Afternoon all. Having a play with my Bialaddin 315, and the opposite effect of the 'pump sliding out' syndrome is happening! It's building pressure, and running normally, with no leaks, but the pump is being sucked in. I wondered if this is a regular problem, and does it matter if its working OK? I topped it up with Paraffin before this happened, and don't really want to drain it to replace the NRV pip (if that's the problem). Cheers Guys.....
Call Ghostbusters... On second thoughts - this is the pump leather being "too good". It is not allowing the air to pass over it on the way up - so leaves a vacum. Nothing to worry about as long as you can pump and get pressure. Unless you find green slime all over it that is..
I recently had the same problem, I cured it by removing the extra washers that were holding the leather firmly against the backing plate and making sure that the slot in the nut was facing the one remaining washer, this left a little free play to allow air through when the pump was on the upstroke but sealed under pressure i.e. when the pump was on the downstroke. Another possible cause could be the leather is too thick; can you guarantee the pump leather is a genuine Bialaddin part ?
@Henry Plews Yes, its a genuine leather from a fettling kit. I'll sort it when I get the chance, and let You know whats causing it.
So I experimented and put a larger washer under the nut, and as Henry says - this stops the leather flexing properly and can create a vacum that draws the pump back down. (sad but it was a slow day) C
What you describe is how a pump should behave (it is only when you are actively pumping that the cup and seals on the down stroke) the up stroke should draw air past the leather cup or through the centre hole.
