Hello, I have experienced this wild vents issue for almost 2 years now. Thanks to this forum I have finally stumbled upon a place to look and others having the problem. On Friday I went to the dealer and purchased 2 check valves one for the line coming off the manifold...the other for the T going to the firewall. I still have the problem. What should be my next step...checking the vacuum canister located under the cowl or chasing down the lines?

Thanks for the help!

 

possibly a vacuum leak or the pcv valve. mine started working right after changing the pcv valve.

 

sheriff420..stupid question...where is the pcv valve located? do you have a part number on it?

 

It's located on top of the valve cover connected to the hose that goes directly to the side of the intake manifold.

 

any parts store will have the part number and its only about 5$. if you're going to change it (you're supposed to every now and then anyway) then do it with the engine hot. the rubber grommet that it is pushed into will be pretty stiff on a 10 year old truck.

FYI, the valve cover with the hose that goes to your air box is not the pcv, that is the crank case vent so don't mess with that one, the pcv will be on the other valve cover.

 

Great information zman and sheriff! Sheriff thanks for the further description...I was working on it earlier after my post and initially thought the valve cover with the hose to the air box was the pcv valve....until I looked closer it didnt look like the picture on advance auto's part list. The description you provided will make it alot easier for me to locate...THANK YOU! I hope that part is the issue otherwise it will be back to the drawing board.

on a side not...I pulled the vacuum reservoir tonight and checked it..it is fine so I hope it is the pcv valve..if not it has to be a hose!

 

If your truck has cruise control, there is a hose and cc module under the battery tray you might want to look at. And if it's a 4x4, does it work? Could be a broken line going to the shift motor on the front axle. I'm done guessing until you fill in your profile or sig with ALL the info about the truck.

 

hey zman, thanks for the additional info. I replaced the pcv valve today and still nothing. I will check the hose and cc module under the battery to see if that is the culprit. besides visual verification do you have any tricks in checking hoses? Yes it is a 4x4 and i havent checked it yet...I will engage it tomorrow and see what happens.

Thanks again for all your assistance!

 

if it is the hose under the battery tray then you will see that it is eaten up from battery acid. it could also be a damaged cruise control servo (the hose plugs into it).
if you can't see anything wrong with it or the line then you could plug off that vac line where it splits off on the passenger side of the intake manifold and go for a drive. that would rule out that vacuum line if it still does the vent switching.

look at post #31. in that picture look directly above the third rocker arm from the left and you will see where the vac line splits off and goes out to the right. that line goes to the servo and right where it splits off is where you should plug it with a rubber cap to see if it is that line or the servo causing the vent switching.

 

Hey Sheriff....I didnt have anytime to work on the issue this weekend but I will give it a shot this week. I really appreciate the help!!

Thank you!