Type 44 Vacuum Reservoirs WAS Diff locks color tubing decoded

[Huw Powell]

>>* Just what is the blue tank seen by the front left passenger door
> 
> *>* behind the hinges?
> 
>>When I first got my '89 200, I thought it was the "bomb", but I was
>>told it was a vacuum reservoir, for the door locks.

Well, someone was half right... it's a vacuum reservoir, but not for the 
door locks.

> I'd like to get this particular bit of errata nailed down now.  The blue,
> bulbous tripartite container behind the LF fender is a vacuum reservoir that
> connects to the dashboard vent (climate control) system.  There is a second
> vacuum reservoir, smaller, a single chamber, attached to the differential
> locking system in the trunk.  Is this correct?  I don't know why the car
> would have a vacuum reservoir for the door locks when it has a completely
> separate system with a dedicated pump, but maybe I'm wrong.  The climate
> control diagrams in my Bentley show the blue bulby thingy behind the LF
> fender as being attached to the intake manifold vacuum through a check
> valve.
> 
> So unless I'm mistaken, there are three separate vacuum systems, two of
> which have reservoirs:
> 
> 1) For the climate control system, with the blue reservoir behind the LF
> fender
> 2) For the differential locking system, with the smaller reservoir in the
> luggage compartment
> 3) For the central locking system, which doesn't have a reservoir per se,
> because it has a pump

Correct, the only cars I have seen with a "reservoir" attached to the 
locking system were two door models, I suspect it is just there as a 
buffer since only 2 (instead of 5) servos have to be opened or closed.

> Oh I forgot Vacuum System #4:  Cruise Control, which also has a dedicated
> pump.

And, of course, no reservoirs either.

> So by my tally on my '87 5KCSTQ, there are four separate vacuum systems that
> are not directly engine-related (i.e., leaving out the wastegate plumbing
> and connection to the ECU) and two electrical vacuum pumps -- one for the
> cruise control and one for the power lock mechanism.
> 
> Is that a fair statement?  Or am I all wet (or just sucking?)  ;)

Seems about right to me.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/