# 12V Power Brake Vacuum Pump



## mora (Nov 11, 2009)

Some newer Volvos have 12V electric vacuum pump. I found mine from car wrecker. I use it in mk2 Golf too. Works fine. I believe pump came from S60 model. It doesn't have vacuum switch built-in but it is simple to operate at least. Only two wires coming out of the pump. Apply voltage directly to the wires and pump runs.

http://www.ebay.com/sch/i.html?_fro...313&_nkw=up28+volvo&_sacat=See-All-Categories

eBay listing tells that the same pump fits to V70, V40, S40 and XC70 too.


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## Ace_bridger (Nov 22, 2011)

Thanks Mora. I'll try and track one down in the UK. How do you switch yours? I've not installed one before...do you switch it off the brake pedal? If so, will it provide vacuum in time to assist the brakes? Or does it runs all the time whilst driving?

Any help gratefully received.

Cheers,

Adam


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## mora (Nov 11, 2009)

I bought two separate vacuum switches and built simple RS flip-flop logic which enables/disables the pump. Vacuum switches were few euros each and are adjustable. Whenever vacuum is low pump runs and when there is enough vacuum logic shuts down the pump. Should logic fail pump runs continously when I turn ignition switch. Should be failsafe. I have simple vacuum gauge attached to the system and I can adjust low and high limits using screwdriver.

Use vacuum reservoir so you don't have to cycle pump after every press of brake pedal. I used 2kg fire extinguisher as reservoir and I have lots of pedal presses before vacuum runs low. Even if vacuum is low brake pedal isn't too hard to press. Even vehicle inspectors were happy with this.


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## Ace_bridger (Nov 22, 2011)

Good stuff, many thanks.

Lots to think about and I'll go and design and get parts around me.

Many thanks,

Adam


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## dtbaker (Jan 5, 2008)

D-square makes a mechanical vac switch... available here in the states.  you can look at the Kit from kta-ev.com and perhaps find similar parts. simple PCV pipe works for a reservoir and a gauge helps with the initial setting, but probably not ever required after that....

I have a couple pix on my site showing the 'standard setup'.

This 'kit' ends up being kind of pricey. There are some automotive units that might end up being less expensive, but I have not tried one.


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## favguy (May 2, 2008)

This thread got me thinking, as I don't like re-inventing wheels where it can be avoided! 

How do production ICE cars such as VW's that use this type of vacuum pump deal with vacuum control, do they run continuously or via a vacuum pressure switch? If they do use a pressure switch, would it not be simpler for us to source the same one as fitted by the oem?

*update*

I've just read up on the VW oem system, uses a voltage signal from a pressure sensor to tell the ECU the pressure, ECU then switches the pump, so oem sensor is probably no use!


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## dtbaker (Jan 5, 2008)

on this vacuum pump issue, and heater switches, I've been looking at alternatives.... and keep coming back to the de facto standards that KTA-ev.com has sold for years. Over time I think they zeroed in on pretty good dependable solutions. I keep LOOKING, but have growing respect for what they settled on for kits.

Gast/Thomas vac pumps, PVC reservoir, squareD switch.... 
ceramic core, hefty contactor (not solid state) for heater....


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## Ace_bridger (Nov 22, 2011)

I'm coming to the conclusion that a quality system is definately prefered!! It is brakes afterall!! 

I did find out that Landrover do a 12V vacuum pump for their vehicle. I missed out on a brand new one on FleeBay yesterday (I was in bed!).

I think a decent pump, PVC tubing with correct fittings, reservoir, check valve and pressure switch would offer a good solution. Just need some sort of time delay/hysteresis to discourage rapid switching.

A kit would do this with ease I'm sure.


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## favguy (May 2, 2008)

Hi Ace,

I'm glad you were in bed, as I think it's the one I bought, lol!!

It's worth keeping an eye out for the Landrover units, they seem to be lower cost than the VW units and appear to be virtually the same in construction and quality, certainly should be up to the task.

Mora's switching solution sounds good. Another option that should work and won't need additional circuit building would be something like the Wasco V110-31W3, (link below) you can use this to directly run a relay to switch the pump and it's got good hysteresis control to avoid the pump running too many short bursts. They don't seem readily available in the UK, but come up often on ebay US for around $20 - $30.

http://switches.wascoinc.com/item/s...g-range-v110-series-1043/v110-31w3-id-88029-#

Regards,

Paul


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## Ace_bridger (Nov 22, 2011)

Haha, well I hope it's a goodun and you'll have to let me know how you get on with it.

I'm not in need of it yet anyway so I'll keep my eyes peeled. A controller will be my fisrt purchase I think.

Thanks for the switch suggestion, again I'll keep um peeled!


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## cts_casemod (Aug 23, 2012)

favguy said:


> This thread got me thinking, as I don't like re-inventing wheels where it can be avoided!
> 
> How do production ICE cars such as VW's that use this type of vacuum pump deal with vacuum control, do they run continuously or via a vacuum pressure switch? If they do use a pressure switch, would it not be simpler for us to source the same one as fitted by the oem?
> 
> ...


Good way of thinking favguy.

You can get mechanical vacuum sensors from most cars. 

Only a few have a sensor like you describe, most have a mechanical on-off type, BUT you need a relay to operate the pump itself. 

Contrary to what you say I would use an electronic one, you can use a simple comparator circuit to set up your on/off pressures quite easily as the ECU does, but keep a mechanical one conected to the brake fluid level so in case you have a failure the light will come on dash as sometime they read the wrong value as they age, similar to the coolant sensors.
If you want to be really cool you can even vary the pump speed to have a more silent operation with such a sensor. Again, same as the coolant fans

And yes, when the sensor goes bad the pump defaults into always on mode... well... at leats untill it burns up.

Problem with these OEM sensors is they cost a fortune and are not adjustable. You can get them from the scrap yard but for what they ask (14-30£) you might as well get a new one for EV use for the same price, unless you can source a second hand one for free. After all, if it breaks tomorrow you wont be in a loss.

Another option are the switches for the older auto transmission/gearbox. They use vacuum to switch gears and a few of them are adjustable.


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## dtbaker (Jan 5, 2008)

I am using a little adjustable vacuum sensor with SSR in my Miata... way smaller and lighter than the typical square-d mechanical switch. They are a little more expensive, but do show up on eBay for $20 or so. The Gast or Thomas pumps are pretty expensive, but occasionally show up here in the classifieds.

mmmm, as a matter of fact, I think I have a 'complete' vacuum kit on the shelf, used, but working that I could sell for good discount. email me if u r interested...


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## cts_casemod (Aug 23, 2012)

dtbaker said:


> D-*square makes a mechanical vac switch... available here in the states.*  you can look at the Kit from kta-ev.com and perhaps find similar parts. simple PCV pipe works for a reservoir and a gauge helps with the initial setting, but probably not ever required after that....
> 
> I have a couple pix on my site showing the 'standard setup'.
> 
> This 'kit' ends up being kind of pricey. There are some automotive units that might end up being less expensive, but I have not tried one.


Is there anything that is not available in the states dtbaker? 

Poor of us here in Europe paying fuel at twice the price and without anything... 

But lets face it the way people think in here is not the way to go. I am impressed the Europe hasn't colapesed yet. 

I feel inspired by many of the conversions and support from people in the USA/Australia. The detail given, etc...


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## bluefxstc (Dec 29, 2007)

I used a pump and reservoir from a 1986 300ZX turbo. Most turbo charged cars and trucks will have some sort of vacuum pump since the turbo eliminates most vacuum, at least when it is producing boost. I think a lot of the truck vacuum pumps are mechanical but believe the small car market is mainly electric pumps. The reservoir in the 300zx had a built in vacuum switch to turn the pump off. I would think the reservoir from most turbo cars with electric vacuum pumps would have some form of switch to turn the pump off.


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