Brake aux vacuum pump is blowing air..!

[irishcarfan]

Evening all,

I've been fighting with a 1999 Volvo S40 (B4184S2) 1.8 Auto for weeks now and the latest development was a hard brake pedal - not the usual one when it's hard from cold, but it's hard permanently.

The first thing I found was a blown fuse for the vac pump. Great, I thought, but after putting in a new fuse, something sounded noisy (the car was up on ramps, had just changed the radiator). Long story short, after disconnecting the hoses to the aux vacuum pump, the pump is blowing air. Even if I reverse the wires to it, it still blows. At the hose to the servo, it hadn't felt like there was vacuum and, despite the check valves, I could swear I had felt it blowing, which is what made me question it. Btw, when I blow into the hose that the pump is connected to, heading to the servo, it does hold air and the check valves might be okay..

Just wondering has anyone come across this before? I should say that as I had changed the radiator, thermostat, filters etc. and all engine mounts, inc. trans mount, I had thought maybe I had knocked something, however, after a lot of searching and examining, I don't think I have.

I could not find anything odd looking on the lines and hoses - all appeared in good condition and very obviously not touched since 1999. I do have a question: on this S40, do the brakes work only on the aux vacuum pump? Or do they also work on the intake manifold? I haven't checked it yet, but I suspect I should've felt some vacuum if there was something from the intake? Unless this magical vacuum pump was countering it.

I've been reluctant to randomly pull at stuff as I've been finding it difficult to find parts should anything break. I know there is a replacement pump and a kit for it. I can see a check valve p/n 30630516 on Skandix.. out of stock. However, it looks like there is another valve on the servo hose, which I can't find a p/n for.

Interested to hear any thoughts or experience on this from you guys. I've read through every thread here and multiple other sites. I know these pumps fail due to water ingress (the box it sits in is very rusty..), but does this result in them blowing air? And could this have caused other issues?

Cheers!