05fx4. I have been having problems with 4wd Vaccum system I believe. My 4wd seems to engage fine but while driving in the higher rpms I get a wierd rattle from the front end. It's been getting worse. After researching I decided to look into the Vaccum system. Now if I was betting man I Woukd have easily bet that the noise rattle was coming from my passenger side. Simply because while driving with windows down in driver seat it sounded that way. Today I hooked up the Vaccum pump to the iwe on the passenger side down by the hub. I removed the double hose attached to it. Hooked my hand pump up to it. I pumped it up to 25lbs and it seemed to hold the pressure. I attempted the same thing with the driver side and I couldn't Even get it to hold any pressure? So I am guessing that's my problem. But could that side not holding pressure or Vaccum cause the other side to rattle? Or was I just going crazy thinkin it came from that side. Also is that possible for my hand pump to not be able to get it to hold any pressure at all?

 

If vacuum is lost on one side, both will be affected. They both will try to engage.

 

Sounds like the internal seal on the driver side IWE is bad. If the passenger side vacuum line, the solenoid or a check valve is bad the other side will malfunction too. Sounds like you're where I was three years ago.

Trouble shooting;

http://www.ford-trucks.com/forums/83...then-some.html

IWE replacement, including tools needed;

https://www.f150online.com/forums/20...replacing.html

It's not too difficult to do in the driveway, and you'll save hundreds of $$ in labor.

 

Yes

http://www.f150forum.com/f72/how-dia...m-esof-186872/