2004 Audi a4 3.0 quattro need to know where the thermostat is..and how to replace it..also wastes gas..a lot..my son bought it from a private party

This is where the thermostat housing is,front side,between the heads,

Follow the top hose on the radiator to the t-stat housing.

Thank you ..but is other a video that y'all may have..shows step by step...to get started? Thanks.

Woah! hold your horses caballera- you got in deep just buying this complicated piece of Teutonic Trouble- don't make things worse by messing around under the hood when you don't know what you're doin'- the best course is to get rid of it, fast- but if you insist on keeping it, find a GOOD Audi mechanic- oh, please, just get rid of it-

lol jam. Audis are not so bad once you got a good mechanic. I do all the work on mine myself unless it requires a hoist. So what you need to know... Replacing the thermostat is a big job, it is often done during a timing belt change along side the water pump, pulleys and tenser. This at audi is a 1500$ job but at a skilled audi/vw specialist some where more in the ball park of 1000$. if you only just bought the car and have no idea how long ago the timing belt was changed i would recommend going back to the person you bought it from and ask. If they do not know just do the whole kit to save headache down the road. i would also have all the pvc checked for the crank case breathers. more often then not one of the pvc tubes disintigarates on the 3.0L engines and causes the car to stop running or idle badly.

https://www.youtube.com/watch?v=ppxIcWZtE7w and this video has the termo stat in it or at least it should

Pelican parts have a good guide on how to do this job with photos if your handy around cars. might help??