Buzzing from cam reset valve/solenoid.

[jh_rams65]

I've got my 04 XC70 in the garage after dealing with misfires on cylinders 4 and 5 per vida. Currently waiting on new coils and spark plugs since the plugs were quite worn.

Anyway, I've noticed for a while a buzzing from the engine compartment after it has been running and now that I have the engine cover removed I can pinpoint the buzzing from the cam reset valve on the exhaust side of the engine. It stops after a minute or two, but I'm wondering if this is normal or if I might have a faulty solenoid. Per vida, I pulled it off and the air passages seem to allow passage of air and there was no noticeable sludge. I didn't test it on 12 volts to verify the solenoid itself, but I'm more interested in whether this is normal buzzing or something I should troubleshoot more.

I've searched all over to find a similar situation but the only other symptoms I've read about include a ticking sound, and this is a definite buzz.

[Astro14]

OK, I'll bite...

Just what is a "cam reset valve"??? got a picture?

Are you sure it's not the Turbo Control Valve? That's a solenoid, that buzzes...over by the air cleaner...

[jh_rams65]

In the middle of the pic, those sensors/solenoids attached to the coils just to the right of the timing belt, that is referred to the cam reset valve in vida. There is an intake and exhaust side solenoid. The one on the exhaust side is the one with the high pitch buzz after the car has been shut off. I can't tell if this makes that's noise when it's running.

[Astro14]

Ah...OK...I know that one as just the VVT solenoid...and I haven't heard it buzzing on my car...and I am at a loss to explain why the solenoid would buzz...it should click..and it clicks open at a particular RPM/manifold pressure...whatever the ECU is programmed with...

I thought this was electrically actuated and oil pressure operated...so, air passages? you mean the oil passages?

Here's an off the wall question - what are you running for engine oil?

Reason I ask is that they can get sludged up and cause sticking...while you might not see the sludge per se, it could still be in there...my oil recommendation is Pennzoil Ultra, Platinum, Mobil 1 0W40 or HM 5W30, all for their cleaning agents...

[jh_rams65]

Yes, the oil passages, I referred to it as air since vida recommends making sure air can pass between the passages. As far as oil, I'm running Castrol full synthetic 5w-30.

If I unplug the vvt, the sound stops but starts as soon as plugging it in again. Therefore there must be a voltage going to it and perhaps it is supposed to be in a position that it's unable to do so.

Looks like I might have to do a voltage test on it to make sure the solenoid is actually working.

[jh_rams65]

Voltage tested the solenoid tonight and it does click such as a solenoid should do. I'm ruling out that the vvt is bad. I haven't a clue as to why it would be making such a noise after the car is shut off. I would assume once the car is turned off, that there should be no voltage going to the vvt whatsoever.

I can only assume that there must be a short or open circuit allowing voltage to still carry to the vvt after the car is shut off.

That is unless someone else can shed some light onto what would cause this issue.