Virage – fixing cracked vacuum pipes

As mentioned in the engine overview section, the most frequent and intractable problem with the Virage is cracked pipes in the vacuum system.  The engine management system depends on a consistent and full vacuum from the manifold being maintained.  There is a rats nest of piping between the manifold, the absolute pressure sensors, the fuel pressure regulator valves,  and the vacuum chamber for this system, all of which depends on a solid vacuum.  However the old polyvon tubing is now perishing on almost all Virages, and this leads to erratic running and sometimes complete engine stoppage.  The pipes move and expand as the car warms up and is driven, and this accounts for the inconsistent and unpredictable behaviour of the car, which has driven many owners (including us) to distraction.

No Aston main dealer or specialist we have seen has ever even mentioned this problem, let alone offered to fix it. And part of the problem is that replacing the pipes is a complex and long job (that took G*rry over 16 hours).  Plus there is no general parts manual or ‘how to’ guide to help you.  This page offers all the info we have gleaned on the process.  This includes schematics of the plenum chamber assembly and a schematic of the pipe layout, a reasonably detailed description of where the schematics differ from reality and a description of a novel method of fixing two of the critical pipes that does not involve removing the plenum chamber.  So here it all is. In almost every case, right click the link and select ‘save link as’ to download.

1. Schematic of vacuum pipe layout.

2. Description of actual pipe layout

3. Keyhole method of replacing two vacuum pipes

4. Steps in removing the Plenum Chamber

5. Plenum Chamber schematic

6. Plenum Chamber parts list
























Virage – fixing cracked vacuum pipes — 4 Comments

    • Hi Nick – it’s primarily because ECUs depend on the vacuum system including the pressure and lambda sensors to adjust the mixture and timing. If those results are incorrect or variable, the the ECU fails to work properly. Variable amounts of leakage in the vacuum system will affect those readings markedly. At cold the gaps in the pipes are probably at their widest, i.e. leaking most. They may close up as the engine and tubing heats up, but then may variably open with movement or vibration. Because there are separate ECUs for each bank the problem is probably exacerbated. Thus seems to be borne out by experience – all our timing and misfiring problems disappeared when the pipes were fixed. It’s fair to say that we still got some problems after that which G*rry traced to relays, but they were more binary in nature and not related to the engine temperature (or at least to cold starting).

  1. Great web sight and first thing I did with my Virage Barn find purchase, was replace all the vacuum piping and drained fuel tank removed both water and large quantity of Alloy oxide Crystals that were blocking the in-tank filter However, Items 32 & 34 do exist on my car (1991) also, the pipe that connects to the underside of the vacuum valve item 30 and I believe splits into 2, 1 each going to the Air Pump valves that run along between the bulkhead and engine is not discussed, there are also similar pipes that I replaced that went through either side of the bulk head and controlled the AC flaps these were only perished in the engine bay side.

    Mark T

    • Mark – Sorry for long delay in replying. First of all congratulations on owning a Virage and on fixing the pipes! On your comments, I wanted to get up to the Virage and investigate. It seems that on our model and possibly up to around chassis number 90, there is a direct t-piece at the vacuum valve instead of a connecting pipe and a separate t-piece. I have altered our description to cover that, and have also included a description of how to get the Plenum Chamber off, and a bit of further information on the heating/AC pipes. No further help to you as you have already done the job, but may help others with the problem. Best of luck for the future with your Virage!

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