Too much noise in my Passat??

[shaggygti]

Hi there.

I have a 1995 AAZ engined diesel passat. I’ve been told by a friend of mine that these passats had a mod done on recall where-by a flexi-hose was added into the exhaust system in the horizontal section just after the down pipe.

This was done to reduce the resonance into the cabin from the engine. I know my engine will never be the quietest however Id like to reduce the cabin resonance.

Is anyone familiar with this mod??

Thanks, Shaggy

[erico]

Nope. I just took a look at my Bentley subscription Online and perused the Recall campaigns. There are no recalls listed under exhaust for 1995-1997 model Passats. As far as I know, Bentley keeps the list up to date. If you are hearing a buzzing sound...you might want to replace the rubber exhaust hangers. They arenot expensive and quite easy to replace. When they are near failure --> noise is the result. I replaced mine and the noise went away. This issue was adressed in another thread a while back.

cheers,
Eric

[JohnSt]

Hi,
I two seek the quiet exhaust for the early tdi passat!!
I would dearley love to know where the extra flexible section was welded in! May be it was not a VW mod?
I have just changed my exhaust hangers sadley with little effect.
see below.
If you crack it please let me know.

Erico Hi,
The good news! We had a dry spell in Wilts that allowed me to change the exhust hangers!!
The bad news!! I still have the harmonic vibratiion at 1200 & 2400 rpm.
While grovelling beneath the beast, I also checked the front down pipe flexy section was nice and free and flexible which it was so i'm back to square one.
I have managed to moderate the vibration by a heath robinson arrangement giving some sideways pull on the back box,(pulling the twin pipes at the end of the system to the near side) which is not the most eligant solution but has given me about a 60% reduction in the vibration.

[erico]

Hi JohnSt,
Sorry to hear that. Well, it is a good thing that exhaust rubber hangers are cheap. That was worth a shot.

How sure are you that the vibration is coming from the exhaust itself? The source could be on the motor itself and perhaps caused by a worn serpentine belt or free-wheeling clutch pulley on the alternator. Does the engine run smoothly? You might ask a mate to sit inside your Passat with the engine running and gently up the throttle to the RPM range that you mentioned. You might very well hear and see the cause. Are your motor mounts in pretty good shape? Do you have access to a VAG-COM and laptop? You can plug the VAG-COM in and go for a test drive. Then you will see just how well (or how poorly) your engine is performing. Engine management faults can mislead one to think faults are elsewere on a vehicle.

Please keep us advised on your progress.

cheers,
erico

[molgrips]

I have the same problem - exhaust resonance clearly audible coming from the back of the car when driving at over 2krpm. I'm sure it's caused by the water pump drive belt vibrating, since when I watch it flap about it seems to mimic the way the noise behaves at different rpms. I've changed the water pump, and I've removed the power steering belt all of which helped quieten the noise, but it's still there.

The pulleys themselves didn't appear to be on properly, they were wobbling a bit, but I've carefully replaced them and again it helped, but didn't cure it. Don't know how to stop that flat belt flapping about.

[molgrips]

Oh, a question - how do you check if the motor mounts are ok?

[caldirun]

I have the same problem - exhaust resonance clearly audible coming from the back of the car when driving at over 2krpm. I'm sure it's caused by the water pump drive belt vibrating, since when I watch it flap about it seems to mimic the way the noise behaves at different rpms. I've changed the water pump, and I've removed the power steering belt all of which helped quieten the noise, but it's still there.

The pulleys themselves didn't appear to be on properly, they were wobbling a bit, but I've carefully replaced them and again it helped, but didn't cure it. Don't know how to stop that flat belt flapping about.
Does the waterpump belt drive the alternator on this engine, if so change you alternator, its the pulley clutch siezed

[molgrips]

The alternator is on the same belt, yes. But its pulley really looks like a one-piece on my AAZ engine. Apparently I can get a pulley with a clutch from the TDI engine and retro-fit it, which I will do.