Having a few little annoying faults with my 2007 GV at the moment....grrrrr

One problem I've noticed, after switching the engine off, I can hear a hising noise for about 15-20 seconds, then it stops.

I've reasoned that it's some kind of vacuum leak, because pressing on the brake pedal (ie operating the servo) when the engine's switched off causes the hissing to stop sooner. It's coming from the area to the right of the dipstick tube, there's a load of tubing/valves in that area, nothing obvious is damaged.

It's definitely a vacuum leak, because I've also noticed that after the hissing has stopped, the brake pedal is solid, just like the servo is exhausted.

It's probably leaking when the engine is running but I can't hear it due to the background noise.

Any ideas ???


After further reading on the forum, I think this could well be related to the EGR valve ???

Mat

cheers

 

Before switching off disconnect a vacuum line and plug it and see if the noise happens, keep doing it until you find where it's coming from. Though a good place to start would be the throttle valve actuator which is part of the EGR system (on the aluminium intake pipe) . But be methodical to be sure

Richard

 

Hi thanks for the info. I worked out that the leak seemed to be coming from the little 3 port vacuum valve that controls the EGR.

I took it off cleaned it with brake cleaner and then WD40, reconnected it and all seems well.

If I disconnect the white connector at the top port, I get engine vacuum sucking from that pipe, When I reconnect it all, on starting the engine the EGR valve is at it's spring loaded rest place, then when the air con clutch engages about 20-30secs after starting, the EGR valve moves about half way.

On switch off, there's no more hissing.

The bottom port on the switch has a little black cap with foam in. It doesn't look airtight, but I'm not sure if it's supposed to be ???

Mat

 

The foam will probably be the air filter. For a vacuum valve to operate air has to get in to operate/open a component and be sucked out (via vac pump) to close a component. Or vice versa of course. So the vac leak that you heard was possibly the valve sticking and not releasing quicky when engine shut down. Dump the Vacuum it's called in vacuum brake systems.

 

Was just thinking about this valve, how do we know if its working right or slightly working. As far as I can see it gets its Vacuum from the servo and the valve operates the EGR whether with spurts of Vacuum, full Vacuum or none at all.
So if it leaks in Margriff's case, EGR operation may be questionable.
Might be a good idea to remove the valve and test its operation for sealing the ports with the required voltage. Is it 12v or 5v methinks, might be labelled.
Tfb mentions a throttle valve actuator which could be on the line but I've no info on this as pipe goes down back of engine, but need to clarify this.

 

I could tell mine was leaking as it hissed for about 30secs after switching off the engine.

Also I noticed that the brake pedal felt a bit hard at low speeds... which I know now was due to the vacuum leak affecting the servo. I've only had this GV for a couple of months, so I could tell the difference with the brake compared to my old 2001 CRD.

Now that I've fixed the vacuum leak from the valve the brake pedal feels good again, with more stopping power for less effort, and the hissing has now stopped.

I've just been busy sorting out the usual issues that voyagers have such as the handbrake.... linkages were seized and shoes worn down.

Mat

 

I was wondering how much vacuum you were loosing and it goes to show your valve was leaking all the time and not just when switched off. So your EGR wasn't working at all and vacuum pump was toiling to supply servo.
My handbrake is all sorted now, new cables, discs, pads, shoes and mod to shoe retainers. Backplate dust shields are rather rotten but at about £100 each they'll do another year.

 

PART No. K05149105AA £25+vat from main dealers