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Garage => Mechanicals => Topic started by: daantjie on 17 February 2023, 11:53 AM

Title: Vacuum check valve musings
Post by: daantjie on 17 February 2023, 11:53 AM
Hi guys

I have been experiencing loss of vaccum on my door locks whereas before it would hold vacuum for months.  I traced it down to the "secondary" check valve under the dash behind the cluster, the white/black one, part number 1238000078.  So I was wondering why we have this type of check valve in there as opposed to the blue/black ones, part number 1168300078?  These ones you will find all over the car, mostly you will see them in the engine compartment if you have the US spec ACC system, also they use them downstream in the ACC system as well.

Not sure if all 116's had this check valve in this location.  Also I think there might have been a supercession from the 116 to the 123 number.  I am pondering why this was done.

Anybody know why you cannot just use the blue/black ones under the dash?

Pics attached.

Cheers
[attach id=13733]1238000078.PNG
[attach id=13734]1168000378.PNG
Title: Re: Vacuum check valve musings
Post by: daantjie on 17 February 2023, 02:56 PM
Just to add some context, here is a pic from one of Robert's (rumb) earlier posts:

Title: Re: Vacuum check valve musings
Post by: rumb on 17 February 2023, 06:28 PM
I would suppose the insides are different and the behave differently.
Title: Re: Vacuum check valve musings
Post by: daantjie on 18 February 2023, 01:36 AM
I might have to do an autopsy on the old unit to see what is what.
Title: Re: Vacuum check valve musings
Post by: raueda1 on 18 February 2023, 10:16 AM
Quote from: daantjie on 18 February 2023, 01:36 AMI might have to do an autopsy on the old unit to see what is what.
I eagerly await your findings.  Got a similar problem.
Title: Re: Vacuum check valve musings
Post by: daantjie on 18 February 2023, 04:16 PM
OK, time for show and tell kids ;D   I had to cut them open with my Dremel, they are very well stuck together, obviously as they need to be air tight.  The black/blue one seems to be more robust, with thicker vacuum diaphragm as well as a return spring of sorts.  The black/white one has a very thin diaphragm and a completely different design.  I know nothing of vacuum and such, so not sure what you guys make of this?

Title: Re: Vacuum check valve musings
Post by: rumb on 18 February 2023, 06:42 PM
To late now but measure vac to open each one. Maybe top one is more of a regulator?




The top one  1238000078 is avail from dealer so just buy new one?
Title: Re: Vacuum check valve musings
Post by: daantjie on 18 February 2023, 09:24 PM
Yup I've got a new one on order.  I'll compare once it comes in.
Title: Re: Vacuum check valve musings
Post by: Jenno1981 on 15 March 2023, 10:48 PM
This was a timely post for me. I was making an attempt at diagnosing my central locking (or lack there of...) and located a broken Blue/Black.

Apart from the dealership, anywhere is Australia that would have these? Tried Bursons and Rare Spares but only got strange looks 🤷�♂️

Any local ideas?