4x4 problem
 

I have 2006 150 extended cab xlt. In dash 4x4. I noticed quite bit of noise coming from the front passenger side axle. I replaced the IWE Solenoid and one check valve was bad. Which way do the check valves go? I know this is a dumb question but my dad helped me work on it and the way they are doesn't make sense to me. Is the black part that says vac go toward the engine? I don't see how any vacuum makes it to the solenoid like this. But the solenoid replacement did not help with the noise. It is now worse and will go away when I switch to 4 hi. What do I do next? I had also had the the vacuum lines checked and there is not a problem in the lines. It is the wheel ends?

Did you get a vacuum pump and check that the wheel ends hold vacuum? The reason turning on the 4x4 quites the noise is that the wheel ends are engaged and the transfer case is spinning. vacuum holds the wheel ends disengaged. I have the same problem with mine, and am trying to figure it out also

Yes, did all that. And the IWE Solenoid did fix it. Dummy me, I guess when I test drove it the first time after I installed all of the air wasn't out of the system or something. Messed with it some more and test drove, works fine, no noises. Thanks for the reply.

And you retested the 4x4, jacked one front wheel up, and while engine is running, spun the wheel that is off the ground and made sure that its not engaged (front drive shaft not spinning)? 4x4 hubs that have no vacuum to them are hard to notice, until you fill up the tank next time.