the Z31 and quite a few late 80's / early 90's vehicle platforms use a vacuum pump to provide pneumatic operation of the climate control, heater valve, cruise control, and other related accouterments. locking hubs on some SUVs too.

engines with certain lopey/high overlap cams do not generate good vacuum assist either- making brake boosters nearly useless.

It just occurred to me that I had a vacuum pump on the M6 I parted out, I guess I sold it, Duh.

Someone on another forum suggested hooking the pump to the brake pedal with a relay, I might try that.

On 8/29/2016 at 9:51 PM, Captain Obvious said:

Well I guess I know less about diesels than I thought I did... Why can't they use manifold vacuum on a diesel? They do generate manifold vacuum, right?

I guess if it's a turbo (which sometimes may generate positive manifold pressure) there might be a problem, but is there still an issue on a N/A diesel?

Diesels are un-throttled engines. There is no throttle plate on any diesel, so they do not generate vacuum in the intake. They regulate engine speed via fuel delivery only. So all diesel cars that use vacuum controls have some form of a vacuum pump. The dreaded Oldsmobile diesel's of the 70's and 80's had a mechanical vacuum pump where the distributor would normally be mounted on a gasoline engine. (The EGR, dashboard heat/AC controls, and automatic transmissions of that era were vacuum driven.

3 hours ago, grannyknot said:

It just occurred to me that I had a vacuum pump on the M6 I parted out, I guess I sold it, Duh.

Someone on another forum suggested hooking the pump to the brake pedal with a relay, I might try that.

I suspect that would be too slow.

 

7 hours ago, Walter Moore said:

I suspect that would be too slow.

 

What if I apply the brakes for 10-30 sec. after start up and before driving off?  That would pump down the booster and vacuum canister so every time I applied the brakes after that the pump would be 'topping off' the vac canister.

17 hours ago, grannyknot said:

It just occurred to me that I had a vacuum pump on the M6 I parted out, I guess I sold it, Duh.

Someone on another forum suggested hooking the pump to the brake pedal with a relay, I might try that.

Are you talking about using a relay on the pump in lieu of a vacuum receiver?  IMHO that's a terrible idea.  The ideal situation would be a vacuum pump with a pressure switch that will cycle on and off based on the vacuum in the receiver.  The receiver is then available to provide a nearly constant source of vacuum to the brake booster.  

Yup ^^^ what he said. Switched power so it doesn't run when the car is off

Chris,

The volvos, anything after 2004 should have an eleftric vac pump and a vacuum switch to activate the pump when the vacuum is low. The pump will activate with key on until the switch de-activates it. Wel thats how the XC90 2006 model works.

Im sure a volvo would be easy enough to find at a pick & pull or you could buy a new switch.

https://www.fcpeuro.com/products/volvo-brake-booster-vacuum-switch-xc90-31265826

Its a pitty you tossed the bmw unit in the garbage. Mmm you are starting to make a habbit of losing good parts in the garbo.

A lot of european makes use mechanical pumps for vacuum. VW use one that looks like a distributor, and renault have one on the end of the cam shaft. Volvo seems to like the electric version.

 

 

2 hours ago, EuroDat said:

 

Its a pitty you tossed the bmw unit in the garbage. Mmm you are starting to make a habbit of losing good parts in the garbo.

 

 

Chas, I sold it, the bmw vacuum pump is part of the M/C unit.  I don't throw all the good stuff out you know, I just didn't realize that I would need it.

Okay, electric vac pump with vac switch and a canister.

Thank you all.