Hi all,

I have a 2001 2.7t manual with 95k miles. A few weeks ago I noticed that the car was making a loud fan-blowing type noise when it got hot, but didn't seem to have any other symptoms. I brought it to an independent audi shop, and the owner said it sounded like it was the mechanical fan to him. Now that it is getting warmer, the fan is coming on more often, but I've noticed that the car is also extremely sluggish when the fan is on. I can hear the turbos spool, but the car doesn't feel like it is getting any boost. It almost feels like something is holding the car back.

I realize that it's probably not the fan directly causing the sluggishness, but the symptoms seem to come and go together.

There's no check engine light and the fan/sluggishness come and go, even when the car is hot.

Any thoughts?

Brian

 

As air gets hotter, it expands, so when the air is very hot and it entered the engine, the fuel to air ratio is much less at higher temps because it is expanded than it is at colder temps. Now I have noticed a difference in pickup during cold weather than in hot but not a huge difference, if your noticing a very big difference I'm not sure but you should know it is normal for the car to not create as much pickup in warmer weather than in cold weather.

 

It's definitely much more sluggish than normal. Additionally, the symptom comes and goes from minute to minute, even at the same engine temp and same outside temp.

 

Sounds like a boost leak. The hoses get hot and expand opening a crack somewhere in the system.

 

Are there any places where a boost leak is more likely to occur?

Is it possible that the diverter valve is malfunctioning at high temps?

 

Its possible, but theres a good chance that if they are malfunctioning they just need to be replaced. Common places for hoses to tear are throttle body boot, intercooler inlet, and turbo inlet.