I recently replaced my 4x4 actuator hubs, solenoid and check valve. A couple days after doing this after driving for 10 minutes or so I hear a grinding noise coming from the passage side wheel. If I switch to 4 wheel the noise will go away and I can switch back to two wheel drive after a few minutes and it will go another few minutes until the grinding comes back. Any ideas? TIA

 

make sure that you don't have a vacuum leak, the plastic tube that holds the vacuum on the IWEs. once the years pass the plastic gets brittle causing cracks and letting vacuum out, causing the IWEs to try to engage making that grinding noise.

 

Actuator gear. Just had the exact same problem. The metal gear part, not sure what it's called, is attached to a round piece of plastic, the plastic broke letting the metal gears touch. I found that out when I took it to a brake and tire shop, thought it was my wheel bearings. Owner of the shop said he thought it was the actuator gear. Told me to take it for a drive, when it started making noise, turn on the 4WD, if the sound goes away it's the actuator gear. I took it for a drive, everytime it made noise I turned on the 4WD and the sound went away. Took it back to his shop, he replaced the gear, I've driven it over 100 miles since then and the sound hasn't come back.

 

When you say the actuator gear are you talking the actuator hub assembly or is a different part? I did just replace both sides? Maybe I did something wrong. Was yours intermittent as well or did it constantly grind when you were in 2wd? Thanks

 

It did it when I hit about 30 to 35mph. Also when I hit a bump/pot hole and when I was turning. Sometimes I could get up to 45mph on a flat straight road and it wouldn't do it. So yes, it was intermittent.

This
Not sure that's the exact specific one for an F150, but that's what it looks like. The metal part in the middle had broken off from the plastic that it's attached to.

 

the actuator hubs/ IWEs are should have 2 little metal tubes coming out of it. those 2 metal tubes connect to 2 plastic tubes going all the way to the top of the engine and to the other front tire. if you have a crack in any part of that plastic tube your IWEs/ actuators are going to try to engage the 4wd causing that grinding noise. also double check your solenoid and check valve are good because when those 2 go bad they cause the same issue your experiencing. but since they are new its probably a leak in your system.

google (Weak Vacuum Line and grinding noise FIX) should take you to the raptor forum there's a good post about this issue. i would post the link but I think we cant post links to other forums.

the lines going from your IWEs to the top of the truck should look like this

 

what do you mean by "actuator gear"? thanks.

 

Inside the IWE, there's a part with teeth looking like a gear that engages into a female carrier. That's what he's talking about.

https://www.f150forum.com/f2/iwe-replacement-517411/

 

It is pretty much a synchronizer assembly. The gear spins at the same rate as the shaft, and when vacuum is applied, it pulls away, still spinning, becomes 2wd. When vacuum is removed, it springs back, locks in the axle, since it is spinning at the same speed as the shaft, it slips right in, and you can shift on the fly.

That is how it can engage at any speed. If there are any vacuum issues, it can apply partially, which is not good.
A mechanic told me to put a generous amount of red synthetic Mobil low temp grease in the assembly. When I did the ball joint that is exactly what I did.

 

Also if you have problems with this system, try adding an extra check valve. It is like $7. Also feel/wiggle the hoses while testing with a vac gauge. Check for any leaks or bleeddown.

Also see if the hub actuator holds vacuum for a a few minutes.

It it pretty simple otherwise.