Hey everyone, haven't been here in a while - lots of new names... anyway,

My car recently started making a noise that I think is probably the catalytic converter going. When I rev it there is a rattling noise, which is loudest after I let off the gas and the revs start to fall. If I knock on the catalytic converter should I be able to hear rattle if that is indeed where the noise is coming from?

And if I buy a CC off the web, what would be a fair price to get it welded in (and the old one taken out)?

Thanks all

 

what kinda car you talking about?

 

Sounds EXACTLY like what happened to my car; (1.8T)
turned out to be a wastegate failure. unfortunatley, you can't just get this part on it's own.
Now I gotta get a new turbo. [:@] (anyone got one they wanna sell?)

Dunno what what engine U got, but I hope this info helps.

 

1. You can buy wastegate separately from the turbo.

2. The rattle might be either the converter or a heat or stone shield. Check under the car.

 

I have a 99 A4 18.T FWD.

It has 118k on it, got it chipped at ~113k.

The turbo and head were rebuit at ~80k when the timing belt broke (I didn't own it at this time!)

In other news i got a quote today for a few (i thought) minor dents from a recent accident (merged into same lane as someone else on the freeeway) -- $1600....ouch, but I'll be reporting it to insurance....


So david (or anyone), when you say check under the car, what exactly am I checking for?

Thanks

 

Does this happen when the AC is on? I'd look at the Wastegate, Cat and the AC.. those are likely the primary culprits.

 

1. The wastegate in these cars (and most road registered cars) is an internal type. This means it is incorporated into
the exhaust side of the turbocharger. The wastegate is a metal flap, the noise in my car is the loose flap bouncing and vibrating when
i'm off the throttle.
You would have to purchase and replace the whole exhaust side of the turbocharger to fix this problem.
My problem is that I can't find this part just on it's own. I'm in Australia and Audi parts a expensive and hard to find.

 

OK, so I've been driving like this for a while now.... I was getting my oil changed so I went down under the car and had a guy rev it for me. The sound seemed to be coming from the engine (top?). It definetly wasn't the Cat. Maybe the waste gate.

......on to today:

I was going up a hill, pretty fast, pretty high revs when I heard a noise. Now my car sounds like it has a different exhaust or no muffler or something. Very different sounding, but kinda sounds "cool" if you know what i mean. The rattling is gone. No noticeable power loss.

So did the waste gate break or something? Should I be worried about driving it like this? I'm going to drop it off thrusday morning for body work (got in a little accdient). Should I get it looked at by a shop tomorrow? I don't want to do any (more) damage.

Thanks

 

If the wastegate was flapping or if it was broke and not closing, you would have very poor power. If the wastegate is open you can not build boost pressure because the exhasut gas goes out of the wastegate and therefore does not turn the turbine side of the turbo. This means that the compressor side is not turning and therefore, not making any boost.

If your car is performing normally, your wastegate is fine. If your car is performing normally, the internals of the catalytic converter are fine. What happens on alot of cats is that the welds holding the heat shield on break and then the heat shield rattles.

I would definitely take it to a shop or get a friend to help. Rattles are too hard on your own.

 

looked under the hood tonight and found the culprit. An O2 sensor popped out of it socket in the exhaust. Tried to get it back in, but i think the threadas are screwed up. Is it bad to drive like this. I have no CEL. And any suggestions to getting it back in there? Hopefully the threads are only screwed up on the sensor.