BMW 4.8 V8 vacuum issues?

[NDA]

I have this engine - although not in a BMW.

When the car has been driven hard, the engine makes a sucking noise when tickling the throttle... it also starts with an even bigger ‘roar’ when started.

I have no idea if this is a vacuum leak from somewhere or from the manifold... it sounds like the top end front of the engine.

Today it’s behaving totally normally.

Odd.

Any thoughts from those that know this engine?

[naturalaspiration]

There are many places it can leak from, once over certain age, best to use a smoke machine to find which one it is.

You might be lucky...
https://www.bimmerforums.com/forum/showthread.php?...

Also I would go for a lower temp thermostat, BMWs high temp one is a cause of many issues on that engine, due to premature ageing all all rubber and plastic parts.

Edited by naturalaspiration on Tuesday 6th August 20:47

[NDA]

I will check that out - thanks....

[pits]

If you can't access a smoke machine, what you can do to find a vacuum leak is spray each vacuum pipe individually with WD-40, when it finds the leak it will seal the hole briefly and fix it.