Unknown Braking Problem

[cwhaley]

I have a braking issue with my Peugeot 406 (2.0 HDi 90, 2001). The car does 25 miles a day in the week (just up the M1 and back for work). It is used at the weekends and for other trips moving stuff about.

I’ve found that if more than a few journeys are made throughout the day, the car will spontaneously apply the brakes on its own. It isn’t with a great deal of force and it might only happen once or twice, but it’s enough to hold the car back and the brake lights will come on. Not ideal... I’ve also noticed the speedo needle will occasionally drop to zero for a few seconds, although this happens randomly and doesn’t seem connected to the brakes (but thought I’d mention it). I pumped the pedal for a good 10-15 seconds with the car off -- the pedal didn't get any harder and when the ignition was switched on, the pedal didn't drop. Is this indicative of anything?

I’m off to Cornwall in September with the wife and baby, and I’m concerned about it. Could it be the servo? I’ve checked the only rubber pipe I can see going into it and it doesn’t appear damaged. The pads have plenty of life in them and everything checked out at the last MOT.

Any thoughts on what this could be? Money’s a bit tight at the moment so I’m reluctant to hand the car over to a garage where the costs are unknown.

On the plus side gave her the 3k oil change yesterday and the engine’s still purring lovely at ~170k.

[PeterN]

I was going to say that you have a front brake intermittently binding but if the brake light is coming one that would suggest pressure in the system. A failing master cylinder could cause, if the rubbers have swollen they could be blocking the pressure release hole.

Any particular conditions that cause this or is it random? I would suggest that when the brakes have been binding you check the temperature of both front brakes and see if they are the same.

Speedo problem could be the speed sensor on the gearbox, just above where the o/s side drive shaft fits

Peter

[cwhaley]

I was going to say that you have a front brake intermittently binding but if the brake light is coming one that would suggest pressure in the system. A failing master cylinder could cause, if the rubbers have swollen they could be blocking the pressure release hole.

Any particular conditions that cause this or is it random? I would suggest that when the brakes have been binding you check the temperature of both front brakes and see if they are the same.

Speedo problem could be the speed sensor on the gearbox, just above where the o/s side drive shaft fits

Peter

Makes sense re the master cylinder. I didn't know where the pressure relief hole was so gives me something else to check (hoping it's easily-accessible!)

I've noticed it to be random. Sometimes it happens just once within 5 minutes of setting off (always at the same point, at a set of traffic lights at the bottom of a hill). If it's not then it will just start to happen after driving for more than an hour or so. I'll check the temperatures when I get home but I think last time I did this nothing seemed untoward.

I'm going to ignore the speedo problem for now as it is rare and doesn't appear connected. Thanks for the tip on what controls it however.

[PeterN]

The pressure release hole is in the master cylinder, when thr piston goes right back it uncovers a small hole which allows the fluid to run back into the reservoir. Its usually oil contamination that causes the rubbers to swell.

Peter

[cwhaley]

The pressure release hole is in the master cylinder, when thr piston goes right back it uncovers a small hole which allows the fluid to run back into the reservoir. Its usually oil contamination that causes the rubbers to swell.

Peter

Thanks Peter. I'll try and locate it (presume it's near the servo) and see if I can find the hole so to speak. I've very familiar with the old Lockheed cylinders and there was a small relief hole on the lid of the cylinder, but I imagine this is less obvious.

So far this week I haven't noticed the problem manifesting itself, but I know it will do it after a few stops on the way to Cornwall. It did it on the way to Blackpool a few weeks ago after a stop at a station.

Weighing up a timing belt / pump change before the end of the year as it was last done 50k ago, but not sure it's worth the expense if I can't fix this.

[cwhaley]

Well I made it to Cornwall and back. Currently covered 700 miles and have about an eighth of a tank left -- not bad for an 'old diesel'!

The braking problem did occur on a number of occasions (perhaps 3 or 4 times), but I found lifting the pedal up with my foot stopped it happening again. I also found that after pressing the brake pedal, the lights stay on for a second or two after. Not sure what it's symptomatic of but for now I'll see if it gets any worse.

[PeterN]

I wonder if the pedal return spring has come off or broken? or if something is holding the pedal down?

Marvellous cars those I have had several, best cars Peugeot made in my opinion.

Peter

[cwhaley]

I wonder if the pedal return spring has come off or broken? or if something is holding the pedal down?

Marvellous cars those I have had several, best cars Peugeot made in my opinion.

Peter

Possibly! It all looks very hidden and difficult to get to. Think I need to stick my head up there and see what's happening while I press the pedal (or implement the use of a bungee cord around the steering column......)

Yes it is brilliant. I've already decided after a few years of ownership that when this one becomes uneconomical to sustain, I'll buy another one! My wife has the new car in her job (district nurse), I would rather have 406 with no plastic bulk, DPF filters or hidden engine parts!

[cwhaley]

Well.. got the Pug back from another failed MOT. One rear disk was warped, one pad was worn down to 1mm, one front caliper was seized and I think one of the handbrake cables were perished away. I think the sheathing on them breaks down and the inner cable corrodes.

All jobs that can be done from home, but I just never have the time other than for the yearly oil and filter changes.

Not had chance to drive the car, but hopefully this was the cause of the issue (the stuck caliper). If not, then I'll check the status of the spring on the brake pedal.