(Home) Vacuum (and similar) Pipes (Print)

A couple of months ago, I was asked what pipes go where. Let’s face it, get that engine cover up and it’s a plumber’s nightmare under there. So I took a photo and set about tracing what goes where, based upon the assumption that everything on mine was working correctly so it must be right (touch wood). Mine is a CR30 4WD model. A, B and J are vacuum valves operated by electrical solenoids. They each have 3 ports. Which of the other 2 ports the "common" port is internally connected to depends on whether it is electrically energised or not. The bodies of these valves, and particularly the ports on to which the pipes push, are quite fragile. Be careful.

J controls the Exhaust Gas Recirculation (EGR) K by a vacuum operated diaphragm.

J has pipes pushed on to two ports close together on the left hand side. The pipe from the "common" port on J connects to K with a pipe that has what looks like an in-line filter. When unenergised the valve connects that port to the atmosphere through the black cylindrical vent cover pushed on the right-hand end of the valve. When electrically energised the valve connects the "common" port to the one on the extreme left which is the vacuum "supply" from L (a thin plastic pipe that runs over the front of the engine and under the driver's seat and connects to the vacuum pump on the front of the alternator).

A and B both control the idling speed. One from the Idle-up switch on the dash when the climate control is running, the other when the aircon compressor is running. The vacuum servo C alters the accelerator idling position at the side of the fuel injector pump, once the engine has warmed up.

The vacuum "supply" pipe for these, M goes over the engine with pipe L (and on to the dash?). M goes to 2 T-pieces and then into pipe N which runs to the back of the vehicle, down out of sight, (to the 4WD servo in the pillar behind the sliding door?).

A, towards the front, has 3 pipes and B towards the back has only two - B's unenergised port vents through a push-on cylindrical cover at the right-hand end.

1 connects the middle, "common" port of A to C, so that if A is energised C will be actuated by the vacuum supply into the "energised" port 2 which is joined to a T-piece that connects to the supply line M and N.
When not energised, valve A internally connects its "common" port 1 to its "unenergised" port 3 which is joined to the "common" port of valve B via pipe 5.
When valve B is not energised port 5 is vented to the atmosphere. When it is energised 5 is connected internally to 4 which is the vacuum supply again, joined to another T-piece that connects to M and N. So, when valve B is energised but valve A is not, vacuum reaches C via M-4-5-3-1.

Pipes which are not Vacuum Pipes!

D has two pressure switches underneath, for the turbo pressure indicators on the dash. Two pipes coming from these join into a T-piece and onto the pipe E. E connects to a T-piece F. F connects to H to pick up the turbo pressure in the air pipe from the turbo to the inlet manifold.
F also connects G on top of the injector pump where turbo pressure pushes a diaphragm down to control the fuel pump.

The thick cable at the bottom left of the picture is the Hi-Lo gear shift cable (4WD only)

Ian Dunse, April 2002 (with additional detail by Dave Mason, July 2002)