6BUBBA9

2006 4.6 XLT 4x4. So i've read alot of the posts about the 4wd's on these things and cant seem to find anyone with the same problem. So ill tell you what ive done.The dreaded "grinding" noise started coming from the front end, so i came on here and read alot of people replacing the vacuum actuator, did it, sound went away, for awhile. It came back, so i took it upon myself to replace the 4WD vacuum lines, still making the noise. I taped off one of the vent lines off that vacuum line assembly and BOOM the sound is gone. So now that theyre calling for snow here in VA i went to make sure my 4wd was working, NOPE. Pulled that tape off, still not working. So I replaced the vacuum reservoir thinking that was clogged, still no 4wd. I can hear the 4WD "click" when turning the selector from 2H to 4H. It just will not engage. The grinding sound comes in at about 45/50 mph will in 2H, i put it in 4H and its gone? Someone please help before im forced to sell this truck. Maybe im just over looking something. I guess the next step would be 4WD hub actuators/and other front end extremities. HELP! thanks!

Rossco

The IWE. the vacuum actuators at the hubs.

Apply vacuum and the hubs release. Ok. You know all that.

Problem could be the check valve the separates the 4x4 vacuum from the rest of the system.

If you need 4x4 then just pull the lines until the snow goes.

If you have a garage then jack the front end up and spin the wheels to see if one is hanging up, aquire a vacuum pump / gauge and start at the L/H/F wheel.

6BUBBA9

this check valve, is that the one on the firewall?

where would you pull the lines? wheel side or upper side?

Rossco

2006 eh?

I have an 04 & 08 I will go take a look in a wh'ile and check back. (Unless someone else nails it on the head)

Funny tale, I aquired a pair of used IWE's from a 2011 EB because of the exact same problem, turned out to be that check.

When I was trouble shooting I would pull the IWE vac line and check for vacuum there, spit on your finger and hold it over the hose. It don't take much. If Vac is present then it must be leaking off further down the line.

6BUBBA9

bye iwe you mean the actuators at the hub right?

and as far as pulling a line to get it to go in 4wd which line would you pull?

Rossco

Just to clear up any confusion at my end:

Your 4x4 will not engage?

Your 4x4 will not disengage?

Here check this out

IWE's are the wheel actuators. (integrated Wheel End : I think)

I pulled the vac line at the IWE. Installed a vac gauge, built Vac up then rev the engine and hit the brakes etc. a drop in Vac is 90% probability it's a check. That's if you know the Rest of the components are good.

6BUBBA9

It will NOT engage

Rossco

Ah. The IWE's are spring applied, Vac release.

So you either have a bad IWE or Vacuum is being applied.

Fairly rare that the 4x4 will not engage at the hubs. Normally the other way round.

6BUBBA9

sorry for asking so many questions, but what would you do? lol

Rossco

At the moment? -10C, 10ft of snow everywhere.

IDE pull the vac lines off of the IWE's or, pull the lines at the tank / solenoid and run with the hubs locked in.

If you have a garage then.

Lift the front wheels. Start engine and spin the tires. In 2wd the drive shaft should not turn. Pull the vac lines off and repeat.

The only way the hubs should disengage is with Vac. If no vac and no release you have a mechanical problem at the hub.