Aeromech

Guys,
I hated to start a new thread but after reading through the sticky on T/S 4x4 I couldn't find an answer to my question which is....

Front end raised. Engine off. Spin left front wheel (either direction) and hear clicking or ratcheting sound. Drive axle not turning. Right front wheel spins with no sound and no axle turning.

Start engine. Spin left front wheel. Sound gone.

So I'm trying to understand the system and wondering if this is a problem for me or not. Thanks.

Aeromech

oops, 2006 F150 Lariat Screw 4x4 5.4 automatic

VTX1800N1

Your driver front IWE is likely rusted, not allowing it to fully engage. Remove and inspect the IWE and the hub gear interface.

Aeromech

Ar you saying that you think when I'm driving and try to engage 4wd that the left front IWE will not lock the hub? Sounds to me more like what's happening is that the vacuum bleeds down with the engine off allowing the IWE to try and lock because as soon as I get vacuum the clicking goes away. Or am I completely wrong?

lewissa81

You are almost completely right, but on the wrong track. The vacuum doesn't bleed down when the engine is shut off, it's completely released. The actuators lock in (or at least try to) everytime the engine is shut off. The idea is to keep the parts moving even so that they don't freeze up if you don't use the 4wd for a long time. It sounds like your iwe is either partially enganging, or the teeth to the actuator and/or hub are stripped out. You'll probably need to take it all apart to inspect it to know for sure.

VTX1800N1

It's supposed to lock when you turn the engine off.

techrep

iTrader: (1)

listen to VTX...pull apart your IWE’s inspect and repair..

Aeromech

The vacuum doesn't bleed down when the engine is shut off, it's completely released.

I did a lot of reading yesterday on how the system works but never read that the vacuum is released when the key is off. I did read about check valves and vacuum boxes which makes me believe the opposite. That the check valves and vacuum box hold vacuum and that the solenoid releases the vacuum only when 4WD is selected. I will yield to your experience though. I have no problem pulling it all apart like you suggest. The only thing is though that when I initially checked the clicking with the front end raised, the left wheel clicked and the shaft didn't turn. The right wheel didn't click and the shaft also didn't turn. I assume that with the engine running and selecting 4WD high that if the shafts don't lock I'd get a warning? Could my whole front end not be locking and I wouldn't even know it?

techrep

iTrader: (1)

You have a bad IWE... theres a seal in them.. if this seal is degraded it will leak your vacuum...or you may even have a bad line trying to provide vacuum. remember default mode when no vacuum is your hubs are engaged....vacuum will dis-engage the IWE’s ...if there’s not enough vacuum you will get a partial engagement (the clicking sound your hearing).

lewissa81

^^^ What techrep said. We know you have atleast one bad iwe actuator(it's clicking when the engine is off, it shouldn't do that). Now you need to determine why it went bad. Follow the entire procedure on checking the vacuum lines and their components. If you find something else is bad, fix it. Then replace the bad iwe actuator. Be prepared to replace the hub, but there's a chance it may be ok. Once the bad actuator (and possibly hub) and vacuum system are working correctly, test the other actuator to confirm if it is bad or not. Good luck!