Hi guys - a quick question for you 348/355 owners. 348 cars, and first year 355s came with the teves abs system. It uses an accumulator to store pressure so the pump doesn’t need to run continually. anyway, this accumulator runs some pretty serious pressure that is retained for a few days after the car is turned off. It can be manually depressurised by pumping the brake pedal once the car is powered off.. so my question is (and yes I’m anally retentive), is it a good idea to pump the brakes to depressurise after a drive if you intend on not driving the car for a week or so? I’m thinking not having to hold pressure for a few days might help with the life of the accumulator. I realise this means the pump needs to repressurise from nothing, however since the car was going to sit for a week anyway it would have been fully depressurised by then anyway. What say the gurus? Do these accumulators need replacing often enough that they deserve this kind of consideration, or am I more likely to kill my master cylinder with all that pumping.. thanks chaps.
I personally wouldn't worry about it. Those accumulators were designed to be at constant pressure and are found on tons of other cars most of which are not sitting for any length of time.
I think it should be left to depressurise slowly by itself. Depressurising by pumping causes rapid flexing of the diaphragm which may shorten its life (well, it's one possible theory).
If the key is off, pumping the brakes will reduce the pressure in the accumulator. It's no different that pumping the brakes with the key on, until the pressure drops to the point where the pump would kick in. With the Teves system the rear brakes are controlled by the accumulator pressure even when ABS is not activated. When the brake pedal is depressed the high pressure fluid from the accumulator feeds the rear brake calipers to apply rear braking. When the brakes are released the excess fluid from the rear brake system is feed back to the reservoir. Thus the pressure int he accumulator circuit is reduced. But there is no need to do so when shutting down. The accumulator does not need service unless it fails.
