Technical Seicento MPI 2002. Total brake failure, help needed

dx90 · Oct 8, 2016

More brake problems.

A few weeks ago I had the rear brakes bind and over heat.

The hand brake cable was the problem. I also took the opportunity to clean up, new shoes and re-grease where needed. Problem fixed.

Last night the car had 4 people in it and I drove to get some take out. The car was driven at 30 mph on local roads.

On the way back the brakes started to smell and when I tried to stop the car the brake pedal went straight to the floor. I tried them again and had just enough brake to stop the car. I drove a short distance to find a safe parking place and tried the brakes another 4 or 5 times and still the pedal went to the floor with no brakes.

I got out the car and felt for heat from the rear wheels and they were smoking hot but so were the front ones this time. They were hot enough that I couldn't keep my hand on the wheels.

I left the car until all 4 wheels had cooled down enough for me to touch them and re-tested the brakes again and they were back to normal. Firm not spongy. I drove it around the block and the brakes were back to normal.

I parked the car up for a couple of hours and tested the brakes again and all was fine.

I drove back home with no brake problems. I tested them this morning and still normal.

What would cause this dangerous fault?

Thanks

The Black Box · Oct 8, 2016

Did you renew/free off the handbrake actuators. They should be free enough that you can flick them. Another thought how old is the brake fluid?

dx90 · Oct 8, 2016

Yes the actuators were free. If you mean the one that connects from the cable to the shoes. That doesn't explain about the front disks overheating.

The handbrake cable was adjusted to be fully on at 6 clicks and both wheels were free running when handbrake was off. I did this to let the cable settle in before final adjustment but this happened before I could do it.

The brake fluid is very dark in colour. I asked my local garage to do a full brake fluid change at the same time they were fitting a new metal brake pipe. They said there was no point because they had temperature tested it and it passed the test.

dx90 · Oct 8, 2016

The fluid looked very dark, looking down in but after I put some on a white cloth the colour is more a slightly dirty white but not the yellow colour I have here. It's defiantly not been changed in the last 6 or so years that the car has been in the family.

I will change the brake fluid today anyway. Do I have to push the the calipers all the way in on each wheel first or is it it OK to just open the nipple and bleed?

I'm going to use a hand pumped pressure bleeder on the reservoir but will be refilling the reservoir after each wheel is bleed. Do you know the max pressure I can use?

Thanks

dx90 · Oct 8, 2016

varesecrazy · Oct 8, 2016

routing looks reasonable ( not an expert) - better then your silencer bungee..

I found trawling through the pics awkward..( "arrows" showed me twin-cam ,and a rusty catalyst..) far easier on the forums hosting

as rob said , get the fluid flushed, changed and bled,
no you don't need to move any pistons,
give the bleed nipples a good soak in plusgas though.., as they are a nightmare if they shear off.

Charlie

The Black Box · Oct 8, 2016

Definitely get the fluid changed should be done every 3 years! Would be worth a check to see if the front pistons moves ok. Something's obviously getting hot and expanding old fluid wouldn't help here.

Worth a check on all hoses especially pay attention to behind the front plastic inner arches where the flexi hose joins the rigid. These rarely get checked and I've had several snap the metal pipes here resulting in interesting braking

dx90 · Oct 10, 2016

Just an update. Did a full brake fluid flush and bleed all the brake. NS/R, OS/F, OS/R, NS/F. I read some where that this was the correct order. Hopefully it is.

The problem I had with the bleeding was that the OS/R had no fluid coming out at 15psi. I tried twice and I was even able to take the nipple out and still no fluid. I then put 20psi of pressure through and there was the slightest little trickle and then it stopped. So I got a rubber mallet gave the drum a few good thumps and it cleared the blockage. It must of got so hot that it baked and blocked it up.

The car has always 99.9% of the time first thing in the morning when the foot brake was first applied, thumped through the peddle and you could hear it as well. It felt like it was sticking. It has been like that for years. I did a search on it loads of times. I found others with the same problem but no one found a cure.

The last two mornings after changing the brake fluid there has been no thump and the brake feels smooth and progressive now. A huge improvement. The difference is like day and night.

The front callipers are moving fine.

Time will tell if it has fixed the problem. If not I suppose I should put new cylinders in next. What do you think?

rallycinq · Oct 10, 2016

Sometimes a flexible pipe can delaminate inside leading to an NRV effect.

D

dx90 · Oct 10, 2016

rallycinq said:
Sometimes a flexible pipe can delaminate inside leading to an NRV effect.

D

Is there anyway of finding out if that is happening?

rallycinq · Oct 10, 2016

dx90 said:
Is there anyway of finding out if that is happening?

Hot brakes.....

D

dx90 · Oct 11, 2016

rallycinq said:
Sometimes a flexible pipe can delaminate inside leading to an NRV effect.

D

Never heard of this before, so I had a good read up. Very interesting how often the inner hose separates from the outer hose to cause a Non Return Valve effect.

I won't rule it out, but I don't think it applies to the brake problems I have. For both sides to bind at the exact same time through de-lamination seems unlikely. Then again so does both cylinders seizing at the same time.

When I bled the OS/R no fluid came out. The wheel was also free moving at that point. I think the fluid had so much moisture in it that it boiled and caused it to block in the cylinder just behind where the nipple goes in.

I have changed the the handbrake cable, cleaned and lubricated where needed and all parts are moving freely. I changed the brake fluid with some new ATE SL6. I have left the handbrake cable under adjusted for now to rule that out.

I think if both back brakes bind again at the same time I will change both cylinders and see if that does the trick. I'm hoping that the old fluid was the cause of the problem. Fingers crossed.

Thanks

rallycinq · Oct 11, 2016

I wonder if the load valve got humpty...you said you were 4 up.

D

varesecrazy · Oct 11, 2016

I suspect it had somehow got AIR in the cylinder instead of fluid..,

the air will compress enough to give basic braking effect..but obviously EXPAND a lot when HOT so would explain your binding..,

I suspect your pressure flushing will have done the trick..

I had a similar dry effect on a hydraulic clutch.. took 60 PSI to get fluid through it..

worked fine after though..

hopefully you'll now be fine,

Charlie

dx90 · Oct 11, 2016

rallycinq said:
I wonder if the load valve got humpty...you said you were 4 up.

D

Load valve. What is that?

varesecrazy, I hope it works as well.

Thanks

dx90 · Oct 11, 2016

rallycinq said:
I wonder if the load valve got humpty...you said you were 4 up.

D

I have looked up what it is but can you tell me if there are any on the Seicento Sporting 2002 and where are they and what do they look like?

Thanks

rallycinq · Oct 12, 2016

On yours its a proportioning valve only. Do you have ABS? Mine has the brakes split front and rear a twin master cylinders, unlike most other centos.

Cheers

D

dx90 · Oct 12, 2016

rallycinq said:
On yours its a proportioning valve only. Do you have ABS? Mine has the brakes split front and rear a twin master cylinders, unlike most other centos.

Cheers

D

Thanks for replying. I don't have ABS on mine.

Metalguru3 · Oct 12, 2016

Hi
I've had quite a few cars come into the workshop over the years with blocked brake hoses.

If you cant push fluid through an open nipple with the foot pedal chances are the hose is blocked. Don't know whether its coincidence but most were volvos if I remember right.

My sei has had overheated rear brakes, but only when I over adjusted them to get the handbrake really sharp. I leave a couple of clicks on the ratchet now, and still get a decent handbrake.

The trick is to not over adjust the shoes by levering them too tight against the drum using Fiat's unique "self adjusting" mechanism - barely making contact is enough. If in doubt push them back to their minimum setting and start again if you want to get the best setup. I always bash the drum with a hammer a few times before refitting the wheel to make sure they arent set too tight

Old fluid boils easily as it has absorbed water from the atmosphere, creating vapour voids leading to no brake pedal. After everything cools down, the vapour condenses back into fluid the the pedal returns.

On a recent classic run, my moggie boiled the brake fluid on the way down the Long Mynd in Shropshire - really terrifying, especially for the drivers coming back up the hill against me but a quick stop in the hotel at the bottom and everything was ok again - needless to say I changed the fluid, and it hasn't happened since.

hope you get them sorted

dx90 · Oct 13, 2016

Metalguru3 said:
Hi
I've had quite a few cars come into the workshop over the years with blocked brake hoses.

If you cant push fluid through an open nipple with the foot pedal chances are the hose is blocked. Don't know whether its coincidence but most were volvos if I remember right.

My sei has had overheated rear brakes, but only when I over adjusted them to get the handbrake really sharp. I leave a couple of clicks on the ratchet now, and still get a decent handbrake.

The trick is to not over adjust the shoes by levering them too tight against the drum using Fiat's unique "self adjusting" mechanism - barely making contact is enough. If in doubt push them back to their minimum setting and start again if you want to get the best setup. I always bash the drum with a hammer a few times before refitting the wheel to make sure they arent set too tight

Old fluid boils easily as it has absorbed water from the atmosphere, creating vapour voids leading to no brake pedal. After everything cools down, the vapour condenses back into fluid the the pedal returns.

On a recent classic run, my moggie boiled the brake fluid on the way down the Long Mynd in Shropshire - really terrifying, especially for the drivers coming back up the hill against me but a quick stop in the hotel at the bottom and everything was ok again - needless to say I changed the fluid, and it hasn't happened since.

hope you get them sorted

I don't have a shoe adjuster on mine to even each side out. So I have adjusted the handbrake cable adjuster to give 5 clicks so I can rule out any brake binding due to over adjustment if it happens again. Take a look at the photo in the link below.

https://www.flickr.com/photos/534470...posted-public/

Thanks for the tips.

You were very lucky that day.

What gets me is I had the OS/F steel brake pipe replaced for the MOT at the start of the year and asked them to do a full fluid change and they tested it and said it passed there special heat test and talked me out of it. It was jet black when I did the fluid change the other day.

Interestingly a fluid change sorted another problem out that I couldn't get to the bottom of. The car has been in the family for around 6 years. My sons girlfriend had it for at least 2 years before that. There has always been a thump when pressing the foot peddle down first thing in the morning, like it sticks and then its fine for the rest of the day. So its been like that for at least 8 years. It hasn't done it for the past 5 mornings since the new fluid change. How strange is that.

Thanks

Technical Seicento MPI 2002. Total brake failure, help needed

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Technical Seicento MPI 2002. Total brake failure, help needed