Vacume pump

**vince-305** · 22-12-2009 09:36

Im wondering if the vac pump (that fits on the alternater) off a diesel would work for the brake servo on a petrol

**100ev8** · 22-12-2009 09:44

i think old peugeot diesel's had a belt driven one that had a fair bit sucki sucki

**30psi** · 22-12-2009 10:24

Yeah it would work, but why use that when you already have a vacuum source

**chris** · 22-12-2009 10:27

he's got idle hands i reckon and just wants to 'fiddle'

unless he's found a big ole supercharger............ ?

**kapri** · 22-12-2009 10:33

I reckon he's just concerned about lack of vacuum from a wild cam ? Most of those pumps require an external oil supply as well Vince.

**30psi** · 22-12-2009 10:36

I had an engine with a lack of vacuum from a wild cam on one of my old cars. It only was an issue when manoeuvring the car at idle say in a carpark or something. A blip of the throttle saw the servo get regenerated.

**kapri** · 22-12-2009 10:47

On autos it can play havoc if you are still running a vacuum modulator on the gearbox though. Even some modern cars run electrical vacuum supplement pumps due to problems with cam timing , Volvo V and S range.

**30psi** · 22-12-2009 10:52

Yeah thats a point, mine was a manual, but the current car is an auto with a vacuum modulator. Be interested to know more about those Volvo's having additional pumps, you'd expect the cam timing not to be an issue, unless it's something to do with ridiculous emissions piping cocking it all up. Have you noticed though how some modern cars have really powerful servo assistance, perhaps they just want the brakes to be as light as possible.

**kapri** · 22-12-2009 11:01

On the V and S series it is to do with the VVT set up . My understanding is that at initial start up and runing the engine produces insufficient vacuum to work the brakes.

Volvo also used them on the 760Turbo series , after some research they are an AC Delco unit used on some Cavaliers in the States also available new frm MP Brakes.

Some info about on them on electric vehicle sites where they need an electric pump to run the servo assist .

I have to agree about a lot of modern stuff being horribly over assisted.

**firebird68** · 22-12-2009 13:53

Some '60s GM muscle cars had the option of non-servo disc brakes. A buddy ran these on a '67 automatic Firebird and said they worked quite well. If lack of vacuum is the problem one of these non power master cylinders might be an easier fix.