Audi a4 1.8T - sounds like a dump valve!

dodzy

Hi all, have a 2002 A4 1.8t quattro with 120K on the clock. When at the point of changing gear ( as you come fully off the throttle ) there is a whistle sound ( or maybe a "pshhhhhhhhh" would be a better description !) . Sounds like a dump valve on a boy racers car.

No other noise from the turbo under normal driving / acceleration. Has a passat prior to this with a similar config and i changed the turbo at about 100k as a result of a constant whining under all driving conditions. The impeller was in bits in that situation, but i think that this issue is different. Any ideas??

mathepac

Sounds like one of the clips connecting the rigid and flexible inter-cooler hoses is working loose or an inter-cooler hose is about to split, they may decay or stretch over time.

If you are handy with a screw-driver / spanner and are a contortionist you can fix either problem easily

dodzy

mathepac wrote: »

Sounds like one of the clips connecting the rigid and flexible inter-cooler hoses is working loose or an inter-cooler hose is about to split, they may decay or stretch over time.

If you are handy with a screw-driver / spanner and are a contortionist you can fix either problem easily

Good man, ill get out the trolley and the axle stands. Lovely day here in dublin ! Dont suppose youd know where id pick up a used under-engine cover ( the large plastic section which gives some protection to the sump )? lost a while back! Tried summerhill / kilcock dismantlers regularly.

mathepac

Sorry, other than the generic "try the nearest scrapyard" response I can't help with the undertray.

I hope it doesn't spoil your day if you do a load of work and it turns out my diagnosis is wrong.

Lovely day here too TG.

p.s. If I remember correctly the intercooler is mounted behind the RH side wheel-arch liner. If you loosen a few torx screws it may give you access; taking the wheel off depending on rim/tyre size may save the back a few twists.

Nissan doctor

If there was an intercooler pipe lose you wouldn't be able to build boost so you'd be down on power and there would be no back pressure to create the noise your hearing.

Have you got the car long? All turbo cars make this noise when you lift off the throttle. If yours is very loud then a loose pipe between the airbox and turbo or the airbox itself not sealed properly are the likely culprits.

Neilw

Nissan doctor wrote: »

Have you got the car long? All turbo cars make this noise when you lift off the throttle. If yours is very loud then a loose pipe between the airbox and turbo or the airbox itself not sealed properly are the likely culprits.

Vag 1.8t`s hardly make any sound when you lift off. I had the same sound the op described and it was the small vacuum hose which had come off the top of the diverter valve. Can't remember the fault code it logged but a scan with vcds said to check dv.

dodzy

Neilw wrote: »

Vag 1.8t`s hardly make any sound when you lift off. I had the same sound the op described and it was the small vacuum hose which had come off the top of the diverter valve. Can't remember the fault code it logged but a scan with vcds said to check dv.

Yeah Neil, agree that the VAG I have ( passat was same ) - virtually no noise on throttle release before the issue. The only noticeable sound from cabin was on a quiet day, window down, under hard acceleration ( that lovely whizzzzzz :-))

I'll check the DV when the rain stops. Nothing noticeable though from my inspection last week :mad:

Tea drinker

The DV are easy and cheap to replace if yu wanted to go that way. Like Neil said, check the actuation pipe running to the DV.