Whistling 202

[VK SL 3800]

Now that its winter again my 202 has started to whistle randomly, it only does it in the cold weather and only after the engine warms up a tad, will come and go randomly but then goes away after for good about 15-25 minutes driving depending on the temperature. Is really inconsistent, it will whistle after you accelerate giving low vacuum on the manifold and then back off or be on the overrun pulling high vacuum but wont whislte all the time /every time, does it best when you go over a steep hill, it will whistle until about halfway down the other side then slowly get quietet and then stop even though the amount of manifold vacuum is the same (i have an economy gauge still).
Removed the line for the dash controls, air pump diverter, replaced the PCV valve, disconnected the economy gauge, gone over my vacuum lines about 100 times and found nothing, no cracks splits ect.
Really hard to track, if you get it to whistle then pull up, by the time you get the bonnet open its gone.
Idle is consistent and smooth, fuel economy is fine, manifold bolts are tight.
Any ideas on what part would cause such an awesomely annoying noise?

Vac diagrams are on Scott's site
VK Berlina Project

[commy vk]

Checked YR alternator?

[VK SL 3800]

Did have it apart a year ago to put new bearings in it but its not rev related and cant get it whistle by reving at idle while your under the bonnet so i doubt thats it.

[GenReaper]

Pretty sure they run an EGR diaphram and that could be split.

Pull off the line to the EGR and plug it and if the noise goes away there is your problem.

[VK SL 3800]

Yeah ill do it tomorrow morning, if it not that its got to be diaphragm somewhere........ they have quite a few around the place.

[TheIceman]

ive seen a few whistling commodores of this model, pour a bucket of water over the manifold when its whistling if ya can and see if it dissapears, maybe an inlet manifold air leak as well.

[ari666]

TVS leaking. i reckon you may find a hairline crack in it.

[vk.jonno]

TVS leaking. i reckon you may find a hairline crack in it.

And here I was thinking u were gonna say something
Like "that's cos it's a 202, get a 308 and it'll stop"
Hahaha

[GenReaper]

Let us know if the EGR bypass stopped the noise ?

[VK SL 3800]

Well EGR wasn't it, little throttle nudger thing wasn't it, all the air pre-heat system wasn't it. Couldn't find any leaks in the manifold gasket but not to rule it out all together as it could be leaking from the bottom.
So TVS sounds like a good one, most likely the one that operates the vacuum to the little flap in the exhaust actuator as i discovered the EGR valve doesn't get any vacuum at all at idle an on overrun and thats what the other TVS is for. Makes sense, wont whistle when cold cause thats open but when it closes the vacuum is drawn through crack then when engine get fully warm plastic expands then closes up the gap. Will give it a go anyways......

[Project_HR]

maybe it is a happy little 202 ..... I sometimes whistle when I am happy .....

[VK SL 3800]

Lol it might be happy but its driving me mad!!!!

[GenReaper]

One good way to find vaccuum leaks tho not recomended...
Get a bucket of water or fire extinguisher for safety.
Put some petrol in a tin and use a paint brush and dab the paint brush in the petrol and then dab it around the intake manifold and any accesories that run off the intake manifold.

If it picks up RPM then you know you have a leak in that particular area.
I cannot hense the safety in doing so, but it does work, an old mechanics trick.

If you do this just be carefull and using little on the brush at a time to reduce the possability of a fire.
Best do it when cold engine as to not spill any on a hot exhaust manifold and obviously keep it away from ignition leads.
If it doesnt pick up RPM on the intake manifold its possibly the exhaust manifold ports leaking or possibly even a cracked exhaust manifold.

Just something you could try but be carefull when doing so.

[VK SL 3800]

Ok, today disconnected the TVS on the way to work and it didnt fix the problem, so after work drove it in the shop and had another look over everything, i found 1 loose manifold bolt, the one right at the back.... i missed it before cause it was dark and assumed that it was like the red motors i had always played with and just had a stud with no nut. Wrong! Tightened him up and drove home and so far havent heard a peep out of it, so fingers crossed!

If it still whistles i will go for your approach GenReaper. Thanks all for your advice.

[ari666]

nice!

i love when stuff gets fixed

edit* even if i was wrong

[TheIceman]

If it still whistles i will go for your approach GenReaper. Thanks all for your advice.

ive seen a few whistling commodores of this model, pour a bucket of water over the manifold when its whistling if ya can and see if it dissapears, maybe an inlet manifold air leak as well.

yep, i was right though, ive fixed umpteen number of whistles by tightening manifolds on those comomdores and most diganosed by the bucket of water. never have i used petrol, i have heard of it, but water does similar trick, u will notice engine change as soon as water gets sucked into a small hole.

[VK SL 3800]

ive seen a few whistling commodores of this model, pour a bucket of water over the manifold when its whistling if ya can and see if it dissapears, maybe an inlet manifold air leak as well.

Never got a chance to use the water trick while it was whistling as it never whistled at idle, it would only for a few seconds after you pull up and i would hop out and try to find it, by then it would be gone , but shes all good now!