BMW 1series diesel - Brake servo problems

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Mon 18 Sep 2017 23:12
BMW 1series diesel - Brake servo problems - David Welsh

Hi I've a question regarding brake servo on my car. I seem to be losing assistance from servo if I use the brakes quickly in succession. I've pulled off the vacuum pipe going into the servo and when suck through it I can't get a vacuum just keep drawing air. I'm sure that means the diaphragm has gone but just wondering if I'm missing something. Any advice appreciated ??

Reply | Report as offensive | Link
Tue 19 Sep 2017 08:38
BMW 1series diesel - Brake servo problems - hardway

Petrol or diesel?

It really makes a big difference.

Reply | Report as offensive | Link
Tue 19 Sep 2017 10:09
BMW 1series diesel - Brake servo problems - Railroad.

The OP says it's a diesel. Unlike petrol engines diesels have no throttle valve and therefore no inlet manifold vacuum, and so an engine driven vacuum pump is required for the brake servo. Pull the pipe out of the servo, start the engine and put your finger over the end of the pipe. If you feel good suction you know the vacuum pump is working, and if so then the servo diaphragm is faulty. If there is little or no suction then you either have a split pipe, a worn vacuum pump or a broken vacuum pump drive.

Reply | Report as offensive | Link
Tue 19 Sep 2017 11:03
BMW 1series diesel - Brake servo problems - David Welsh

Hi, I've tested the integrity of the vacuum system up to the servo and its leak free. The vacuum drops when I reconnect the servo. I gues my question really is - is a servo fully airtight or is it designed to have a certain amount of leak past. If it's meant to be fully airtight then my servo is definitely kaput.

Reply | Report as offensive | Link
Tue 19 Sep 2017 11:24
BMW 1series diesel - Brake servo problems - Peter.N.

No it should be pretty well airtight, its rare for one to leak but it sounds as though yours is.

Reply | Report as offensive | Link
Tue 19 Sep 2017 12:28
BMW 1series diesel - Brake servo problems - David Welsh

Hi thanks, I thought so but wasn't 100% sure. I've ordered one from ebay for £20 so not that much of a risk just the pitting which is a bit of a pain but the fluid needed changing on my car anyways.

Reply | Report as offensive | Link
Fri 22 Sep 2017 12:57
BMW 1series diesel - Brake servo problems - David Welsh

Solved! - When I took the old servo out the bottom side had totally rotted out, I'm guessing there was a small internal leak of fluid. £25 servo fitted from ebay and brakes back to being brand new AND the EGR flow engine light has stayed out for over 100 miles now so double win!

Reply | Report as offensive | Link
Sat 23 Sep 2017 14:09
BMW 1series diesel - Brake servo problems - David Welsh

500px.com/photo/229215363/img-20170921-182350-jpg-...h

Reply | Report as offensive | Link
Sat 23 Sep 2017 15:12
BMW 1series diesel - Brake servo problems - madf

500px.com/photo/229215363/img-20170921-182350-jpg-...h

German quality engineering at its best.

Reply | Report as offensive | Link