Classic Whats this for?

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CCCars

Member
Posts
57
Location
Wales
On the drivers side of the plenum there are 3 vacuum connections, one for the brake servo and one to the extra air valve but whats the one in the middle for? 1986 RR Vogue EFi, I've replaced all the other vacuum hoses but can't find what this one is for.
Also the stub on top of the throttle body is almost rusted away any suggestions for making good, looks like the steel pipe has acted like a sacrificial anode!
Thanks
Graham
 
I'd guess either cruise control or some of them have a vac operated flap for the heater recirc/fresh air flap
 
Just had a look at mine - 1986 3.5 EFi auto with 4CU ECU & Flapper AFM.
I don't have air conditioning.
It did have a replacement engine, I believe around 1990 which was 4 years before I got it.

It's called the ram pipe housing & sits under the plenum chamber.
It has three openings on the right hand side, all of which are open into the plenum.

On mine:
The front one is for the extra air valve.
The rear one is to the brake servo.
The centre one that you're referring to is blanked off with a blanking plug.

The section of the factory manual - SRR660ENWM 'All petrol and diesel models 1986 to 1989' - that deals with removing the ram housing shows removal of the brake servo hose and removal of the extra air valve hose as it appears on mine but no mention of anything that would be connected to the blanked off one.
 
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Bit more digging through the supplements of the same manual shows 3 pipes present for 1988 MY with the Hotwire AFM & catalytic converters.
Doesn't say where they connect to though.
 
Without looking under the hood of my '87 (which is not at home at the moment) I'd say vacuum pipe for either cruise or fresh air flap on the heating. In either case there will be a black plastic ball underneath the air cleaner trumpet.
Not sure when air flap operation changed from a simple lever in the heater controls to the stupidly complicated electro-vac. operated system ... my June '87 has it & I bypassed said unit when it failed, just connected the vacuum tube direct. You can tell which system you have by the air-flap operating lever ... long travel (like a heat control) is mechanical, short throw (more like a switch) is the later device needing both power & vacuum, which is stored by the 'ball'
I
 
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The plastic ball rings a bell, it's a long time since I pulled the engine to build a LR/RR hybrid no A/C lol so I'll just leave it blanked!
Thanks everyone for your help.
Graham
 
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