Hi all... I'm currently restoring my first bus and always thought the brakes were rather heavy, but now I know why... I've just realised that the pipe in the wheel arch beneath the driver's seat is the vacuum pipe to the brake servo. Trouble is... it's been cut off (see photo below, with cut end arrowed). The PO has added twin Weber 34 ICTs so I don't have the original air cleaner, which is where I guess the pipe would have ultimately connected. Can anyone advise how this pipe gets from the wheel arch to the engine, and where it should connect, given I have twin carbs? It's a 2l type 4 engine. Thanks all.
the pipe only runs under the arch as it is, it runs into the back of the arch but its just an air inlet but it should run into the triangular part at the back of the arch, near the seatbelt mount
I guess that was a numpty question, Davidoft, but thanks for the rapid response. Time for numpty question number two then... The Bentley manual refers to 'a check valve installed in the vacuum line from the engine to the brake servo vacuum chamber'... I can't find this pipe anywhere... any clues? Where should it connect in the engine?
The pipe in pic is just a breather so the servo can equalise, but like it is water will get in and knacker your servo. It needs extending to the arch. Any old flexible pipe will do as there is no vacuum in this pipe. From inlet manifold through tinware, through one-way valve and on to the servo. Get underneath, you can't miss the big ugly thing.
Thanks Zed... I think I'm going to have to remove the servo to clean it as I think water may already have got in... it feels like there may be rust beneath/within the rubber boot. Also... I can see the vacuum pipe from the servo which leads towards the back of the bus, but there's no pipe in the engine bay, so am not sure where it should connect to... presumably one of the inlet manifolds?
Yes one or both of the inlet manifolds. Get it tapped and connected and your brakes will improve, assuming the servo isn't already knacked.
I had two tiny 3/4mm ones on mine for a balance pipe and joined into that. I didn't think it would be enough, but trying it saved a whole heap of hassle and it works a treat. It's prob too small for a balnce pipe though, but the bus goes ok.
Don't suppose anyone has any photos of their manifold vacuum connections, especially for a balance pipe?
I replaced the standard carbs with 34 ICTs ,the manifolds are tapped 3/8 bsp, this is easyest size to get suitable hose barb's to attach a balance hose, which i put a tee into and attached the servo hose. this just replicate's the original steel balance pipe, i used 8mm hose and like Zed said i thought it might be too small but works perfect. I was also advised by a reputable engine builder that a balance pipe helps a lot with smooth running.
Balance pipe makes balancing carbs a bit more forgiving at tickover, not sure if it's much help otherwise.
