Re: [T3] Power Bleeders

[Jens Vagelpohl <jens@type4.org>]

<x-flowed>Speaking of power bleeders, I was faced with trying to use one today.  
On my 412 wagon one caliper had a stuck piston so I needed to  
overhaul it.

Side note for people wanting to rebuild theirs: The 412 has an ATE  
unit with a piston on each side of the caliper, I do believe (but am  
not sure) the Type 3 uses a similar or maybe even same unit. Since  
original rebuild kits for the 412 were no longer available (surprise  
surprise) I ordered a kit for the ATE caliper found on Super Beetles.  
The main piece, the sealing ring, seems to be the same. The outside  
rubber seal seemed a tick short as far as possible outward piston  
travel goes, but it does fit. The only item not fitting at all was  
the metal plate that is supposed to prevent the pistons from turning,  
so I re-used the old one.

Anyway, I was faced with a really modern bleeder that works by  
pumping fluid at pressure into the overflow container or,  
alternatively, by applying suction at the bleeder nipple end. Putting  
pressurized fluid into the system did not work because the cap with  
inlet I used was home made (none of the "real" adapters fit) and  
leaked fluid. The suction method worked, but unfortunately it was  
impossible to tell whether the air in the clear hose from the rubber  
suction adapter on the bleeder was from the brake system or from the  
fact that the rubber adapter really did not seal well enough (or  
maybe sucked in through the bleeder threads). So I resorted to a very  
simple method that does not require any fancy bleeder: Using the same  
home-made cap with inlet-adapter that leaked pressurized fluid, I  
simply connected pressurized air that came through a pressure  
regulator which limited it to 1/2 bar. Easy-peasy after that, you  
just need to watch the fluid level to make sure you don't end up  
pushing air into the brake lines.

jens

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