jchasty

Hi All

It's been a long week, can someone please remind me what this part does?

It's either leaking or doing what it should - it's kinda whistling at idle!

Thanks

John

rbrtmchl

Here is a good thread to review:

https://rennlist.com/forums/928-foru...eon-an-s4.html

Mrmerlin

it would be beneficial to know model year you have,
and if the throttle shaft bearings/flappy bearings have been replaced

jchasty

Apologies. It's a 1990 S4.

What I can't see from the other thread is whether it should be "leaking" at idle?

Thanks John

FredR

John,

Idle pulls the deepest vacuum so more likely to whistle [leak air into the manifold rapidly] at idle than any other engine speed.

jchasty

Thanks Fred

Is the behaviour normal then? Air being sucked in at idle? Or is the valve faulty and leaking?

Cheers

FredR

John,

If there is a whistle then you have a leak and it needs to be addressed. It may not be serious or need immediate attention but it is not likely to get better by itself.

Are you sure the leak is on the flappy spindle? If so i doubt the problem can be solved with the manifold in-situ. You could squirt something like WD40 at the site to see if the whisling stops whilst the fluid flows

Irrespective, chances are whatever is causing the leak can only be resolved with an inlet manifold off job.

jchasty

OK thanks Fred!

Landseer

There's a Dwaynes garage write up where he did a pretty good job of tightening up the intake including seals for throttle body butterfly.

jchasty

Brilliant! Thanks!

Mrmerlin

based on your report the shaft bearings need to be replaced,
Roger has new double sided O ringed bearings you need 4 of them.
2 for the flappy shaft
and 2 for the throttle shaft.
NOTE the originals are single side O ringed bearings

jchasty

Thanks Mrmerlin - I'll email Roger