This question actually applies to my girlfriend's '98 passat 1.8T, but i figure the engine (and turbo) are probably similar enough that the basics still apply. When accelerating in her car, up through the 1500-2000RPM range, you can hear a noticeable whirring sound from the engine compartment. This is most noticeable when you feel the power kicking in (i.e. turbo boost). I am confident this is related to the turbo, does this mean the turbo is in its death throes, are not that bad? Something that could be fixed, perhaps? When she bought the car (used) the turbo wasn't working at all - some piece had been stuck (copper-colored piece, looks like a little drum with a rod sticking out of the middle of it). This was replaced, causing the turbo to operate again.

Anyway, i'm trying to figure out if her turbo needs to be replaced, and if so, maybe I could put a KO4 in there? That'd be pretty sweet. There are no other symptoms, except one, that occurred 1 time: last week, while punching it on the highway (i don't speed, this was an evasive maneuver) the turbo spooled up, and then just sort of stopped - i heard a woosh of air and i had no power until I let off the gas and tried it again. Only did that once, and since then no problems except the whirring. Thoughts?

BTW, the whir sounds like a light steam-engine whistle, but higher pitched.

 

i'd go with those first.

get a forge DV and check all the hoses for cracks. worst case spend $150 on a used k03 and the rest on install/chip and be happy again.

 

DV = diverter valve, correct? My car's a 3.0, so I don't have much experience with turbos... Where could I get a forge DV?

 

you do her timing belt yet yes?<ul><li><a href="http://www.ecstuning.com/stage/edpd/pagebuild_v2.cgi?searchstring=diverter&amp;searchq t=byvehicle&amp;make=Audi&amp;model=B5+A4&amp;subm odel=Quattro&amp;engine=1.8T">go here and look around.</a></li></ul>

 

But I'm not positive, i'll have to check on that. Is the diverter valve something I could do myself pretty easily, or does it involve a lot of work?

 

timing belt kit is done every 60K miles, fuel filter, brake fluid flush, tiptronic trans fluid flush, all that jazz should be done on regular interval.

It's just a really f'ing tight fit trying to finagle the DV with those VAG pinch hose clamps.
Depends on your motor skills though.

I usually queue up a list of things to do then send the car on to the local mechanic. spending 8 hours dickin around where as i could pay for 2.5hrs at the mechanic ($50/hr). My time off is better well spent relaxing lol.

 

I can get a new OEM diverter valve and replace it, but do you really think that's what's causing the whistle sound?

 

could be numerous things. "whistle" can sound like a blown turbo too. thank god used ones are a dime a dozen lol.

but still stock DV is prob wasted and leaking , along with vac lines/boost tubes if you didn't keep up with the maintenance.

 

As far as the leak
it could be a vacuum line
a torn hose
DV
N75
Wastegate
Turbo
ECU

The best thing to do is get the car logged by a performance shop to find out what is going on with the car and go from there, before you start replacing parts left and right.

 

does that help? I experienced a large drop in power.
Typically a bad stock diverter valve sounds like blowing over the top of a soda bottle...but little power loss...with rough performance.

Just as Mrkrad said, start with the small and easy stuff. But having a dealer diagnose will cost you around $100. That may be the way to go and they should be able to tell most of all the boost/vacuum associated problems...might be worth it.