Cheap Vacuum Pump

DISCLAIMER - AS BRAKING IS A CRITICAL SYSTEM BE 100% SURE OF WHAT YOU ARE DOING BEFORE ATTEMPTING ANY WORK ON THE BRAKING SYSTEM.

ALSO BE EXTRA CAREFUL USING SECOND HAND PARTS OF ANY ORIGIN, ESPECIALLY UNKNOWN.

I TAKE NO RESPONSIBILITY FOR ANYONE TRYING THE FOLLOWING.

Liking to trying to do things a bit differently I have obtained an electric servo pump from a late Vauxhall, IIRC a 2013 Astra.

The same pump is used on many makes of vehicles in different configurations.

Initial investigation...

The unit I found had three wires and a rubber hose coming out of it.
I snipped the wires where they went into the main loom.
I followed the hose became a plastic pipe which eventually lead to the brake servo, on route it went through a "unit" which had 2 wires, again snipped where they went in to the loom.

The wires from the vacuum pump were red, brown and a thinner black one with a white tracer.
I tried several permutations to try and get the pump to work but nothing succeeded.
I tried researching on line but could only find info about the basic pump with 2 wires so I gave up and lost it in the shed.

Tidying up a couple of weeks ago I came across it again and decided I had nothing to lose so stripped it down.
The pump looked fine so I turned my attention to the electrics and this is what I found!

Oh! No wonder it didn't work.

Researching Vauxhall wiring it transpired that they use red for power and brown for earth, not the BL/Austin/Rover/MG colour scheme of black for earth, brown for live and red for switched live!
While testing I must have put power through the earth and so on and so forth.
This has burnt the electronics which must have been a solid state relay, now it was just a right state! LOL!

Once I had removed all of this I found 2 x 6.3mm female terminals.
Connecting these correctly to live and return and the pump, well, um, pumped.

I turned my attention to the "unit". This had a black wire and a black/white wire which is the same as the third wire on the pump. This "unit" turned out to be a vacuum controlled switch that opens and closes to control the power to the pump.

More to follow when I have taken more photos.

Finished the wiring today.

I had a professional wiring diagram made up...

Added a fuse, nicked from a scrap wiring loom from a TF. It is the one on the engine loom for the alternator. I replaced the 70amp fuse for a 30 amp one.

I added a fused relay behind the under bonnet fuse box. It has the yellow 20 amp fuse, the other relays are for the heated front screen.

Finally I tidied it all up with a cover fashioned from a telescopic air vent used in house building.





All that is left to do is modify the airline and connect.

I also need to locate a supply for the switch line into the relay. I had planned to use a permanent live so that I have servo assistance at all times but when testing with a finger over the end of the vacuum pipe the pump was pulsing every 10 seconds. If this happens when it is properly hosed up it will have to be a switched live.

Looks great TC - I'll probably follow your lead on this while my car's laid up. I'd have it on the road, but money's tight and it needs sill welding, four new tyres and exhaust repair before it'll pass an MOT again, so it's laid up for now. (also there's nowhere to drive it, coronavirus etc.)

Out of interest - why did you electrify the vacuum on your car? With plans to keep the engine intact, you've got a source of vacuum available w/o the pump.

Thanks.

Why? Because I can.

Hi Talkingcars
What do you want to achieve with the pump? Better brake assist?
Is the normal assist using vacuum from the engine or..?