How to remove break servo?

[Killerko]

Hi, I bough 406 2.0 HDi 110 and it has very hard break pedal and breaking is a bit weak.
I've checked all break pads and disks and they look in pretty new condition.. rear right caliper is a bit seized, and the pad is wearing a bit unevenly, easy fix but that is not why the pedal is hard. I suspect some vacuum problem or break servo.

I did the basic pedal test when you pump the pedal until it's hard (even tho mine is hard right away on first try) and then start the car the pedal start sinking slowly..

I've checked the one way valve and it looks like its working correctly, you can only blow to it from one side, the other won't let you.
I've also checked the rubber seal that the valve goes into and I messed up by trying to put it back in as I pushed it all the way in and it's disappeared in the black hole of the servo... ..luckily I have another 406 which is in the state of engine being opened, so I borrowed the rubber ring from that servo ..but I would like to get that little guy out from there. (If I can remove the servo first..)

Then I've checked the vacuum pump by unplugging the cable and had the car start and checked if there is suction.. which there is, it's not very strong.. not sure if that's normal, but the pump appears to be working. Then I tried to ignore the other lines that go god knows where to the left side behind the engine and only make direct connection from pump to the valve that goes to the servo and started the car, let it run for some time but pedal is still hard and it looks like there is no vacuum being made in the servo (leaking somewhere inside?). Also when I look behind the servo there is a cable tie there and the rubber boot is not properly seated. Looks like somebody was already "fixing" it..

So, I've tried to unscrew the break cylinder and move it away from the servo a bit, but then how do you reach the 4 bolts that holds the servo in place? There is not much space there..
How do you remove the break servo from the car?

There seems to be no video of this online.. the closest I was able to find is this video from a coupe where servo is already out and the guy is working on removing the linkage to the pedal (which I hope I don't need to do): https://www.youtube.com/watch?v=6VmPCn4ovnk

Also this video of somebody removing servo from not a 406: https://www.youtube.com/watch?v=rtbF59-znhI

Any help would be appreciated in how to remove that ufo from the car to inspect it, get my rubber seal out of it and maybe fix/replace if there is something wrong with it.

Some pictures I've took: https://imgur.com/a/aQAV4Vc

[frog]

The Haynes manual says:

Right-hand drive models

Note: Access to the servo unit and crossover
linkage is exceptionally poor (especially on
diesel models) but can be improved by
removing the cylinder head (where possible)
or the engine!

[Killerko]

But, do I need to touch the linkage? I just want to remove the servo itself..
In the video of coupe the guy managed to remove servo without removing the linkage.

[Killerko]

Also I'm having a bit of trouble to identify the correct replacement part that I need.
Anybody knows what part number should I search for reg: KV52ZFX or vin: VF38ERHZF81530938

According to catalogs.ssg.asia (if I selected the correct car) there are 2 variants:
BRAKE APMLIFIER UNION RIGHT HAND DRIVE And TEVES BRAKE SERVO And Since OPR 08636 TEVES
BRAKE APMLIFIER UNION RIGHT HAND DRIVE And Until OPR 08700 BOSCH

Bosch part number is listed as 4535J6
and for Teves there are 2 variants:
01 4535 K9 01 BRAKE AMPLIFIER,
DIAM 255 WITHOUT ELECTRONIC STABILITY PROGRAM And Since OPR 08701
01 4535 P3 01 BRAKE AMPLIFIER,
DIAM 255 ELECTRONIC STABILITY PROGRAM

But the sticker on mine says it's Ate and numbers are:
96405-973-80
5.5
03.7864-2301.4
as can be seen here: https://i.imgur.com/eaM4Dzk.jpeg

[steve_earwig]

Teves and ATE seem to be the same thing:

ATE, originally Alfred Teves Automobiltechnisches Material und Zubehörteile, a manufacturer of automotive components, now part of Continental AG

I can't stick your vin in service box (spit) to pull up your build code any more but, judging by my small vin collection the car's well after the semi-mux/full-mux split in 2001 at rpo 9001 so yours is definitely ATE/Teves. The only question is if the car has ESP or not. I think if you have it then you'll have a button to turn it off but it was only an executive thing as far as I know, so if yours isn't an exec then the car almost certainly doesn't have it.

The numbers on the servo may or may not mean anything (and don't bother looking at ebay or whatever as sellers are likely to use any number they see on it, no matter how stupid) but aren't the ones PSA uses/used, the trick would be finding which one actually means anything and then finding a way to convert it, which a lot of the time appears to be a secret

[PeterN]

I had the servo fail on one of mine, the diaphragm developed a leak, I read about the replacement hassle and decided to get rid of it, it had done over 200k so didn't seem worth it. The brakes still worked but you had to leave yourself plenty of room.

Before you condemn the servo check all the pipes for leaks, the loss of vacuum on mine was affecting the turbo output. I ran 406's for about ten years and that was the only serious fault I had, I think they were the best car that Peugeot made.

I had thought about fitting a stand alone servo but couldn't find enough space.

Peter

[Killerko]

Thanks Steve.. looks like I will need to search for 4535K9 then as I don't think I have the ESP.. no button anywhere that would look suspicious.

Also finding the correct servo looks like will be a challenge.. I was also thinking maybe worth replacing the vacuum pump.. it's only £20 used one from ebay.. or even use a dedicated external vacuum pump connected directly to the servo and see if that could make some vacuum to hold it.. I've tried already to isolate the other pipes and only leave the pump being connected to the servo but that did not seems to do much. No vacuum was created inside. I really think something is wrong with the servo itself.

And also since I did all the checks with it, now the pedal is rock solid and do not sink anymore at all.. before, when I relieved the pressure a bit the pedal started to sink and you eventually got a proper breaking power... now, it feels a bit different as it is rock solid all the time and I have to press really hard to stop the car. Wonder what could have changed that. Maybe that rubber seal that I dropped in by accident?
Also the car only done some 120k miles, so it would be a waste to scrap it...

[Killerko]

Good news everyone!

I managed to source the EXACT servo I need.
After couple of days googling everywhere.. I came to the conclusion that 4535K9 is simply not being sold/made anymore.. but funny enough 4535K8 which is the exact same part only for left hand drive vehicles with longer rod that come out on the back is still available.

So eventually I found one on FB marketplace.. somebody was breaking a 406 there so I sent him a message and lucky me, it had the servo I needed.
Now just hope it is in working condition, but the guy said it's working... so we will see.
I also took the master cylinder with it just in case... and now I'm thinking I should probably grab the vacuum pump too when I was there, but that one is available on ebay.
The best part? It cost me £25 for servo and £10 for ty cylinder and £5 for some other random bits of plastic grilles, badges, antenna and oil cap.

Will try to replace it this week to see if it helps my break pedal issue.

[GingerMagic]

That's a good result....

Good luck with the swap.

[Killerko]

So I'm a bit stuck.. I've removed all 4 botls holding the servo, but the connection to the linkage is held with a retention pin and there is really bad access. I can reach it from bellow, but was not able to remove the clip yet..

[Killerko]

So, I have managed to complete the swap, bled the breaks with new DOT-4 fluid and the breaks are working like they should . Further to that.. the repair also solved the limp mode the car was in as I think the lack of vacuum affected the turbo and the car accelerated like snail before and now it feels lot more responsive to gas pedal. So very happy overall. The pedal does feel like its going down a little bit too much tho, (maybe it's just me after driving with a brick of a pedal for 2 weeks) not sure if this can be adjusted somewhere, but the breaking power is superb now.

It was a pain of a repair tho, the space behind the servo was very limited and I lost the retaining clip that was locking the pin connection with the servo so I just put the pin in without securing it heh for now.. until the replacement will arrive.
I posted more pictures here: https://imgur.com/gallery/sM7SCiQ

[Doggy]

Well done.

I chickened out with my last 406 and reluctantly scrapped it rather than take on this job.

If you could just get in your time machine and post this about 4 years ago.....

[frog]

Cool! Well done indeed! From the photo's it looks like yours is left-hand drive? Or isn't it?

[frog]

Ah no, it is a right-hand drive (is it?). The servo is on the left side, which is the same place as on the left-hand drive version.

[Killerko]

Hey frog, It's right hand drive (UK) as you can see in pictures that the rod at the end of the servo do not connect straight but goes 90 degrees to the linkage which goes to the other side to the break pedal.