Vacuum pump order of parts

[FFMan]

I'm using a vacuum pump off some other vehicle to boost the brakes in lieu of engine vacuum.

I have the pump, then a non-return valve, then a small reservoir and then the servo. The pump doesn't seem to want to stop running, it slows and almost stop but keeps firing intermittently. I've checked for vacuum leaks but wondered if the order of parts was critical i.e. does it matter where the non-return goes, and whether my reservoir is too small (though the pump should still stop).

anybody else had issues with this ? does everyone run a reservoir ?

[arber333]

I'm using a vacuum pump off some other vehicle to boost the brakes in lieu of engine vacuum.

I have the pump, then a non-return valve, then a small reservoir and then the servo. The pump doesn't seem to want to stop running, it slows and almost stop but keeps firing intermittently. I've checked for vacuum leaks but wondered if the order of parts was critical i.e. does it matter where the non-return goes, and whether my reservoir is too small (though the pump should still stop).

anybody else had issues with this ? does everyone run a reservoir ?

Well you need to fit the things in that order:

<pump> ---- <check valve>----<sensing switch>------<servo>

I use Volvo XC90 switch as it has 10mm stubs for hoses. It also has inbuilt check valve (membranes) which effectively eliminates the need for extra valve. My system looks like this:

<pump> ------<sensing switch>------<servo>

Other problem would be you have a leaking servo membrane which would be easy to fix - replace the servo drum.

[FFMan]

ok thanks - do you have a vacuum reservoir ?

I think the servo is ok, it was fine before i pulled the engine from it, though of course it could be hard to tell with the engine providing continous vacuum.

[arber333]

ok thanks - do you have a vacuum reservoir ?

I think the servo is ok, it was fine before i pulled the engine from it, though of course it could be hard to tell with the engine providing continous vacuum.

No it is enough vacuum inside my servo for 3x brake press.