New to me 2004 1.8T Quattro wagon, 50K miles, I have no service records (lease return vehicle). Seems to run well but when I first start it up it makes a rattling noise. Looking under the hood, I can see the accessory belt tensionser rocking back and forth. Almost looks like the tensioner wheel is not running concentrically but it's hard to tell.

It may just be the engine is running a little rough when cold causing the tensioner to dance and maybe the tensioner is dancing when cold making it seem like the engine is running rough.

Anybody else have a similar problem?

TIA.

 

Same year same engine, 75K for me. A metallic rattling, even when warmed up. tensioner is dancing too. Same mileage on my Passat 1.8T and the tensioner is smooth as glass. I'll be replacing the tensioner when I do my timing belt next month.

 

Now that I have a few tanks of gas through it, mine is fine. I think when the engine is running a little rough, the tensioner dances. I think my car may have had some bad gas in it when I got it.

Unfortunately I do have a CEL on with a P0411. Does anyone know how long the emissions warranty is on these cars?

 

Check on other threads but I do believe this is a vacuum leak...