MKiii making a weird noise
 

My mkiii turbo auto. that i just bought which is num 3 for me has been makin a weird noise sounds like out of the transmission. the tranny has been rebuilt in 08 car came with the receipts for rebuild. its kind of a whining noise and it gets louder with rpm's i am planning on doin a auto to manual swap but i dont have the money for that right now. car kinda feels slow motor runs good beside the knock sensor code (in the middle of rewiring them) not surre if tranny is to blame but comin off freewy decelarating rpms jump up and down?? any suggestions would be greatly appreciated. Thanks

So i am starting to think my cat is clogged the noise goes away when its warm. and yes it has completely stock exhaust no bolt has ever been un turned on this car..

Is it common for cats to clog on these cars although i know not many of them have them anymore and mine is only goin to have one and turbo back exhaust ASAP. does anyone have one for sale.

Car feels alot more responsive since i rewired knock sensors but turbo lag is just crazy.. I have taken intake off and checked turbo and wastegate both are in good workin order no bearing play.

They generally breathe well enough to avoid clogging... that's not to say it doesn't happen.... too much carbon released all at once thanks to the brilliant use of seafoam or similiar... too much soot from run deadly rich... collapsing of the catalyst structure due to significant vibration or a couple bad hits to the front of the unit.

How quickly is the turbo spooling? What kind of mileage are you getting? Have you checked for exhaust leaks?

the guy i bought it from did mention something about sea foam.. i took the car today to get it inspected and emissioned and it passed with flying colors so i dont think its the cats anymore...

the noise goes up with rpm so maybe like the main shaft bearing in the tranny i am thinkin..

and for the turbo lag i took the BOV out to atmesphere and blocked intake hole (just for troubleshooting) and it starts whistling while im in boost so the BOV is not closing all the way im sure thats my problem there..

have yo heard of the shaft bearing going out on rebuilt tranny? the car has 176k on it so there is a chance they didnt change the bearing during rebuild.

A clogged cat doesn't mean you'll fail emissions... a glazed cat means that. The stock cat flows maybe half the capacity of the engine at a medium load... actually, probably less.

Could definitely be the bearing, never presume a component (even new) isn't likely to fail. I was under the impression that when those bearings went that you felt it more than heard it though.

Very much not a fan of seafoam... but in this case even steaming the inside of the engine could have the same effect of loosening too much debris at once.

Did some more wrenching today and set the timing with the jumper in at 10 degrees it was at 15 and now the turbo spools noticeably quicker...this is the fun part about buying a car u get to go CSI to find there mistakes... car runnin better everyday so I think injector were dirty . Ordered a new saab bpv to fix boost prob. but the noise is bugging it goes away when warm and whn in gear stopped. Definatly coming from the pass. Side. I appreciate all you help. I'm stumped

One thing to remember with timing.... The greater the advance the longer the fuel is burning before the valve open back up... this means there is more heat (energy) absorbed by the block which the oil and coolant have to displace and less energy in the exhaust charge... it's denser and slower and in the worst cases the engine actually has to push to evacuate it and it can't get it all out before the intake valves open.

Just a quick thought, if the cat is partially blocked it could possibly produce a similar whining/wheezing noise around the gearbox area of the car. Decat pipe ftw ;) (and keep the cat for test time) before throwing money at tranny etc.

Oh, and it's definitely not a wheel bearing is it? Don't really think temperature would affect that but another relatively cheap thing to check out...

No definatly not wheel bearing it does it at idle in park. I'm gonna pull the cats off I just bought a 3" downpipe but won't be able to put it on for 2 weeks when I get back from vacation. I'm still leaning towards the cats bein clogged up and hopefully this will fix it. Ill post when I get some more info. Thanks for the help.

Ah, so we have the noise sat still in park... right then... what about sat in neutral? (I know it's silent in gear as I saw that bit! :))

It is sounding more like gearbox/torque con. now you mentioned it being noisy in park. I hate trying to diagnose noises remotely, really need to be at the car & have a play round to find it!