Member Since: 02 Oct 2017
Location: lincoln
Posts: 81
brake servo or something else?
This is a new one for me, even as a qualified mechanic that worked in the trade for ~5yrs -I can't remember ever changing a servo
Today I got the dreaded mot fail which all stemmed from poor brake performance; I fitted new calipers and brackets last year and it's had new discs and ceramic pads all 'round over the last couple of months but I had noticed I needed to press the pedal quite hard when braking recently (just assumed that's the difference with ceramic pads) so I wasn't particularly surprised.
The tester said it's likely to be the servo but, when I took the vacuum pipe off of it after 30mins of no running, it drew in a lot of air - so the vac pump is probably ok and the diaphragm not split, no leaky pipes - to my mind at least.
Any suggestions?
I can bodge some way of measuring the vacuum from the pump, anyone know a rough figure to expect on the vacuum guage?
I don't mind changing the servo if needs-be just to rule it out but I thought I'd ask here first. I saw about the recall when I searched but it looks to have been done (by the pipe arrangement) and no signs of oil in the pipes
12th Jan 2021 5:13 pm
Admirable
Member Since: 19 Jul 2015
Location: Fife
Posts: 1016
There was a servo recall, do your pipes look like this, if so it's not had the recall done.
Click image to enlarge
12th Jan 2021 5:27 pm
hotshot
Member Since: 02 Oct 2017
Location: lincoln
Posts: 81
No, it splits outside the box and has a little one way valve in line. Pretty sure it's been done after reading other posts about it
12th Jan 2021 5:42 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10370
these do have a problem with oil getting in the servo.
There was a recall
If you remove the vac pipe from servo, and dip a cable tie into the bottom, see if it comes out with oil on it.
12th Jan 2021 5:45 pm
hotshot
Member Since: 02 Oct 2017
Location: lincoln
Posts: 81
Here's mine;
Click image to enlarge
Vac pump seems to work fine too;
12th Jan 2021 6:54 pm
eightfoot
Member Since: 12 Apr 2015
Location: sunny essex
Posts: 762
Re: brake servo or something else?
hotshot wrote:
This is a new one for me, even as a qualified mechanic that worked in the trade for ~5yrs -I can't remember ever changing a servo
Today I got the dreaded mot fail which all stemmed from poor brake performance; I fitted new calipers and brackets last year and it's had new discs and ceramic pads all 'round over the last couple of months but I had noticed I needed to press the pedal quite hard when braking recently (just assumed that's the difference with ceramic pads) so I wasn't particularly surprised.
The tester said it's likely to be the servo but, when I took the vacuum pipe off of it after 30mins of no running, it drew in a lot of air - so the vac pump is probably ok and the diaphragm not split, no leaky pipes - to my mind at least.
Any suggestions?
I can bodge some way of measuring the vacuum from the pump, anyone know a rough figure to expect on the vacuum guage?
I don't mind changing the servo if needs-be just to rule it out but I thought I'd ask here first. I saw about the recall when I searched but it looks to have been done (by the pipe arrangement) and no signs of oil in the pipes
did you see how the tester checked the brakes for the mot,did he drive it or put it in the brake rollers ?please excuse any grammer/punctuation mistakes,i'm thick,thankyou
current vehicles 2005 d3 2013 d4
12th Jan 2021 6:59 pm
hotshot
Member Since: 02 Oct 2017
Location: lincoln
Posts: 81
I saw him drive it, I don't know if he'd tried the rollers first or not though
I can't see it being anything else now, the vacuum pump gets most of the way to 30 inches so that's good and most of the rest of the system is under a year old - which leaves the master cylinder and servo... just wanted to check before I threw £100 at it and made no difference!
Soo, I've ordered a trw servo and the flexi pipe I also need to change (corroded ferrule) just gotta hope for reasonable weather at the weekend now and I'll report back once it's done
12th Jan 2021 7:16 pm
aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2459
As Pete K says check your old servo for oil, if you fit a new servo you could be in the same situation in a few weeks if your vacuum pump is leaking internally
12th Jan 2021 7:35 pm
hotshot
Member Since: 02 Oct 2017
Location: lincoln
Posts: 81
Good point, will do
12th Jan 2021 8:03 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
I avoid working on cars like the plague, but I have personally changed three servos on my own cars over the years, so any full time car mechanic would have done loads.
D3 brakes are not exactly the best even when in fine fettle, in fact I would say any mediocre every day car has better feeling brakes.
12th Jan 2021 8:49 pm
hotshot
Member Since: 02 Oct 2017
Location: lincoln
Posts: 81
Nope, I've worked on everything from milk floats to artic's to brand new cars in a dealership plus around 10 years on my own cars since then and I'm sure I've never changed one before! Master cylinders, abs units etc but for some reason never a servo
12th Jan 2021 9:27 pm
highlands
Member Since: 11 Jan 2010
Location: NW Highlands
Posts: 5096
30 years of fettling cars and I'd never done a brake servo...until I owned a Disco3! Black 05 TDV6 HSE Auto
Grey 05 TDV6 HSE Auto (Gone)
54 TDV6 SE Man (killed by me )
13th Jan 2021 1:57 am
hotshot
Member Since: 02 Oct 2017
Location: lincoln
Posts: 81
Servo sorted it, now the best they've ever been. Thanks for the replies
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