Strange Rattling Noise

[oaybar007]

So my car has been making a strange rattling noise lately and it's driving me nuts.

Under light acceleration and deceleration i hear a loud rattling from underneath the car that sounds like its coming from the transmission almost like something is lightly catching down there. It happens the most when decelerating in low gears and rpms (1st , 2nd & 3rd gear) but I have heard the noise decelerating in 5th and 6th at around 60mph.

The noise almost sounds likes the two rear bolts of the bellypan came out and those thin metal braces are banging up and down or a loose exhaust. I really hope that it's not syncros or any clutch/trans issues but I am at 73k so I wouldn't be surprised if it is.

Anyone have any ideas?

[Zoidbort]

You sure it isn't your brake pads rattling on your rotors? Mine are doing that right now and it sounds like metal on metal clacking around. Apply your brakes while driving and see if the noise continues, mine ceases when I apply the brakes.

[kwimberly]

Cat?

[mtshank]

I had the rattling sound from underneath my car for about a week until my fuel pump went out. I replaced the fuel pump and the went away Viola>>>>>>>

[old guy]

Put your car up on some ramps, get underneath with a rubber hammer and gently tap all the heat shielding between the exhaust and body of the car. Also checkout all the exhaust hangers. I am guessing you will find the problem somewhere in there.

[oaybar007]

I'm putting the car up on jackstands after work tomorrow to check it out. I'm going to take photos in case anyone else has a similar problem.

[KIDLALA]

I have this issue also so please let us know what you find...thanks

[diztek]

me too. mine is heard when i accelerate. ive noticed it in 1st 2nd & 3rd gear. in each gear it will occur as i give it some gas. its really quick, it only does it as i give it gas.

[kwimberly]

me too. mine is heard when i accelerate. ive noticed it in 1st 2nd & 3rd gear. in each gear it will occur as i give it some gas. its really quick, it only does it as i give it gas.

That's exactly what my old Jetta did when the cat went bad. It was the junk inside the cat rattling around - only did it accelerating into a new gear.

[diztek]

That's exactly what my old Jetta did when the cat went bad. It was the junk inside the cat rattling around - only did it accelerating into a new gear.

THANK YOU. no one has been able to even suggest what the problem may be. Ya, only in a new gear, although if, im in say, 3rd gear, ill hear it, then ill let of on the gas, coast a little til the rpms drop, give some gas and ill here it again. O man, you just made my day. I hope it is the CAT, that'll give me a reason the get a HFC.

[AudiA4Turbo22]

mine used to do this as well for me it was my tranny mounts! now when i hit bumps it rattles!

[kwimberly]

wow - I found my post from 2002:

http://forums.vwvortex.com/zerothread?id=310735

[Killerteve]

When I had that noise it was because two of the subframe bolts had come loose.

[oaybar007]

I haven't had time to get this freakin car up on jacks to investigate. I'm taking it to the dealer so they can check it out. Whatever it is I hope that my CPO warranty covers it.

I'll let everyone know what happens. BTW the noise has gotten worse and I hear the rattling whenever I'm below 40mph.

[BIG E]

i have something similar on my usp, it sounds like a belt squeaking almost, but i have a feeling its a heat shield or cat now.

[oaybar007]

Car is going to the dealer tonight. I will let everyone know what it is. The rattling has gotten worse and now happens in every gear under acceleration and deceleration. Even at 70mph when I let off the throttle i hear a snap, crackle and pop.

The car holds boost, runs fine etc etc. I bet that it's the cat. Wish me luck!

[diztek]

please do tell. dealer said my noise was not from cat. he said it would be hard to determine where the noise is coming from. he suggested i check the heat shield by the diverter valve. looking for a mystery noise can be a long process and i did not want to pay $100 an hour for someone to find it for me. ill have to play around underneath the car next time i can get it on my friends lift.

but please let us know what the dealer tells you. thx.

[oaybar007]

Ok so the car is still at the dealer but the noise has been diagnosed.

(Keep in mind that I had a really quick conversation with my service adviser so I don't have all of the info right now.)

The noise is the result of a broken exhaust hanger under the car probably caused by our many potholes in the Baltimore/DC area. What's happening is the pipe(s) are banging against the heat shields under acceleration and deceleration thus causing a clanking sound. The problem was not Cat related and the fix is going to be covered under my CPO warranty. I'm not sure if the hanger completely separated or if something just snapped but I will find out tomorrow.

Now here is another twist. I'm at 77K and was planning on having my TB service done next month. I know that I am pushing it but I figured that I could get away with it. Well today is the day that made me remember to go by the book.

After the tech road tested my car he discovered a substantial leak coming from my water pump. A sure fire sign of a complete failure not far off. My coolant indicator has gone off twice in two months but I didn't think much of it since it happened on days where the temp was around 95 but I should have known better.

So the good news is that my CPO warranty covers the pump and labor and the dealership is actually going to perform the TB service on it at the same time as the install saving me $$$$.

I'll let everyone exactly what happened with the exhaust when I pick the car up.

[old guy]

You must have missed my post in this thread last May.

[Carlitos]

You must have missed my post in this thread last May.

After reading this thread I thought of the exact same thing...

[oaybar007]

No no I saw it. I just couldn't find the time to get the car up on jacks to investigate myself. I'm a web designer and business has been good for me lately so all of my free time is consumed by work.

Old Guy you are the unofficial help desk king of the forums. Whenever I have a problem I search your username first and usually find the answer to my question right there. :)

[diztek]

thanks.

[golgo13]

wow - I found my post from 2002:

http://forums.vwvortex.com/zerothread?id=310735

I have this problem but I swapped my cat for a testpipe with down pipe and still have the same issue. Could this be the fuel filter it sounds like its gurgling gas?

[oaybar007]

Sorry for the lack of pics. The problem on my car was the connector between the two mufflers at the back of the car. Basically there was a piece welded to the ds muffler and another piece welded to the ps muffler. The two pieces were connected in the middle by a bolt with the ds muffler piece having the bolt going into it. Well the part of the piece that was welded to the ps muffler snapped and the clanking noise was the piece hitting the muffler.

I simply unbolted the piece and that solved my problem. If anyone wants pics I'll see if I can dig them up.