Loud whistling noise from the rear of the engine
 

Two weeks ago, after waking my ZT from hibernation, I noticed a strange loud whistling noise coming from the engine area.
It occurs everytime I press on the gas pedal, but especially on load, no matter if its high or low. And it's whistling until i take my foot of the pedal.
If I break with with the engine, no matter how much rpm, I can't hear anything.
I even tried to turn of the engine of at higher speed in gear and there was nothing to hear. but when I pressed on the gas pedal an the throttle body opened, the noise was back. Not as loud as on running engine but definitively audible.

I suspect that the noise occurs when a certain amount of air/exhaust is flowing through the engine. The more flow the louder the noise.

Searching on the internet and especially in this forum I read a lot about broken or loose breather pipes.
So I checked all breather pipes and even opened both valve covers to check if there was something blocked. In fact the small hole on the rear valve cover was clogged but cleaning it didn't solve the problem.

I tried to figure our where it comes from but it's hard to locate. It seams like it's coming from the rear bank.

I have no idea what causes this noise.
Did anybody have this problem?

I found an old video on youtube which shows exacty the same problem I have. https://www.youtube.com/watch?v=0aPFrq0f8MM

Compression checked
 

Yesterday I took of the inlet manifold to check the compression in all cylinders. I was scared of a burned valve.

But the compression I measured was between 12.5 and 13 BAR in all cylinders. So the valves should be fine.

During the last weeks I noticed that the whistling noise appears a little bit earlier each time.

Might this noise come from the exhaust system, especially exhaust manifold?

Did anybody have a similar experience?

Greatings
Martin

This sounds the same problem you have - the IMG is mentioned but also an air/ vacuum leak .
:shrug:

https://www.mg-rover.org/threads/ver...histle.349599/

I found this thread a while ago when trying to help a friend with an MGF resolve a similar issue - his was indeed a very old (possibly original) IMG however on the K Series it's quite a different design (I am assuming you have a V6).

It could also be the exhaust manifold gasket - higher gas pressures at high RPM could be allowing a small leak to slip by.
Check for any carbon deposits around the exhaust manifolds, it should be easy to see if this is the cause of the problem. If it is we have them here: https://www.dmgrs.co.uk/products/kv6...-all-v6-models