'Groaning' noise during certain areas of the rev range

[Sirocco20348]

Hey guys,

This is more of an annoyance than a problem.

As I accelerate through the rev range, at around the the 2100rpm and 3100rpm, I can hear like a groaning noise. ( 1st and 2nd gear)

If I hold the revs at the specific rpm it will continue to groan until I accelerate or brake out of that rpm.

I'm thinking its like a resonance frequency and its vibrating something??

I know this is so vague, but has anyone else experienced this slightly annoying sound??

[Sirocco20348]

Hey guys, I've progressed in finding someone else that is experiencing this problem. But the instructions are vague for someone like me who works better with pictures.

Can anyone recommend what I am moving and to where?

A4 FAQ: 1.8T Moan/Groan-Like Noise

Written by: Tom Fric in 1999
Please direct specific questions to the author!

There have been a significant number of A4 1.8T (with manual transmission) owners complaining of a moan or groan-like sound coming from the engine area under acceleration. The following symptoms appear to be typical:

1.Noise occurs between 2000 and 3000 rpm under slow and moderate acceleration.
2.Noise lasts for a short time - a split-second to a couple of seconds.
3.A slight vibration can be felt through the gas pedal or floor.
4.Noise tends to occur more often as the outside temperature is hotter.

This solution for this noise is known by Audi, but not all dealers appear to be aware of it. The noise is an acoustic resonance having to do with the turbo bypass hose system (similar to the noise you get when blowing over the top of a Coke bottle). The fix is to replace the bypass valve hosing and thereby change the placement of the bypass valve. Apparently the fix involves replacing the hosing of the manual's to that of the automatic transmission's. In three documented cases in A4.org, the following parts were installed during the fix:

•1 058-145-712-A Pipe
•2 N-024-504-4 Clamp
•5 N-101-965-02 Hose (in 2 cases), 1 N-101-965-02 Hose (in 1 case)
•2 N-102-581-01 Clip
•1 058-145-832-C Hose (in 2 cases), 1 4B0-145-832 Hose (in 1 case)
•1 035-133-989-A Adapter
•2 N-100-911-01 Clip

The occurence of this noise and its related fix have appeared on 1997 and 1998 model year 1.8T's.

[Sirocco20348]

I've been searching for a while now... anyone have a picture of what they describe as

Apparently the fix involves replacing the hosing of the manual's to that of the automatic transmission's.

Did the 1.8t audi's come in automatic aswell?

[Sirocco20348]

Hmm the location of the DV on the A4 is quite different.

[Sirocco20348]

I have read further that its the Diaphram in the DV that is resonating. Im running an old 710N DV that came with the car, so Im not sure how old it is.

I have a new 710N at home, so ill replace that tonight and see if that eliminates the noise. Otherwise ill just buy the Forge 007 which eliminates the diaphram altogether.

Ill keep everyone informed of this highly irregular problem that no one cares about

[Lito]

when i was running diaphram dvs (710n and Apr r1) i used to get a weird honking noise at 0psi would go away if you went back into vacuum or into boost. dunno if this is the same as your noise as you said yours is rpm related. i switched to a piston type dv and the noise disappeared. it literally sounded like there was a dying goose under my bonnet lol

[Sirocco20348]

Yeh LOL its sound like a goose dying under the bonnet... or chewbacca

It deadset sounds like this.... https://www.youtube.com/watch?v=ATpBFmRdfiQ#t=00m21s

[Sirocco20348]

Ok so i installed my new 710N DV. This improved the situation. So instead of the long drawn out chewbacca noise... its very quick.

TBH I cant be bothered spending $180 on a forge DV. Has anyone had any experience with the forge replicas selling for about $70?

VW GOLF MK4 PASSAT BORA BEETLE 1.8T DUMP BLOW OFF RECIRCULATING DIVERTER VALVE | eBay

[Lito]

Ok so i installed my new 710N DV. This improved the situation. So instead of the long drawn out chewbacca noise... its very quick.

TBH I cant be bothered spending $180 on a forge DV. Has anyone had any experience with the forge replicas selling for about $70?

VW GOLF MK4 PASSAT BORA BEETLE 1.8T DUMP BLOW OFF RECIRCULATING DIVERTER VALVE | eBay

im running the 007 knock-off works fine, sounds great, looks good. just doesn't have the forge logo on it, hasn't exploded my engine yet

[Sirocco20348]

PROBLEM OFFICIALLY SOLVED! Lito is indeed the man!

Solution: Installed the forge knockoff diverter valve.

VW Audi Diverter Dump Valve DV 1 8T 2 7T 007 NEW | eBay

End thread to this problem!