Whistling sound coming from rear

[73type2]

My ‘71 Beetle started to make a whistling sound. It goes away when accelerating, but returns when not. In reading some sources, this points to the clutch release bearing. Am I correct in my assumption?

[Dawie]

Faulty release bearing might typically make some noise when you press the clutch pedal.

If the return spring at transmission is not broken and pedal free play set to min 25mm... then there would be no force on release bearing when pedal not pressed. Should be quiet when not touching/turning.

Loose fan belt noise would be opposite as you describe- only scream while accelerating.

[73type2]

Thanks Dawie. I dropped the engine already, so I’ll make sure free play is set to min 25mm after installing everything. I’m in any case replacing the release bearing, just to eliminate that part.

[73type2]

I think you meant max 25mm.

[retrovan]

Think the whistle would be a hole in the exhaust or gasket

Herman

[73type2]

Thanks, Herman. I’ll check it out.

[73type2]

I couldn’t find any exhaust leaks, it sounds like the whistling comes from under the right hand valve cover. The other side is quiet. On inspection all seems in order. Could it be the rocker shaft?

[Dawie]

Whistling sound when not accelerating- (part load/high inlet vacuum). Whistling disappears when accelerating- low vacuum.

Maybe inlet vacuum related in that area?

[73type2]

Sounds worth investigating, Dawie. I’m pulling the engine again and will run it on my test stand for further diagnosis.

[retrovan]

Could be a head seal, if under the tappet cover.

Or your copper exhaust seal on your header J pipe.

Herman

[73type2]

Thanks, I’ll be sure to follow all suggestions when the engine’s out.

[Dawie]

You could use a small diameter flexible hose to better listen/pinpoint the source of whistle. Even while engine is still in car.

On righthand side (right when looking from behind), you can remove the right bottom plate for better access. Also listen around inlet manifold area.

[73type2]

I dropped the engine and had a closer look in the general area from where the strange whistling seemed to come. This is what I found:




It looks like some oiliness/wetness around no 1 intake. Maybe I found the source of my problem in the form of an intake vacuum leak.

[73type2]

Some feedback for the three people still on this site. I removed the engine and ran it on my test stand, after making sure there are no leaks. I must say it’s much easier to set valve clearances on the stand. I also replaced the main seal, just because the engine was out. It’s a good thing I did, because the one I bought from Flat Four Racing recently leaked. The Viton one I got from BMG was nearly four times as much, but is much better quality. The money spent on importing a Torquemeister paid off. Took the car for a test drive and all seems well, with no whistling, except the normal one from the pea shooters.