at 4pm so will try then thank you all.

 

[Westies on tour]

Hi all thank you all for your input.

When I got to my car at 4.05 pm I done as suggested in above post and all was working as normal.

I tested the brake pedal several times and seamed to be ok.

Maybe as I thought frozen?.

Anyway all good and ok.

 

[mj2k]

Hope it's not the brake fluid which froze (it absorbs water) otherwise it'll be urgent time for a brake fluid replacement

 

[vexorg]

I think he means the valve to the vacuum servo....

Very unusual either way.

 

[Pugglt Auld Jock]

Glad to hear all seems Ok again. It'll be interesting to hear whether it does it again if we get another very cold day?

 

[chris3234]

Hope it's not the brake fluid which froze (it absorbs water) otherwise it'll be urgent time for a brake fluid replacement

Extremely unlikely you'd have to have a very high water content in the fluid for it to freeze unless your in artic conditions even they it would take a lot of water



For it to freeze in the UK winter you'd would need so much water in the fluid your brakes wouldn't work right most of the time and you'd definitely feel in the the braking

 

[mj2k]

Extremely unlikely you'd have to have a very high water content in the fluid for it to freeze unless your in artic conditions even they it would take a lot of water



For it to freeze in the UK winter you'd would need so much water in the fluid your brakes wouldn't work right most of the time and you'd definitely feel in the the braking

True enough, it'd be a scary thought though if there was so much water it did freeze...

 

[jrkitching]

True enough, it'd be a scary thought though if there was so much water it did freeze...

Essentially impossible. Brake fluid is a glycol ester, mutually soluble in water, so basically neat antifreeze. Freezing point is around -40, and even at that temperature, it'll just turn very viscous, rather than solidifying. Any water contamination will stay in solution; it won't freeze out separately.

The exceptions are the mineral and silicone based brake fluids used in some citroens and race cars; these won't hold water in solution, which makes water contamination much more serious with these types of fluids. Not so much because of freezing, but because of corrosion. If it's in solution (as with normal brake fluid), it can be inhibited; not so easy if it's separated out.

 

[John202020]

It's possible there was water vapour in the pipe to the servo ? Blocking it?

 

[vexorg]

The vacuum should suck it out into the inlet