Buzzing noise when turning ignition off after driving

[ianevans]

2007 California 79,000 miles on odometer.

When turning ignition off, there is usually a buzzing noise coming from the front. It seems to last a couple of minutes and then fades away. Does not always do it, but seems to be getting more noticeable.

Another issue, maybe not linked?

After taking the van out of storage this spring. Sometimes when I turn the ignition key nothing happens. If I turn off, withdraw the key and start again it seems to start OK.

We are touring Europe and concerned that these issues may get worse and cause us a breakdown. Any ideas? I am prepared to go to a VW dealer if necessary.

So far neither issue has stopped us and camper runs as well as ever.

Thanks, Ian

 

[kurienp]

2007 California 79,000 miles on odometer.

When turning ignition off, there is usually a buzzing noise coming from the front. It seems to last a couple of minutes and then fades away. Does not always do it, but seems to be getting more noticeable.

Another issue, maybe not linked?

After taking the van out of storage this spring. Sometimes when I turn the ignition key nothing happens. If I turn off, withdraw the key and start again it seems to start OK.

We are touring Europe and concerned that these issues may get worse and cause us a breakdown. Any ideas? I am prepared to go to a VW dealer if necessary.

So far neither issue has stopped us and camper runs as well as ever.

Thanks, Ian

Ian, the first thing that comes to mind, especially for the delay in starting / turning the key twice will be a starter battery on its last legs. won't worry me as long as I have Europe recovery. AA or similar can replace the battery from their van stock.

The noise when you switch off the engine could also be related.

Sent from my Pixel 6 Pro using Tapatalk

 

[2into1]

I think this is going to be related to the n75 moo valve, but is normally discussed on later vans. My 2006 does it too, so following....

 

[ianevans]

What is an N75 Moo valve? Ours is a LHD also.......

I note the comment re battery. It is not that old, but I may be surprised.

Thanks, Ian

 

[2into1]

It's one of the electronic and I think vacuum control valves, mounted near the top of the engine bulkhead (near the wiper mechanism. Google or the search here will tell you more, though most of the chat here has been on T5.1s.

 

[B J G]

N75 referred to as the Moo valve only makes the sound for a second or two. Quite loud and gets its name from sounding like a cow moo.It controls the EGR valve (exhaust gas recirculation).
Don't think you have that issue.

 

[WelshGas]

N75 referred to as the Moo valve only makes the sound for a second or two. Quite loud and gets its name from sounding like a cow moo.It controls the EGR valve (exhaust gas recirculation).
Don't think you have that issue.

Are you sure?




What is the N75 Valve? The N75 valve is a fundamental part of controlling boost on a engine. Its a small electronic solenoid valve that the ECU regulates to control how much boost the turbo has to create.

 

[B J G]

Are you sure?


View attachment 106990

What is the N75 Valve? The N75 valve is a fundamental part of controlling boost on a engine. Its a small electronic solenoid valve that the ECU regulates to control how much boost the turbo has to create.

I had the Moo noise on my T6 intermittently and it would loose the vacuum pressure very quickly, hence the so called Moo noise.

Best check is to get someone to turn engine off whilst listening with bonnet open to isolate noise origin.

I've no idea as to what is normal on a T5 but my T6 and car both have noises like something running after ignition switch off which I assume is an electronic shut down process.

 

[steveball1969]

What audio system do you have? We have a 2012 Cali with the Dynaudio package. Crucially that as an additional amp under the driver's seat (RHD). It stays on for several minutes after the ignition is turned off and key removed. A prev owner had fitted a VW RNS510 stereo, but it was not coded to tell it about the additional amp and buzzed for several minutes at startup. Also, even at very quiet settings on the head unit, the audio was too loud. Essentially, the audio output from the head unit is reduced to account for the additional amp when coded (I used VCDS).

The other problem could be many things - a dodgy key switch, bad battery, bad starter or starter relay/solenoid, but are you waiting for glow plugs to heat up? If not, it could be as easy at that. Wait for the amber coil light on the dash to go out before cranking.

 

[Red wine lover]

We had to replace our moo valve. Then I was worried because the fan kept going after I switched off....the heater was on, so it works! We had never used it before and when putting the control panel back in after repair I must have pushed the button.
Just spent time putting up our driveaway - decided not to make prats of ourselves on site, the first time using it. We use the safari room on our weekend trips.

 

[Lambeth Cali]

N75 referred to as the Moo valve only makes the sound for a second or two. Quite loud and gets its name from sounding like a cow moo.It controls the EGR valve (exhaust gas recirculation).
Don't think you have that issue.

Mine has started doing this. Quite loud. A mechanic was fixing something else recently and I pointed out the noise and he seemed to think it was normal.
So is it ok if it makes a loud noise?

 

[ianevans]

I am having mine fixed tomorrow. Mechanic said not a huge deal and can drive without, but I am replacing. Looks like just under 200 pounds with parts and labour.

 

[WelshGas]

Mine has started doing this. Quite loud. A mechanic was fixing something else recently and I pointed out the noise and he seemed to think it was normal.
So is it ok if it makes a loud noise?

Frequently it's the small vacuum tubes that plug into the valve that wear and start leaking. Apparantly they were modified some years ago for this problem.

 

[Lambeth Cali]

2007 California 79,000 miles on odometer.

When turning ignition off, there is usually a buzzing noise coming from the front. It seems to last a couple of minutes and then fades away. Does not always do it, but seems to be getting more noticeable.

Another issue, maybe not linked?

After taking the van out of storage this spring. Sometimes when I turn the ignition key nothing happens. If I turn off, withdraw the key and start again it seems to start OK.

We are touring Europe and concerned that these issues may get worse and cause us a breakdown. Any ideas? I am prepared to go to a VW dealer if necessary.

So far neither issue has stopped us and camper runs as well as ever.

Thanks, Ian

Our 2008 needed a new starter motor a couple of years ago. Same symptoms. Seemed to be a common problem with that age of van.

 

[Lambeth Cali]

Frequently it's the small vacuum tubes that plug into the valve that wear and start leaking. Apparantly they were modified some years ago for this problem.

The other problem was the air pipe going to the turbo coming off leading to our breakdown in France. I wonder if related. Perhaps the pipe was lose and had been leaking.
Anyway probably getting serviced before the summer holidays so at least I can suggest they check it. It is definitely a lot louder than before.

 

[Elmo3]

Mine has started doing this. Quite loud. A mechanic was fixing something else recently and I pointed out the noise and he seemed to think it was normal.
So is it ok if it makes a loud noise?

Replace it. I changed the moo valve (N75) on my previous T5 myself. Very simple job, OEM part about £40 IIRC.

 

[ianevans]

Update from Ian (original post).I just had the problem fixed. The parts needed were a "Converter" and "Air cleaner", parts cost 104 pounds and about 45 minutes of labour. Noise stopped immediately and has not come back. Engine seems quieter, but may be my imagination!

Ian