Peugeot Forums banner

1 - 20 of 33 Posts

·
Registered
Joined
·
52 Posts
Discussion Starter #1
Hey guys, I am in need of some advice further to an earlier thread about an intermittent problem with the brakes on our V6 petrol coupe.

http://www.peugeotforums.com/forums/407-41/brake-failure-eek-30535/

Peugeot have handed the car back to us having been unable to find or fix the fault, despite us paying around £1200 so far for various work.

One of their technicians was using our car daily in the hope that the fault would occur while driving, however this didn't happen as it is very unpredictable, and because their diagnostics don't show any faults they have given up trying to find it.

The last time any work was done we were charged £380 for a new brake servo, but the fault recurred 3 days later. When I said to them I expect to be reimbursed for the new servo, I was told that they had actually found a fault with it, despite it not having a fault on the previous 4 occasions they looked. It's clear to me that the servo was a guess that we have been made to pay for, despite it clearly not being the cause of the problem.

It seems there is no mechanical investigation going into this fault as they are saying they can't do anything unless they have a fault work with, this can't be right?

What else can we do? We now have a car which we know to have a dangerous intermittent fault, and Peugeot are saying they can't help. We have paid them so much money and yet are back at square one. Is it time to get legal with them?
 

·
Registered
Joined
·
14,601 Posts
Unfortunately this is how most big garages work if its a problem they cant figure out they throw parts at it till its fixed
I bought a Renault espace years ago was non runner it was in Renault dealers in stirling they said it needed new ecu etc etc at £1200 guy decided no sold it to me it had stripped its timing belt belt was still on but timing was out !!

12 new rockers and a belt and all was good again :)

If the guy had authorised the ECU replacement the car would still not have run but they would have charged him anyway !!
 

·
Registered
Joined
·
1,019 Posts
Question for dealer:
Are there any recalls that apply to your car.
If so then list them all, and provide evidence that all remedial work has been carried out.

It does sound like a vacuum problem :rolleyes:
How could we test this?
 

·
Registered
Joined
·
1,073 Posts
Is the one way valve working as it should on the vacum circuit?

On early models it is built into the connector on the servo itself, and on later ones I think it's a separate part.

If this somehow sticks open for a while and you try to brake instantly after having quite a lot of throttle I suppose the brakes might not work very well at all. (If it takes the vacum from the intake plenum).

But that said, if it's got a vacum pump, and not getting vacum from the plenum it could as well be something intermittent with vacum pump.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #5
Thanks for the replies.

I looked into recalls and there have been a couple with similar-sounding symptoms, but the dealer has told me these applied to diesel vacuum pumps only. Correct me if i'm wrong but I'm assuming all petrol models will take vacuum from the plenum?

It has happened a few times while manoeuvring slowly but also when driving at motorway speeds, so it seems to be random and not occurring under the same conditions each time. It usually corrects itself after switching the ignition off and on again but not always, it can also start working again while still driving. It isn't just reduced braking assistance either, it's zero, as if the engine was turned off.

I must have had the same conversation with Peugeot several times about how there are only so many components in the braking system to check, but they seem quite open in admitting that unless their diagnostics throw up a fault they don't even look under the bonnet!
 

·
Registered
Joined
·
1,073 Posts
Surely changing the one way valve at least can't be very expensive, neither expensive.

At least taking the existing off and see whether it might be a problem with it just by visual inspection.

It really is a quite simple mechanical system which is vacum operated, and as long there's vacum in the booster it should work.

I had my booster fail though, as I bought a new one because I thought the one I had was at fault. I did not notice that the 1 way valve was not integrated in the new one, and as I have a vacum pump it really didn't show up that there was no one way valve.

However when I applied the brakes the air pressure in the booster increased, resulting in that the booster sucked in oil from the vacum pump! Seals inside the booster started to swell, and after a few days my pedal started acting strange. Once I applied brakes it seemed to do what it should, but after 1 sec or so, the pedal was pushed out making the brakes incredible hard.

Very strange feeling. Due to fluid (oil) inside booster which caused something wrong with internal valves or something like that...

Put old booster with one way valve back, and worked perfect since..

Not really sure what to advice you though.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #7
Well the braking problem returned today, and this time as I was only a mile from the Peugeot dealer I went straight there in the hope it wouldn't fix itself before I got there. Typically the brakes started working as I pulled into the forecourt.

I went in anyway and for the first time in this whole mess I had a face to face chat with one of the technicians. Apparently the one-way valve is integrated into the servo unit so that can also be ruled out. He told me he had never experienced this problem on a Peugeot, other than the diesel models which were subject to a recall, and he also told me they have been in touch with other Peugeot dealers and no-one else has ever come across this.

He said the only way to resolve this is for him to use our car daily with the laptop plugged in, and if/when the fault occurs try to replicate it and go from there. I'm not too hopeful to be honest as the fault seems completely random.

I'm no mechanic, but it seems to me that somehow either the braking circuit has a vacuum leak somewhere or there is occasionally no/insufficient vacuum present at the inlet manifold. The intermittent nature of the problem is the confusing and frustrating thing as it is obviously making it very difficult to diagnose.
 

·
Registered
Joined
·
14,601 Posts
Some cars have an electric vacuum pump to keep the vacuum up at wide throttle openings etc I would ask if yours has 1 just incase its a simple case of power cutting to it reducing vac sometimes as you say fault lights come on too.

I know the 406 v6 did not have a vac pump but 407 may if not fitting 1 might be worth a try for testing purposes.
 

·
Registered
Joined
·
1,073 Posts
Well the one way valve is not that integrated. It can be pulled off the brake booster. It's integrated in the plug where the vacum hose attaches to the booster.

Surely it can't be too hard to diagnose. Either it is a vacum leak or it is the booster.

It can't be anything else as far as I understand, as it's more or less completely mechanical.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #10
Some cars have an electric vacuum pump to keep the vacuum up at wide throttle openings etc I would ask if yours has 1 just incase its a simple case of power cutting to it reducing vac sometimes as you say fault lights come on too.

I know the 406 v6 did not have a vac pump but 407 may if not fitting 1 might be worth a try for testing purposes.
I asked this to be sure and was told my car does not have a vac pump.

Well the one way valve is not that integrated. It can be pulled off the brake booster. It's integrated in the plug where the vacum hose attaches to the booster.

Surely it can't be too hard to diagnose. Either it is a vacuum leak or it is the booster.

It can't be anything else as far as I understand, as it's more or less completely mechanical.
He said the valve is part of the servo so they are replaced together, essentially ruling both components out as the cause of the problem.

I agree, it shouldn't be difficult but the random nature of it makes it so. If it was the hydraulic side the pedal would go to the floor, if it stiffens up it's the vacuum side which basically is the booster, valve, hose & inlet. Assuming the booster and valve are known to be good, either I have an intermittent leak in the hose which wouldn't make much sense, or for whatever reason there is insufficient vacuum at the inlet. Next time it happens if I have the presence of mind I'll pop it into manual shift and see if engine braking seems normal in a low gear.
 

·
Registered
Joined
·
1,019 Posts
It has a vacuum reservoir (3).
It's not clear to me what's going on here.
6 is labelled: solenoid air vent pipe.

The presence of a control solenoid is interesting. When there's a faulty control solenoid on the diesels it's the consequences of the faulty solenoid that cause an error (exhaust gas, boost,...) but there's never a code related to the solenoid itself -- presumably because they're behaving electrically.

 

Attachments

·
Registered
Joined
·
1,073 Posts
Yes it really seem to be a solenoid connected to the rear silencer somehow? What on earth is that actually doing?

I've been looking in servicebox too now, and it surely seem to have a vacum pump, and some extra vacum hoses showing up for some models, probably going back to the vacum reservoir and solenoid.

You can also see the one way valve, number (5) in this pic, can be changed separately, but I'm starting to think your fault has to do with the vecum reservoir and solenoid.



The car even should have a vacum pump! Very strange the garage didn't notice this?

 

·
Registered
Joined
·
52 Posts
Discussion Starter #14
Many thanks gents, I shall investigate further. It's not clear to my untrained eye where that vac pump is located - where should I be looking for it?

I'm at a loss to explain why the Peugeot tech told me it had no vac pump.
 

·
Registered
Joined
·
1,073 Posts
It's located at the end of the cylinderhead, normally driven by one exhaust camshaft.
Opposite side to the cambelt.

So called techs are often not as clever as one should expect from their titles :)

I'm never getting any good answers to technical questions at the main dealer over here either. Other than "you need to bring it for a diagnosis" of course.
 

·
Registered
Joined
·
14,601 Posts
If you are willing/brave enough :) to travel down to Falkirk I will have a look and see if it has a vacuum pump for you and show you all the pipework you can then go to the dealer with the knowledge of what is actually there and what is not !!

If it does indeed have a vac pump then the fault most definitely lies in this area somewhere either the pump is not always working or there is a leak in the pipework or the valve mentioned is not working correctly its basically the same as HDIs no vac = no boost but in your case =no brake boost !!
 

·
Registered
Joined
·
52 Posts
Discussion Starter #19
Thanks again for all the help.

So am I to understand that some petrol V6 motors have a vac pump and some do not? Unfortunately I'm away with work so can't get the VIN at the moment.

Peugeot are taking the car off us again later this week to use daily and try to replicate the fault. I have told them to keep it for as long as it takes as it's no use to us as it is, but I will definitely be going over for another conversation with them after what I have learned here.
 

·
Registered
Joined
·
52 Posts
Discussion Starter #20
Update.

The fault occurred while the Peugeot tech was driving with laptop plugged in etc, but no fault was detected despite the braking assistance not working for over 2 miles.

It has been logged with Peugeot HQ now and they are not allowed to give us the car back as it's a safety issue, so who knows what will happen from here. They have admitted they have no idea what could be causing this and this fault has never been reported before on a petrol engine across the dealer network.

Just out of curiosity regarding the vacuum pump discussion above, our VIN is VF36JXFVJ21426556 if someone fancies clearing it up. Thanks.
 
1 - 20 of 33 Posts
Top