Lift throttle rattle?

[jws]

I am getting a subtle rattling noise when I lift the throttle, generally between spirited shifts, i.e. in the boost. I suspect it has something to do with the turbo system. I don't think it does it with gentle driving.
jws

[b5a4erik]

Could be a loose wastegate.

If it's loose it might rattle on decel.

[jws]

Forgive my ignorance, but is the waste gate on a K03 part and parcel of the turbo? If so, could this be interpreted as a "death rattle"
Or is it part of the down stream plumbing and easily replaceable?
It as an APR stage 1 chip, would my performance be compromised by a loose waste gate? What symptoms should I be looking for?

Thanks,
jws

[TheRedGlacier]

I too would like to know, my B5 just passed 200k a few weeks ago, and I've had a 200k rattle on deccel. Most noticeable around 2600-2800. I don't know if it is a loose wastegate or what. I've heard loose bolts on the cat to downpipe, or a cracked exhaust gasket will make this noise. It seems to be loudest on the ground next to the DP and cat. But I still figured I should look into the possibilty of a loose wastegate.

[b5a4erik]

Yo peaps,

The wastegate is part of the turbo. There is a rod on the outside of the turbo, the wastegate actuator rod, that is positioned behind the exhaust manifold. That rod connects to the internal part, the wastegate itself. The wastegate is basically a pancake shaped valve that either opens, or closes & covers a hole to either build boost or depower it.

I'm sorry to give you this news, but there's only a couple of options that I know about here:

1. Wastegate actuator rod could just need adjustment, to tighten it so the wastegate sits better on the hole it needs to cover. (if it's loose, it'll rattle a bit)
2. The wastegate might be completely blown to shreds with it's fragments in the catalytic converter. In this case, You'll likely need to buy a new turbo. (if it's blown, it'll rattle a good bit "death rattle?")

Either way, you'll probably need to - easier yet still difficult then it sounds - pull the turbo, or atleast remove the cat to have, to paraphrase someone who recommended it to me, a "look-see."

For a loose wastegate, perhaps uneven boost.
For a blown wastegate, you'll probably barely boost at all.

[TheRedGlacier]

Alright! Very informative. I think personally my B5 might be dealing with something at the base of the exhaust, or perhaps a heatshield, it sounds like a non metallic rattle /noise, more like aluminum or plastic. But my boost pressure is consistently 15 - 18 on WOT

[PsorianoPre99A4]

Mine did the same rattle noise on decel When I took the turbo out the wastegate flapper inside the turbo was loose (broken). I had only about 1 psi lost of boost on my stock AEB I was about 6 psi. I was told it may not be necessary to replace. But if you don't like the sound and plan on adding power, i'd change it.

[b5a4erik]

Alright! Very informative. I think personally my B5 might be dealing with something at the base of the exhaust, or perhaps a heatshield, it sounds like a non metallic rattle /noise, more like aluminum or plastic. But my boost pressure is consistently 15 - 18 on WOT

That could be as well.

I had a loose bolt simply for holding a bracket on for the longest time... rattled only @ certain RPM's and drove me crazy. I took it to 2 shops until I finally just decided to check it out for myself... tighened it for like 1 minute of work and problem solved. The things you find when you take a good look @ your car...