I had a VERY hard time (in fact, I missed it twice) locating the leak in the "hard" section of my vacuum line. It is a dark spot, with dark colored lines. Try using a section of rubber hose (as suggested) and/or utilizing a vacuum gun if you have not already I was finally able to hear the leak hissing and found it that way.

 

Last night I removed and plugged the left side (driver's side) IWE vacuum line and when i did the vacuum on the right side IWE vacuum went from 5" of vacuum up to 17" Does this indicate that possibly the left side IWE is the problem? When I reconnect the left (driver's side) side vacuum hose the vacuum drops back to 5" on the right IWE vacuum hose. CRAZY!

 

When you say left, I am assuming you mean driver's side? From your findings there, I would think that the leak is in the IWE on that side, and not your line. Pull a vacuum on the IWE itself with a vacuum gun and do a "leak down" test maybe? Hope this helps!

 

When you have a vacuum leak like that IWE could stand for "Intermittent Wheel Engagement". I'm hoping my short, weird, and very intermittent sound is related to a loose exhaust hanger or bad muffler baffle. (while accelerating and turning left at times it howls from the rear... you hear it but you don't really "feel" it) 2004.5 F150 5.4 FX4.

 

Good day! I have a 2005 F150 XL 4wd maual shift and since the winter I have had an issue shifting out of 4wd into 2wd. The light on the dash goes off, then after a couple of seconds I get a loud bang. Took it to a mechanic and he said it was the transfer case so I ordered a used one off ebay had it installed and still same issue. He next stated it was the solenoid and actuators. Put them on and still same issue. I next found this post and discovered my first check valve was bad between intake and second, replaced that same issue. I next discoverd that my vacuum box was bad where I had previously blew out the lines, replaced that same issue. I have perfromed all of vacuum test listed in this posted, and do not believe I have a vacuum leak. Only thing I havent done is replaced the lines. I can shift it into 4wd drive, drive, stop disengage it back up and it doesn't do it; however, if I disengage it stopped and go forward or at a low forward speed i hear a terrible bang. It sometimes also does it when engaging. Any help would be appreciated, I am at my wits end.

 

sure sounds like you have an IWE hanging up; have you pulled one/them off to inspect?

i'd look into a different mechanic too..

 

I just put the new ones on there two weeks ago. The old ones looked fine.

 

ah, gotcha, didn't see it listed in your first post. that's certainly strange.

 

yea it is really frustrating...i took the lines off going to actuators and supplied vacuum and they checked out. I have no idea what it is..only thing is not new is the vacuum lines....and i did not see a drop when I tested those lines

 

It almost seems like you are getting vacuum, but not enough to completely D/E the actuators? If there are no leaks, what kind of vacuum are you getting @ the IWE?

 

Thankyou for the great info. My truck would pop into 4wd at freeway speed and if I didn't get it stopped in time I make a very loud and disturbing bang when it comes out. I think the increase in vacuum when I let off the throttle causes it to come back out. I disconnected the vacuum line and plugged it like you said and that works but I am curios why the transfer case is not engaged because it sure was engaged when it pops into 4wd going down the freeway. Also I can't get the thing to go into 4wd low range. I haven't looked into that yet but wondered if you had any thoughts or anyone else. Thanks again.

 

Thankyou for the great info. My truck would pop into 4wd at freeway speed and if I didn't get it stopped in time I make a very loud and disturbing bang when it comes out. I think the increase in vacuum when I let off the throttle causes it to come back out. I disconnected the vacuum line and plugged it like you said and that works but I am curios why the transfer case is not engaged because it sure was engaged when it pops into 4wd going down the freeway. Also I can't get the thing to go into 4wd low range. I haven't looked into that yet but wondered if you had any thoughts or anyone else. Thanks again.

 

Woops. I am new to this forum and I thought that I had replied to the wrong thread. Thats why I copied and pasted it again.
I got a vacuum tester and the only leak I found was the vent line that comes back up to the solenoid. I'm not sure but I don't think that should be leaking. Maybe it means that one of the actuators may be leaking.

 

Nice writeup!!!
Just replaced RH wheel hub assembly with a MOOG unit.
Putting it back together I noticed that the actuator body was broken away from the attachment bolts with a hole at the top exposing the inards to all kinds of contamintion. problably resulting in the wheel hub failure?
Checked the passenger side, same thing!!! Mounts broken away from the body.
Not sure when this all happened. I could engage, disengage 4 wheel/2 wheel drive with out operational problems. never heard any grinding or whining except when wheel hub was going out.
What could cause this failure to both sides???
Havent checked vacuum yet or to see what happens at startup.
As I say, just noticed this and have been surfing for cause and parts.
Thanks

 

Awesome write up, thank you.