pull it off and do a blow test. it should plug up one way and flow the other way. when i swapped mine out the one on the side of the manifold wasn't working. as long as your vac lines are in good condition then changing out the one on the side of the manifold should fix it.

you can see it directly above the 4th rocker arm from the left in this pic.

 

That check valve is good. However, the one going into the firewall is bad.
I just went to all the auto parts stores in town (NAPA, CarQuest, and Federated) and none of them have a check valve that will fit... Where do I find a replacement?

 

It may be a dealer specific part, maybe a junkyard, LMC truck, other online outlets, or worse case scenario, get a universal one.

 

dealer is the only place you'll find one to fit locally. you could get a universal and find some rubber hose to make it work. i just went to the dealer and got 4 of them a while back because mine and my dads trucks both needed them replaced. after i replaced mine it didn't help so i know i have a vac leak somewhere but it did fix my dads truck.

 

dealer part...they're about 8 dollars per.

 

8? mine were like 3 and change at the dealer.

 

Oh, ok thanks. I'll try the dealer tomorrow. Not sure they'll have it. Kind of a small place with Dodge trucks and Ford..

 

Every things always more expensive here in California.

 

well it turns out that i don't have a vac leak. i changed my pcv valve a couple days ago and now my vents work like they should.
i also put the cai back on but i think it was the pcv valve that did it.

 

Thanks to this on the forum.

I have known what the problem with my wild and crazy vents and cruise since I joined up here. The later functioned but was always underpowered (lost speed) uphill.

Today its fixed and for only the cost of gas to go by the auto grave yard. Used the blow test and had a couple in a matter of minutes. "No charge for that stuff." Was the young lady at the counters reply. She can do that she owns the place. She's not bad looking and who doesn't like the smell of oil and gasoline, but somebody beat me to the parts. I mean her!

Good job and a special thanks again to all that contribute. It makes life easier for all of us owners that won't just put our "still"good trucks down.

Over 200k and counting thanks in part to Dodge Forum,

JJ