wrote:

>Hi,
>
>I have a 82 diesel vanagon and I've been having problem with the power
>break system. When the engine is cold, I get absolutely no assistance
>from the power break, so it's quite hard to stop the vehicule. After
>driving it for a while, I start getting some assistance and the pedal
>gets softer on the driver. However, if I depress the brakes several
>times, the brake pedal gets hard again, as if the vacuum pump could not
>supply enough vacuum (diesel engine here). Brake booster looks fine
>(air thigh) as the brake pedal works properly after the van has been
>parked for a few days (assuming the brake were ok when parked of
>course).
>
>Any idea on what could cause this?
>
The diaphragm in the vacuum booster pump is probably shot.

The get a hole worn into them after a time.

It's about a 15 minute job and the diaphragm kits I have bought were
like $15.