Brake failure on Saxo.

[Citroenmad]

We have been looking after a family friends Saxo for a while now, doing services and repairs etc.

Its a 2001 Y reg 1.1i Saxo Desire with 96K miles - owner has had it from new and its a very tidy example and well cared for.

After replacing the front wishbones this weekend, i took it for a short test drive. I then parked it on the drive, it drove fine and the brakes worked perfectly. The next time i went to it to take it back to its owner i reversed off the drive but there was no brakes, the pedal just went straight to the floor without slowing down any.

I got out to find brake fluid pouring from the rear brake. The cylinder is leaking, so ive got two cylinders and a set of brake shoes on order.

However, i would have thought it should have a secondry braking system? So all brakes are not lost if a failure like this should happen.

Im extrmely pleased it decided to give up just as i was getting it out of the drive and not when it was being driven on the road, no doubt it would have caused an accident.

The lady owner does quite a few miles in it for work and its quite concerning that this kind of sudden total brake failure should happen.

I might add that nothing we have ever done to it has effected the brakes.

Should this Saxo have a secondary brake line/system to stop a total failute like this? I would have thought so.

[spider]

They are as far as I know a dual circuit master cylinder (two pistons) and I think the resovouir (sp? I can never ever remember how to spell that word) is split internally too, so if one circuit has failed you should be able to pump the brakes up to get some emergency braking.

I'd have to say the other cylinder must of been leaking for a while too (not the exploded one) , you`ll probably see its made a mess on the shoes on that side too...

[Chris570]

yeah its a diagnoal split as on most cars, i've had this on a 106 before, and it had brakes but they were way way way down the bottom of the pedal.

[Citroenmad]

This one doesnt have any brakes as far as i can tell. I pumped the pedal a few times at first but nothing It just spits loads of fluid out of the rear brake.

Ive just removed the drum on the leaking side and its pouring out of the piston. Ill remove the other side later ready to fit the new bits. I wonder if that will be leaking too, spider.

The parts should be here tomorrow, both pistons and shoes.

Its owner isnt too pleased with it at the moment, as it seems to be one thing going after another.

The radiator went while we were on holiday, so she had to get someone else to fit it. Ive no idea what they have put in the cooling system, but it doesnt look like antifreeze to me. I put my finger in with a latex glove on and it shriveled the glove up. It smells odd and when the car is left parked the water at the top of the header tank becomes gloopy and thick, like a gell. I had first thought it was HG but it doesnt seem to be.

While fitting the wishbones you have to have the carpets up in the front of the car. On the passenger side the footwell is very wet, but its this gloopy thick gell stuff again. Looks like the heater matrix is leaking. Maybe as a result of this solvent stuff which has been added. Hopefully a coolent flush, new coolent and radiator stop leak will fix it. Though im not doing it, the person who fitted it can.

Shame, as its a nice little car. I love driving Saxos too, great little cars in my opinion. Its always nice to see how well they stand up to the weather. Its got no rust at all, apart from a slight bit in the usual place under the bonnet. A Yreg Fiesta however will be fizzing in the rain by now!

[spider]

The gel stuff you found in the coolant is probably remnants of the leak fix that was (maybe?) used to 'cure' the heater matrix.

Never done one on a 106 or Saxo, to be honest failure of a heater matrix on these seems really rare. I saw a 205 one done without dash removal (pedals half removed and dash partly dismantled for access) but that's off topic. I've never seen one fail on a 106 anyway.

I bet the other cylinder will be on its way or leaking. The theory with split circuits being as the resoviour is split too, you cannot loose all the fluid so one piston will still work.

Its possible (and they are a bit um poor sometimes) the rear brakes are well out of adjustment anyway which would not help as with just one circuit working fluid would always go the easiest route...

New cylinders and shoes, adjust them up nicely (annoying if they have the 'teeth at the bottom' adjuster ) and all should be good braking wise.

[Chris570]

dash removal on a saxo /106/ax isnt that hard, just long really, get your 10mm and 13mm spanner ready

[JohnD]

However, i would have thought it should have a secondry braking system?

Should this Saxo have a secondary brake line/system to stop a total failute like this? I would have thought so.

I would have thought it would have. Mine certainly has and it's a 1998 model. Open the fluid reservoir and the divider is just below the filler cap.

Recently I fitted new cables to the rear drums on our 306 prior to MOT. Although there was no signs of leaking fluid, I peeled back the cylinder boots and there was signs of dampness, so in due course a couple of new cylinders will go on order.

[Citroenmad]

Well the parts should be here today hopefully. Boths sides will have new cylinders as the other one is likely on its way out too.

The owner said the car has never had a leak inside the car before or any head gasket problems. It had a new radiator as it was leaking but was fixed with a new one and not some kind of rad stop. So im not sure what that gloopy stuff is, certainly doesnt look or smell like coolent.

[RichardW]

There are rumours that if you add 'old' style coolant to a car 'fitted' with modern long life OAT stuff, then it can cause a reaction that turns the coolant to jelly. Never seen it, but it sounds like you might have! Seems like it will need a drain, thorough flush, and refill with the correct coolant. I'd be making a strong case to the garage that did it that it caused the matrix to fail as well, and they should stump up for that. Some hope I guess....!

I've never understood the diagonal split systems either - in cases where I've have brake failure (a couple of times in a Visa which had a sticking brake that boiled the fluid, and in a ZX when it popped a rear cylinder) it's been foot to the floor with nothing. Can't really understand how it is supposed to work.....

[Citroenmad]

Im pretty sure its somehting has been put in the coolent when its had a new radiator. Possibly the new style coolent.

The owner is going to take it back to the garage who did it and see what they say. At the very least its up to them to flush, drain and refill the coolent system with the correct coolent.

As for the heater matrix, im pretty sure thats whats leaking, and its possible that the contaminated coolent has had an effect on that. Though im not sure how that would be proven.

The owner was hoping to scrap the car for a new one under the scrappage scheme. Though obviously it was too new (Y reg). She wants the car to last a year and then is going to get rid for a new car.

Im hoping some Forte Radiator stop leak will cure the problem, at least for the next year. Ive cured mild headgasket problems with it before, so it might do the trick. If not it will have to have a matrix.

Its a poor system if total brake failure is allowed, id not like to think what could have happened had it gone on the road, could have been very nasty.

[myglaren]

I've never understood the diagonal split systems either - in cases where I've have brake failure (a couple of times in a Visa which had a sticking brake that boiled the fluid, and in a ZX when it popped a rear cylinder) it's been foot to the floor with nothing. Can't really understand how it is supposed to work.....

Had a brake failure on a Volvo 265 and the only noticeable effect was the glare from the warning light on the dash.
Fixed the leak but re balancing the split system was a lengthy task to say the least.

[Kowalski]

I've never understood the diagonal split systems either - in cases where I've have brake failure (a couple of times in a Visa which had a sticking brake that boiled the fluid, and in a ZX when it popped a rear cylinder) it's been foot to the floor with nothing. Can't really understand how it is supposed to work.....

The diagonal split is supposed to do two things:

1) It means if you lose one brake circuit it only affects one side of the car, i.e. the car won't be steered by the brakes as much as it would if it was a left / right side split.
2)It means if you lose one brake circuit, you don't lose the both of the powerful front brakes and have to rely on the weedy rear ones.

The XM and Xantia have a front / rear split, that was the reason that the handbrake worked on the front brakes instead of the rear.

[Citroenmad]

Well we have got it put back together now and the brakes working ... the cylinder was not leaking.

It seems to have been a slight design fault. What had happened was the friction material had become unbonded from the metal backing plate. The friction lining had then slipped to the bottom of the drum meaning the piston had to push out more to get contact with the inside drum face.

The piston is very very short and does not have the required movement to allow the backing metal plate to touch the inside of the drum. So the end had popped off the piston and fluid was leaking.

The seals are all good, no wear or scoring marks and when reasembled with new brake shoes there is no leak and the brakes are working fine again.

Our C15 did the same thing, the friction plate fell off the brake shoes, however as the piston is longer it didnt cause a leak.

Seems to be a bad idea on the Saxo.