Whats the PCV valve do and does it need changed on a regular basis? If so when do you change it?

 

PCV is Positive Crankcase Ventilation and it is a plastic valve that draws air from inside the crankcase to prevent a build up of pressure so your seals do not over pressurize and leak.

How often to change it? Depends on age and mileage but if you have an 03 and havent done it yet then you should swap it out to be safe. When you pull it out it should rattle when you shake it. If not then it is clogged.

 

I've cleaned mine three or four times, but I did just recently replace it at 110K. They're kinda pricey, so you might want to try cleaning it. If the check valve moves, it should still be OK.

 

Where is it located? Does anyone have any pics?

 

You can download the '03 Service Manual from weed's sig. PCV starts in section 25-18. On the 5.7L it's located behind your throttle body on top of the intake manifold. Shows removal and installation in section 25-22. I just ordered a new one, still OEM on mine. Cost $19 on rockauto.com